PREFLIGHT WEATHER ANALYSIS MADE EASY

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2 PREFLIGHT WEATHER ANALYSIS MADE EASY ebook Series Version 1.3 Copyright 2012 Find-it Fast Books No part of this ebook, or in its entirety, may be reproduced or retransmitted by any electronic or mechanical means including information storage and retrieval systems for the purpose of sharing with others without the express written consent of the author. by Jerry Miller 406 Henry Drive Montoursville, PA The writer does the most who gives his reader the most knowledge, and takes from him the least time. -Sydney Smith ( )

3 TABLE OF CONTENTS Topic Page HOW TO USE THIS BOOK... 1 FIRST, GET THE BIG PICTURE (Pertinent to Your Route of Flight) Weather Depiction Chart... 2 Surface Analysis Chart... 3 Satellite Image Charts... 4 Short Range Surface Prog Charts... 5 Low level Significant Weather Charts... 6 High Level Significant Weather Chart... 7 Constant Pressure (Upper Level) Charts... 8 Convective Outlook Forecast... 9 Lifted Index / K Index Chart National & Regional Mosaic Radar Charts Radar Summary Chart WSR-88D Doppler Radar Discussion Modes of Operation Echo Intensities Echo Tops Base Reflectivity Composite Reflectivity Limitations Radar Weather Report (SD) AWW / WW Alert Msgs & Sev Weather Watches Convective Sigmets Thunderstorm Do s & Don ts Inadvertent Thunderstorm Penetration Airmets (WA) ZULU, TANGO, SIERRA Sigmets (WS) Center Weather Advisory (CWA) NOW, EXAMINE THE WEATHER FOR YOUR ROUTE OF FLIGHT IN DETAIL Use the FAA Standard Weather Briefing Format as Your Guide Synopsis Adverse Conditions: Icing Turbulence IFR Conditions Mountain Obscuration Thunderstorms Other Potential Hazards VFR Flight - Is It Advisable? Current Conditions: METARS... 35,36 Pilot Reports (UA), Urgent Pilot Reports (UUA)...37 Departure Forecast, TAF or Area Forecast if no TAF... 38,39 i

4 TABLE OF CONTENTS Topic Page EXAMINE THE WEATHER FOR YOUR ROUTE OF FLIGHT IN DETAIL (Con t) Enroute Forecast: Area Forecast (FA) and TAFs... 40,41 Destination Forecast, TAF or Area Forecast if no TAF... 42,43 Winds Aloft Forecast (FB) Notices To Airmen (NOTAMs)... 45,46 Temporary Flight Restrictions and Special Use Airspace Air Traffic Control (ATC) Delays SO, CAN YOU GO AS PLANNED? Filing Flight Plans, VFR and IFR AFSS Tips and Information, If You Wish to Call APPENDICES Self Briefing Master Pages for Copying... Appendix A National State Identifier Map & Decoder... Appendix B WA / WS / WST National Plotting Map & Decoder... Appendix C Weather Radar Site Locations Map & Decoder... Appendix D National TAF Location Maps & Decoder... Appendix E Clouds, Clues, and Effects on Flight... Appendix F ii

5 Look Here For Examples: In this block, you will find an example or a subject-related sketch of the weather product discussed on the current page. At times a translation or decoding of this example will follow in the big block below. Some pages are in two column format. These pages are a continuation of the current weather topic under discussion where additional space is needed for a more detailed explanation or examples of the weather product being reviewed. Begin Here On Each Page: In this block, you will find data relating to the issuance times of the weather product discussed on the current page. A brief description of some highlights about the weather product will also be presented. With the multitude of ways now available to access aviation weather on the Internet, you may already have your favorite. The weather products discussed here can be accessed by using the following url: How to Use This Book: This book is formatted in the sequence that a pilot weather briefer uses in conducting a pre-duty briefing to develop the Big Picture. You should do this, as well, to get an overview of the weather, with an eye for those weather features relevant to your proposed route of flight. Beginning on page 27, your journey focuses on the specifics of your flight, where you will examine the weather in the detailed manner a pilot weather briefer uses to deliver a standard weather briefing. This will ensure that every aspect of the weather is covered and fully understood by you prior to your flight. Perform every one of your briefings at the beginning of this book, working your way progressively through to the last page. Use those pages appropriate to the capabilities of your aircraft, and those pages pertinent to the complexity of the weather. By doing this each and every time, you will develop a consistent habit pattern in reviewing your weather so you will not overlook any critical information that might have an adverse impact on your flight. In addition to translations of the example weather product in the block above, this block includes some thoughts to consider in your decision making process. A description of the weather product featured on the current page is included, along with a discussion or more detailed information about the topic at hand. Every block on each page contains highlights about the weather subject under discussion. The blocks contain similar subject material on each page throughout the book. This consistent format will help you locate information quickly when you refer back to a topic you might want to refresh your memory about at a later time. You will occasionally notice some repetition of data throughout the book. The reason for this is that on those days when certain weather hazards may not occur, you will continue to have access to this important information on other pages where another set of weather hazards are pertinent to the safe conduct of your flight. A large collection of appendices will help you decode weather and Notam contractions and symbols, pinpoint locations of various weather hazards through a series of maps, and explore web sites that provide aviation weather information helpful to you. The web site urls listed in this book were verified as active at the time of publishing. This book is to be used for analyzing weather data in the continental United States only. Look for Tips, Highlights and Important Points Such as: HERE Always check the VALID TIME of every weather product you analyze to make sure it is pertinent to the time frame of your flight. You will find more tips, and important points listed here, as well. ACKNOWLEDGEMENTS: Many of the images depicted within this book were obtained from National Weather Service and FAA resources, to provide examples of weather products. These images are not subject to copyright protection. 1

6 U.S. Government Image Weather Depiction Chart The Weather Depiction Chart Transmits every 3 hours with valid times of: 0100Z, 0400Z, 0700Z, 1000Z, 1300Z, 1600Z, 1900Z, 2200Z Depicts areas of observed: IFR conditions: Shaded areas. Red on color charts. Ceiling less than 1,000 FT AGL and visibility less than 3 SM MVFR conditions: Unshaded solid lined areas. Blue on color charts. Ceiling of 1,000 FT AGL to 3,000FT AGL and visibility of 3 SM to 5 SM VFR conditions: Does not imply the sky is clear. No ceiling, or ceiling greater than 3,000 FT AGL and visibility greater than 5 SM Start With the BIG PICTURE The Weather Depiction Chart is a good starting point for analyzing the current weather by providing an overview of areas of low weather (IFR), marginal weather (MVFR), and good weather (VFR). Questions to ask yourself: In relation to my planned route flight at the valid time of the chart: If planning a VFR flight, is the current weather along my route favorable for safe VFR flight? (There s still much more to look at before making that complete determination!) If planning an IFR flight, in which direction must I fly to get to good weather if I experience equipment problems? How far away is the good weather from my planned route of flight? Do I have enough fuel to get there? Knowing where to find VFR weather, if flying under instrument flight rules, offers more alternatives. Remember Conditions depicted may not be accurate due to variations in terrain and areas of unobserved weather between reporting stations. Never rely on this Chart alone to make your preflight weather decision. Weather Depiction Chart Station Plot Example U.S. Government Image Questions to ask: What is the valid time of the Weather Depiction chart? Where is the good weather? Where is the bad weather? What is the extent of each type of weather? Why is the weather good or bad? The Surface Analysis Chart on the next page will help to determine the weather causes. TIPS on Station Plots: If sky cover is clear, few, or scattered, no ceiling will be plotted. No ceiling is plotted for total surface-based obscurations. Partial obscurations are not identified. If there is no cloud layer above, the sky symbol will be plotted as missing. If a cloud layer is above the partial obscuration, ceiling height is the cloud layer only. Compare with the METARs. 2

7 U.S. Government Image Surface Analysis Chart (SA) Transmitted every 3 hours with valid times of: 0000Z, 0300Z, 0600Z, 0900Z, 1200Z, 1500Z, 1800Z, 2100Z The primary purpose of the Surface Analysis Chart is to readily locate pressure systems and fronts. Surface Analysis Chart See Appendix H for Weather Symbols The Surface Analysis Chart depicts: Station models, the location of fronts, ridges, troughs, high & low pressure system centers, and lines of equal pressure (Isobars). What s Causing the Weather? In addition to a general overview of the Surface Analysis Chart, relative to your planned route of flight, ask yourself: Where are the frontal systems? The cold fronts, the warm fronts, the occluded fronts? Where are the pressure systems? The highs, the lows, the ridges, and the troughs? Highs typically indicate areas of good weather but not always! Lows are associated with bad weather, sometimes referred to as disturbances. Ridges are indicators of good weather, whereas troughs usually have troubled weather to the east of their position. How strong are the pressure system gradients? The closer the isobars, the stronger the gradient, and therefore the stronger the surface winds will be. Surface winds generally parallel the contours of the isobars, with a slight cross bar deflection toward lower pressure due to surface friction. Compare the graphics of this chart with the Area Forecast (FA) synopsis. Sometimes the text based synopsis of the Area Forecast will generally agree with the Surface Analysis Chart. But quite often you will find considerable disagreement. This doesn t necessarily mean one or the other weather product is wrong. They are simply stated differently. The meteorologists writing up the Area Forecast synopsis will describe synoptic features relating specifically to their area of responsibility. A synopsis is a description of the weather patterns affecting a large area. It can also be described as a brief summary of the location and movements of fronts, pressure systems, and circulation features. You should make up your own synopsis based upon what you see on the Surface Analysis Chart. This will help you to better understand what s causing the weather along your intended route of flight. TIPS: Low pressure circulates counter-clockwise. High pressure systems circulate clockwise. On the SA Chart, isobars are solid lines of constant or equal pressure usually spaced at 4 millibar (mb) intervals. Pressure patterns depicted by the isobars display the central pressure of Highs (H) and the central pressure of Lows (L). TIPS: Depicted tropical storms and hurricanes are low pressure systems with their names and central pressure noted. If you can t find a cause for low weather conditions when surface high pressure seems to dominate, it s likely to be a trough aloft or in other words, an upper level low. Taking a look at the upper air charts will confirm this. 3

8 U.S. Government Image GOES North America Color Enhanced Infrared Image GOES = Geostationary Operational Environmental Satellite Satellite Images Images Discussed Here (There are others) Visible Imagery: Looks like a black & white photo. Thick clouds appear brighter white than thin clouds. Land and water surface appear in shades of gray. Produced by reflected sunlight is only available during daylight cannot be seen after dark. Has a higher resolution than infrared imagery so smaller features can be distinguished better. Infrared Imagery: Senses energy as heat so it can provide imagery during the day AND at night. Cloud, water, and land mass appearances are much the same as visible imagery. Higher cloud tops are colder, so they appear a brighter white, which generally correlates to thunderstorms. A color enhanced IR image is depicted to the left. Make Some Quick Appraisals, But Be Careful! Satellite imagery is best left to the experts for accurate analysis, but it can offer some quick answers to where the cloud free areas are located. On those hot, muggy days of summer when thunderstorms are forecast, they are not being reported in the METARs, and there are no echoes on the Radar Summary Chart, a quick look at the Satellite images can reveal the building cumulus and towering cumulus clouds which are potential thunderstorms in their building stage. These are the likely locations where thunderstorms will soon begin to occur. These images are fascinating. They display some beautiful views of massive thunderstorms, cloud shield edges, and hurricanes. On foggy mornings, these images reveal the coverage of the fog or mist. Compare this imagery with the Weather Depiction Chart to see the extent of the fog. Widespread fog dissipates from the outward edges, inward. Satellite images display some very impressive views of thunderstorms. If you use zoom-in capability, 3-D cloud textures and thunderstorm anvils can be readily viewed very interesting to look at. For your use, Satellite images give you a general bird s eye view of the real weather happening down here. But, if you have not taken the National Weather Service Weather Radar Interpretation course, leave the true interpretation up to those trained in understanding all of the subtleties that make this imagery so complex to accurately analyze. TIP: With Visible Imagery: In the early morning and in the late evening, the shallow sun angle creates somewhat of a 3-D effect which makes clouds more pronounced, casting shadows on lower clouds. As the sun rises, during the midday hours, the shadows disappear. However, the clouds change to a brighter white as the sun reflects off the cloud tops more directly. TIPS: With the satellites positioned over the equator, they view the northern hemisphere at an angle which gives a view of the vertical development of clouds. Taller clouds cast shadows onto lower ones so visible imagery is a nice tool for pinpointing developing thunderstorms. In the winter, don t confuse snow cover on the ground with fog or cloud cover. 4

9 U.S. Government Image Short Range Surface Prog Charts Short Range Surface Prog Charts 12 hour chart: Issued at +/- 1720Z, valid at 0000Z 2310Z 0600Z 0530Z 1200Z 0935Z 1800Z 24 hour chart: Issued at +/- 1720Z, valid at 1200Z 2310Z 1800Z 0530Z 0000Z 0935Z 0600Z 36 hour chart: Issued at +/- 1720Z, valid at 0000Z 0530Z 1200Z 48 hour chart: Issued at +/- 1720Z, valid at 1200Z 0530Z 0000Z These charts give an overview of the progression of weather over the next 48 hours, with a snapshot of the weather at the valid times of the charts. What s Going to Happen Over the Next Couple of Days Relative to Your Flight? After examining the Weather Depiction and Surface Analysis Charts, keep that picture in your mind while cycling through the Surface Prog Charts, one after the other. To develop an appreciation for the expected future movement of the various weather causers and resulting areas of precipitation, make special note of the time flow of the sequential charts. Watch the movement patterns of the low pressure systems and associated fronts, indicating potential lower weather conditions. Note the areas of high pressure. Where are the areas of precipitation moving to? Into your planned route? What s the forecast coverage of the precipitation? Shaded areas indicate more than 50% coverage. Un-shaded areas indicate 30-50% coverage. What type of precipitation is expected? Liquid, freezing, or frozen? Thunderstorms? Note the bold dashed lines separating the different types of precipitation. Cycle through the Surface Analysis Chart, the Weather Depiction Chart, these charts, and the Low Level Significant Weather Charts (discussed next) as many times as it takes for you to comprehend the sequence of events to form your mental picture of the upcoming weather. The major concern with these charts is that what s depicted very seldom turns out to be what occurs at the forecast future time. Weather is simply too dynamic to accurately forecast over the long term. But it s better than nothing and, besides, sometimes they just happen to call it right! Whether you are planning a round-trip flight now, or a flight in a day or two, having a grasp of the weather trend is an important part of your decision making process. You may have good weather conditions favorable for your and the aircraft s capabilities for departure. But will the expected weather allow you to safely return later? If not, should you go on that trip at all if it appears that the weather will soon deteriorate? WAGS & SWAGS These charts work well for planning. But don t trust the charts to fulfill the depicted prognosis accurately. Think of the Prog Charts as giving you a general trend of future events. The 12 & 24 hour charts are a WAG - A wild guess. The 36 & 48 hour charts are a SWAG STRICTLY a wild guess. 5

10 U.S. Government Image Low Level Significant Weather (SIGWX) Charts 12 hour chart: Issued at +/- 1720Z, valid at 0000Z 2300Z 0600Z 0530Z 1200Z 0935Z 1800Z 24 hour chart: Issued at +/- 1720Z, valid at 1200Z 2300Z 1800Z 0530Z 0000Z 0935Z 0600Z Significant Weather Prog Chart These charts provide an overview of designated aviation hazards from the surface to 24,000 feet (FL240) over the next 24 hours. A snapshot of the expected weather is depicted at the valid times of the charts. What Aviation Hazards Can You Expect Over the Next 24 Hours? Now that you ve examined the weather makers and areas of precipitation expected over the next few days, examine the Low Level SIGWX charts for the aviation hazards potentially affecting your flight. Is the expected weather for your proposed route VFR? Marginal VFR? IFR? Or will it possibly be a mix of these three flying categories? Are areas of turbulence likely along your route? What intensities are expected? Moderate, severe, or extreme? Make note of the uppermost boundary and base of the turbulence. Is the turbulence aloft at the higher altitudes, or is it surface-based upward. A rule of thumb: The higher the upper limit of surface-based turbulence, the stronger the low altitude and surface winds. Though icing is not specifically forecast, it can be inferred by comparing the freezing levels of the SIGWX charts with the areas of precipitation of the Surface Prog Charts. As the general weather patterns cool in the fall, pay special attention to the dashed freezing level lines set at 4,000 foot intervals, denoting the freezing level aloft, above mean sea level. If your flight path travels between the 4,000 foot interval lines, interpolate the freezing level for your route. As the weather turns more frigid, look for a jagged line indicating that the freezing level is at the surface. A clearly defined legend is included on this chart which is very simple to understand. Take the time to study it so you can accurately interpret the symbology on these charts for the hazards that could affect your flight. Hazards Depicted on the SIGWX Charts: The flying categories: VFR Marginal VFR (MVFR) IFR Turbulence: Moderate Severe Extreme Freezing Levels: Surface, and aloft at 4,000 foot MSL intervals TIP: Comparing current weather with the previously forecast weather, and then comparing this trend with the future forecast charts can aid your decision making process. If the expected conditions were accurately forecast, this trend is likely to continue. The WAG and SWAG principle applies for these charts, as well 6

11 U.S. Government Image High Level Significant Weather (SIGWX) Chart Issued four times a day at: 1100Z, valid at 0000Z 1700Z 0600Z 2300Z 1200Z 0500Z 1800Z This chart provides an overview of designated aviation hazards above 24,000 feet (FL240). High Level Significant Weather Chart Is a one day forecast of significant weather from FL250 thru FL630 for en route flights. Offers a snapshot of the expected hazards depicted at the valid times of the charts. What Aviation Hazards Are Forecast From FL250 Through FL630? The High Level Significant Weather Chart is a one day forecast chart of en route aviation hazards typically used for international flight analysis by airline dispatchers. Charts are available for the continents around the world. Depicted above is the Americas chart, which may be a preferred chart for domestic flights by high performance aircraft pilots. Symbology Examples on the High Level Significant Weather Chart: Arrowhead indicates direction of jet. Jet Stream Axis FL (flight level) indicates altitude. Turbulence Bold green line Wind change lines & barbs = speeds. 360 Bold yellow 280 dashed lines FL320 Thunderstorms Cumulonimbus Tropical Storm FL340 OCNL EMBD CB 480 XXX Tropopause Heights H 530 Harvey 420 Hurricane Katrina 290 L Moderate turbulence from FL360 to FL280. If the lower digits are XXX, indicates FL240 and below. 1/8 to 4/8 coverage of embedded thunderstorms, tops FL480, bases FL240 and below. Lines of CBs with 5/8 coverage or greater. Depicted with long dashed white lines and V s. Tropical cyclones are depicted with the storm s name. CB clouds are shown with the storm. Widespread sandstorm or dust storm, top FL280, base FL240 and below. Tropopause heights are plotted in hundreds of feet MSL. Centers of highs & lows depicted by H & L. The dot at the trapeziod base is the volcano location. Volcano name & LAT/LONG is depicted. Severe Squall Lines V Sandstorms Dust Storms S V 280 XXX Volcanic Eruption Sites MT. ST. HELENS (LAT/LONG) Hazards Depicted on the SIGWX Charts: Jet streams above 80 knots. Moderate to severe turbulence Wind shear zones and mountain wave action. Cumulonimbus clouds and thunderstorms which imply moderate or greater icing and turbulence, plus possible hail. Squall lines. Tropical storms & hurricanes. Sandstorms and dust storms. Volcanic eruptions. TIP: Icing outside of thunderstorms is not forecast due to its rare occurrence above FL240. CB Coverages: ISOL = Less than 1/8 th OCNL = 1/8 th to 4/8 th FREQ = More than 4/8 th EMBDD = ISOL and OCNL CBs will not be depicted unless they are embedded in clouds, dust, or haze. 7

12 U.S. Government Image Constant Pressure Charts Issued twice daily. Charts are valid at 0000Z and 1200Z. Offer a snapshot of the observed weather depicted at the valid times of the charts. 500 MB Constant Pressure Chart FL180 or 18,000 Feet Above altitudes assume a standard atmosphere. The charts are quasi-horizontal contour maps. What Can the Upper Level Charts Tell Me? All upper level charts have a number of features in common, with a few distinctions: Solid black contours are lines of constant height referenced to MSL. The solid black contour lines map the height variations at 30 meter intervals of constant pressure surfaces in 3 digits, example: 150 = 1,500 meters. Contour patterns depict highs, lows, ridges, and troughs: An H depicts the center of a high, an L depicts the center of a low. Wind speed is directly proportional to the contour gradient -- the closer together the contour lines, the stronger the winds. Wind direction is parallel to the contour lines. Surface friction is absent except at higher terrain elevations for the 850 MB chart and near the tallest mountain peaks for the 700 MB chart. Red dashed lines, called Isotherms, are lines of constant temperature, depicted at five degree Celsius intervals. The zero degree isotherm depicts the freezing level. Isotherms are labeled with two digits preceded with a + sign (positive temperatures), or a sign (negative temperatures). Negative temperatures are above the freezing level. The constant pressure charts can be used to: Identify mountain obscuration on the 850 MB and the 700 MB charts (remember the blacked-in station plots indicate saturated air, meaning the likelihood of clouds.). Identify areas of icing on all charts blacked-in station plots and negative temperatures. Identify adverse headwinds or favorable tailwinds on all charts. Identify adverse turbulence located at areas of close-together, sharply defined contours. The 300 MB, 250 MB, and 200 MB charts can be used to identify Clear-Air-Turbulence associated with the jet streams, areas of extremely strong winds, and the jet stream axis. Use caution when analyzing the Constant Pressure charts. They represent valid times of only twice a day. Significant atmospheric changes can occur between chart times. Meteorologists use these charts to develop their forecasts. If you find these charts useful, keep in mind that they are valid only twice a day at 0000Z and 1200Z. TIPS: Darkened station circle plots indicate the station is either saturated or nearly saturated. This means there most likely are clouds at these altitudes. Station plots may be circles, stars, or squares: Circles are radiosonde data. Stars are satellite data. Squares are aircraft data. Jet Streams: A jet stream is comprised of winds equal to or exceeding 50 knots concentrated within a narrow stream in the atmosphere. The axis of maximum wind speed in a jet stream is called the jet stream axis. On the 300 MB, 250 MB, and 200 MB charts, a jet stream is depicted whenever the wind speed equals or exceeds 70 knots. The simplified discussion on this page can be supplemented in depth by reviewing the FAA Circular AC-0045F and the Aviation Weather AC-006A. 8

13 U.S. Government Image Convective Outlook Chart Day 1 Chart: Issued 5 times daily. Day 1 issuances are valid from the issuance time until 1200Z on the following day. Day 1 Chart: Issued at 0600Z, valid Z 1300Z Z 1630Z Z 2000Z Z 0100Z Z Day 2 Chart: Issued at 0730Z (Daylight Svgs Time) 0830Z (Standard Time) Day 2 Chart: Valid on 2 nd day from 1200Z Z Convective Outlook Chart Day 3 Chart: Issued at 1100Z, Day 3 Chart: Valid on 3 rd day from 1200Z Z Where Are Severe Thunderstorms Forecast Today, Tomorrow, and the Day After? Questions to ask yourself: Where are the areas of coverage affecting my flight? What is the risk of severe thunderstorms occurring? Where are the areas of general (non-severe) thunderstorms? The levels of RISK are defined as: SLGT = Slight risk Implies well-organized severe thunderstorms are expected, but in small numbers and/or low coverage. MDT = Moderate risk Implies a higher concentration of severe thunderstorms than the SLGT designation, and in most situations, a greater magnitude of severe weather than the SLGT designation. HIGH = High risk Almost always means a major severe weather outbreak is expected, with great coverage or severe weather and a strong likelihood of extreme severe events, such as violent tornadoes or unusually intense damaging winds. SEE TEXT Is used for areas where thunderstorms may approach or slightly exceed severe criteria. AC outlooks may be amended for errors or when current forecasts do not or will not reflect the ongoing future thunderstorm development. TIP: Think of the Day 1 chart as TODAY. Days 2 & 3 are good charts to use for advance planning at a glance to avoid expected thunderstorm development. A Severe Thunderstorm is defined as having: Wind Gusts 50 KT or greater or Hail ¾ in size or greater or the occurrence of a Tornado. General Thunderstorms: These are common everyday thunderstorms with heavy rain, lightning, and small hail (less than ¾ inch in diameter). Areas of general (non-severe) thunderstorms are outlined on the Convective Outlook Chart but they are not labeled. Severe thunderstorms are not likely in these areas, but some are possible. 9

14 U.S. Government Image Lifted Index Chart Issued twice daily with valid times of 00Z and 12Z. The 00Z chart updates at approximately 0330Z. The 12Z chart updates at approximately 1530Z. Offers a snapshot of stability and moisture indices depicted at the valid times of the charts. Simplified Explanation: Lifted Index (L I) measures atmospheric stability. The lower the number, the more unstable the air The K Index (K I) measures thunderstorm potential. The higher the number, the greater the potential for airmass thunderstorms. Lifted Index Chart Example: L 4 = = Severe Thunderstorms K 25 What is the Atmospheric Moisture & Stability? Use caution when analyzing the lifted values (L I) and the K Index (K I) values of this chart. It represents valid times of only twice a day. Significant atmospheric changes can occur between chart times. L I values are typically lowest or least stable during the afternoon hours due to surface heating. TIPS: Missing values of the K plot are denoted with the letter M. The K Index is a measure of thunderstorm potential based on vertical temperature lapse rate, moisture content and vertical extent of the moist layer. If the K Index value is 40 or higher, the probability of severe thunderstorms is near 100 percent. The L I and K I indices of atmospheric stability and moisture content interrelate to give an idea of the potential for thunderstorms. The below charts depict general probabilities. Many variables, such as synoptic picture, season, and location affect these likelihoods. Unstable and moist air is the most favorable atmospheric condition for thunderstorms. LIFTED INDEX 0 to -2-3 to -5-6 or Less K INDEX West of the Rockies CHANCE OF SEVERE THUNDERSTORMS Weak Moderate Strong K INDEX East of the Rockies Coverage of General Thunderstorms Lifting mechanisms such as mountains and cold fronts increase the severity of storms. Air Mass Effects: Moist and Unstable Air: High Thunderstorm Potential. Moist and Stable Air: Low Stratus and Precipitation. Take a look at Mississippi and Alabama, on the Lifted Index Chart. L I values are -4, indicating very unstable air, giving a moderate chance of severe thunderstorms at 0000Z. The K I values of 32 to 39 indicate a very moist air mass, indicating a likely coverage of scattered to numerous thunderstorms at 0000Z. Meteorologists use this chart to develop their forecasts. If you are one of those who find this chart useful, keep in mind that it is valid only twice a day at 0000Z and 1200Z. The simplified discussion on this page can be supplemented in depth by reviewing the FAA Circular AC-0045F and the Aviation Weather AC-006A. Dry and Unstable Air: Few or No Clouds, but with Convective Thermals. Dry and Stable Air: Most Favorable for excellent VFR flying weather. 10

15 U.S. Government Image National Weather Service National and Regional Mosaic Radar Chart Products: Data displayed is less than 15 minutes old. Most recent single site radars are depicted. Precipitation location and movement within 124 NM of individual radar sites depicted. National Mosaic Radar Chart (10 Regional Mosaics are also available) The National Mosaic is composed of this network of 158 Doppler radar sites located throughout the United States. These sites will be discussed in more detail during a detailed look at your enroute weather. Where is the Precipitation in Relation to Weather Depiction and Surface Analysis and, Especially, to Your Route of Flight? What is the precipitation intensity (light, moderate, heavy, etc.)? Loop the radar image to get an idea of direction and speed (rate) of movement? With the multitude of commercial and government weather products available, national radar summary depictions will vary in content. Some providers overlay additional enhancements, explained below: TOPS Depicted in thousands of feet, example: 300 = 30,000 feet. HAIL The probability for hail exists within the depicted thunderstorm. MESO There is the detection of a 3-dimensional rotating section of a thunderstorm. This is an indicator of extremely severe weather. TVS This indicates a Tornadic Vortex Signature. This means there is a potential tornado at this location. HOOK Hook echo. This is another indicator of potential tornadoes. Short Arrows with Numbers - The arrows indicate direction of movement of the precipitation echoes. The numbers indicate the speed of movement in nautical miles per hour. Weather Watch Boxes These boxes or polygons indicate severe thunderstorms and/or tornadoes are likely, or occurring. National and Regional NWS Radar Mosaics: Pacific Northwest Pacific Southwest Northern Rockies Southern Rockies Southern Plains Great Lakes Upper Mississippi Valley Southern Mississippi Valley Northeast Southeast Low Resolution National High Resolution National TIP: The Storm Prediction Center issues textual advisories which give highly detailed information about thunderstorm or tornadic activity. These advisories are encoded as a WW, which is a Weather Watch, or as an AWW, the abbreviation for an Severe Weather Watch Alert. Detailed information concerning Weather Watch Boxes depicted on the National Radar charts is available for study to give you a more complete explanation of the convective activity highlighted on the chart (Covered on page 18). 11

16 U.S. Government Image U.S. Government Image Radar Summary Chart A NWS Fax Product Issued Hourly Depicts a computer generated mosaic of precipitation: Type, Intensity, Coverage, Movement, Echoes, & Maximum Tops Radar Summary Chart Radar Summary Chart Precipitation Intensities One More Look From a Different Perspective Even though it is issued on an hourly basis, let s not forget the tried and true Radar Summary Chart from days gone by to get a better picture of the precipitation and thunderstorm threat influencing your proposed flight. Viewing the Radar Summary chart in addition to the more timely Doppler radar will answer many questions in interpreting the echoes you ve taken a look at previously on the WSR-88D Doppler Radar Mosaic Charts. SEVERE THUNDERSTORM AND TORNADO WATCHES are also plotted on the Radar Summary Chart if they are in effect when the chart is valid. They are indicated by a box or a polygon with the watch number for identification. More than one watch can be in effect at the same time. NE = No Echoes The absence of echoes does not mean that there is clear or cloud free weather in the areas depicted. The Radar Summary displays drops of ice particles or precipitation only. It does NOT display clouds and fog. Weather Watch Boxes These boxes indicate severe thunderstorms and/or tornadoes are likely or occurring. The Storm Prediction Center issues textual advisories, giving highly detailed information about the convective or tornadic activity. These are encoded as a WW, which is a Severe Weather Watch Bulletin or an AWW, an Alert Message. Don t confuse NE with NA NE = No Echoes (present) NA = Not Available (missing radar report) 12

17 U.S. Government Image Analyzing Thunderstorms with the WSR-88D Radar Network The WSR-88D Doppler Radar Network is the best method for evaluating the thunderstorm threat in almost real-time. With 5 to 10 minute radar image updates, depending on the mode of operation, a flight avoidance plan of alternate routing, departure time change, or cancellation of your flight can be readily determined. National Weather Service Base Reflectivity Image The following pages offer an overview of the WSR-88D Doppler radar network. Where Are the Thunderstorms Relative to Your Proposed Route of Flight? Questions to ask yourself in more detail: Are the depicted echoes: cells, areas, lines, or bands of precipitation? In what direction is the precipitation moving? At what rate of movement? What is the intensity of the precipitation (moderate, heavy, extreme, etc.)? How high are the tops of the precipitation? Is the precipitation stratiform or convective? If the precipitation is convective, are the thunderstorms organized in lines of frontal activity, or disorganized air mass thunderstorms? If air mass type thunderstorms are depicted, are conditions ripe for greater convective activity? That is, higher atmospheric moisture and instability (hot and humid)? It s impossible to forecast exactly when and where popup air mass thunderstorms occur. A forecast for isolated thunderstorms can occasionally become clusters of storms. When animating (looping) the radar images, watch for an increase of cells with each update of the image. This thunderstorm development is usually quite rapid. In relation to your planned route of flight: Will the precipitation move onto your route? Can you plan a diversion in time, distance, or course to avoid the storms? If you plan a time diversion, will you wait awhile, depart sooner, or cancel? Very Important TIP: When viewing TOPS radar imagery products, do not to confuse the TOPS color-coded legend with reflectivity (Echo Intensity) colorcoded Legends! Make note of the legend titles. Also, the Reflectivity legend depicts DBZ, whereas Tops depicts KFT (thousands of feet). General Echo Intensity Color Codes and Effects Blue through Light Green Light precipitation Little or no turbulence Possible reduced visibility Dark Green through Yellow Moderate precipitation Moderate turbulence Possible low visibility Orange through Purple Heavy to extreme precip Severe icing & turbulence Thunderstorms Severe aircraft damage 13

18 WSR-88D Radar WSR-88D Doppler Radar Modes of Operation: WSR-88D Doppler radar displays precipitation and non-precipitation targets through a variety of products (web site: WSR-88D Doppler radar (Weather Surveillance Radar, 1988, Doppler) is also called NEXRAD (Next-Generation Radar). It is a network of 158 high-resolution Doppler radar sites operated by the National Weather Service. WSR-88D Doppler radar operates in two modes: Clear Air Mode and Precipitation Mode. Clear Air Mode is the most sensitive, with a slower antenna rotation which allows more time to sample the atmosphere. With this increased sensitivity, smaller objects can be detected, such as dust and particulate matter. Clear Air Mode updates every 10 minutes. Do not confuse Clear Air Mode as meaning there is no precipitation occurring. True, this mode typically is used when precipitation is not occurring. However, when greater radar sensitivity is needed to receive the return signals of light stratiform precipitation echoes (such as light snow), Clear Air Mode is used due to its higher sensitivity. Precipitation Mode will also return cloud signatures in the very low reflectivity ranges (discussed next). Precipitation Mode is employed when precipitation is present, which provides stronger return signals. With an increased antenna rotation speed, images update at a faster 4 to 6 minute rate. Non-precipitation echoes can still be detected in this operating mode, as well (discussed later). Always be sure to read the legend of whichever radar product you are using, so that you do not misinterpret the echo intensity color coding. WSR-88D Doppler Radar Echo Intensities Doppler radar displays both precipitation and nonprecipitation echoes by echo intensity. Echo intensity is also referred to as reflectivity. Precipitation intensity is measured in dbz (decibels of Z) and is color coded on a vertical bar scale. The dzb color coded bar scales for precipitation intensity are identical for both the Clear Air Mode and the Precipitation Mode. However the dzb scales are NOT THE SAME! Be sure to check the radar imagery for mode of operation when examining the precipitation echoes. The Clear Air Mode scale ranges from -28 to +28 dbz. The Precipitation Mode scale ranges from 5 dbz to 75 dbz. Remember The color on each scale is the same in both operational modes but the dbz values are significantly different. The bottom of the vertical color coded bar scales is denoted with ND, indicating no data measured. The higher the intensity of precipitation, the higher the reflectivity, and the higher the dbz value, and the higher the rainfall rate. Light precipitation, for instance, ranges in the dbz values of dbz. Hail is a good reflector of energy, returning very high dbz values, likely on the order of 50-75dBZ. When dbz values are below 15dBZ, the echo area depicted may be cloud cover or very light precip. Reviewing the METARs located below such echo areas quite often indicates no precipitation reported on the surface. 14

19 WSR-88D Radar WSR-88D Doppler Radar Echo Tops When examining the Echo Tops radar imagery, don t confuse the color coded vertical bar graph for precipitation echo intensities. This bar graph represents maximum HEIGHT of tops of PRECIPITATION (not clouds) denoted in thousands of feet (Example: 30 = 30,000 feet). The radar will not report echo tops below 5,000 feet or above 70,000 feet. Only the tops with a reflectivity of 18.5 dbz or higher will be reported. It s important to note, the radar is not able to see tops of thunderstorms close to the radar site. For extremely tall thunderstorms close to the radar site, the maximum tilt angle of 19.5 degrees of the radar antenna is not high enough for the radar beam to reach the top of the storm. An alternative to determine tops in the vicinity of the radar site is to view an adjacent radar site or examine the Regional or National radar mosaic. Areas of strong updrafts can be identified by using the echo tops presentation, pinpointing locations of high tops. Conversely, a sudden decrease in echo tops indicates the onset of a downburst, with strong downdrafts rushing to the ground (thunderstorms!). The Echo Tops product is presented in somewhat of a blocky appearance with series of small squares due to the image s lower picture resolution. Clarity of the image is not as important as is the color-coding of the imagery in determining the maximum precipitation tops for a given location, which is the primary purpose of this product. Again, as always, be sure to look at the legend of this product so that you do not misinterpret the imagery as echo intensity. It s TOPS you are examining on this image. WSR-88D Doppler Radar Base Reflectivity Base Reflectivity is used to determine the location, intensity and, when looping or animating the radar, the general movement of precipitation. At an antenna tilt angle of 0.5 degree above the horizon, precipitation beyond the maximum range of 124 NM will not be displayed even though it may be occurring. Often times this will result in a precipitation image ending abruptly in a circular, or arc-like pattern. A long range view of 248 NM is also available to view precipitation beyond the shorter 124 NM range. Other options for viewing precipitation beyond either the short or long ranges of coverage are to look at adjacent radar sites or to view the Regional or National mosaics. To determine if the viewed precipitation is either stratiform or convective, look for the following characteristics: Stratiform Characteristics: Light to moderate Intensities in the 39dBZ range or less (occasional intensities can be stronger). Widespread, slow changing echo patterns are apparent when animating (looping) the radar image. Hazards include low ceilings, reduced visibilities, and widespread icing above the freezing level. Convective Characteristics: Echoes tend to form as lines, clusters, or cells. Strong intensities that can vary from moderate to extreme (with occasional light intensities). Echo patterns change rapidly when animating or looping radar image. Hazards include strong and gusty surface winds, low level wind shear, turbulence, icing above the freezing level, lightning, hail, tornadoes microbursts, and localized IFR conditions with heavy precipitation. 15

20 WSR-88D Radar WSR-88D Doppler Radar Composite Reflectivity Composite Reflectivity is used to determine the vertical structure of precipitation. This is done by comparing the Base Reflectivity image with the Composite Reflectivity image for the same radar site at the same time. Base Reflectivity, in its 0.5 degree antenna tilt, is seeing the precipitation closer to the ground. The Composite Reflectivity image is scanning the precipitation at a number of higher altitudes, using a number of antenna sweeps at increasingly higher angles of antenna tilt. In essence, the radar is looking at columns of the atmosphere, giving information on structure and intensity trends of the precipitation within. If, for example, the Composite Reflectivity scan is displaying higher precipitation intensities and more echoes than the Base Reflectivity scan at the same location at the same time, then it can be concluded there is vertical development at that location. This is an indicator that rain showers of varying intensities, or thunderstorms are either developing or occurring. Base Reflectivity does offer an easy and straight forward ability to determine the location and movement of precipitation echoes. Better yet, Composite Reflectivity adds the more important ability of offering a three-dimensional view of precipitation to determine the presence of rain or thunderstorms (convective activity). As with the Base Reflectivity product, Composite Reflectivity offers a more distant 248 NM range, as well. However, a blocky appearance is evident with the 248 NM Composite Reflectivity product because it has one-fourth the resolution of the Base Reflectivity presentation. WSR-88D Doppler Radar Limitations Limitations of Base and Composite Reflectivity include: Ground Clutter Anomalous Propagation (AP) Radar Beam Overshooting Beam Blockage Angels Ghosts Ground Clutter is radar echo returns close to the radar site caused by buildings, trees, or terrain. WSR-88D radar removes most ground clutter to reduce interference in echo interpretation. Anomalous Propagation (AP) is a pattern of ground echoes occurring anywhere within the radar sweep caused by the radar beam bending down (superrefraction). AP generally appears speckled or blotchy with highly reflective echoes. AP can misinterpreted as thunderstorms. A quick check of other weather resources (METARS, Radar Weather Reports (SDs), etc.) will confirm if AP is occurring. Radar Beam Overshooting happens when precipitation is occurring far away from the radar site, and the radar beam extends above the tops of the precipitation, therefore it is not reporting any echoes. Viewing the adjacent radar sites or the Regional or National mosaic displays these unobserved echoes. Beam Blockage appears as a pie-shaped area or areas void of echoes caused by the obstruction of terrain. This is especially predominate in the more mountainous areas. Angels are generally caused by large groups of birds, bats, or insects. Angels typically appear as donut shaped echoes with a low reflectivity value. Ghosts are diffused echoes occurring in clear air caused by groups of pin-point targets, such as insects. Ghosts are also caused by the bending up of the radar beam in clear air, commonly at sunset. 16

21 IND 2045 LN 8TRW++ 86/40 164/60 30W MTS /65 C2135 AUTO ^M01 N02 0N3 Typical Radar Weather Report (SD/ROB) (Translated Below) Above SD Data Decoded: IND = Radar Site three letter location identifier = Time of the observation in four digit Universal Time Coordinated (UTC). LN = Configuration - In this example it is a Line. A Line is a convective echo meeting the following criteria: Contains heavy or greater intensity precipitation. Is at least 30 miles long. Length is at least four times greater than width. Contains at least 25 percent coverage. Other Configurations are: CELL A single, isolated convective echo. AREA A group of echoes of similar type, not classified as a line. 8 = Coverage Coverage of precipitation is coded in single digits representing tenths of coverage. TRW = Precipitation Type Determined by computer model. Reportable types of precipitation are: R = Rain RW = Rain Shower S = Snow SW = Snow Shower T = Thunderstorm ++ = Precipitation Intensity The reported intensities are: 86/40 164/60 30W = Location In this example, a Line (LN) A LINE is coded with two end points, and a width going two opposite directions perpendicular from the end points, which creates a rectangle. The end points are defined by an azimuth and a range, much like the fix, radial, DME (FRD) of a NAVAID point in space, except in this case the fix is the radar site. So, here, we have point 1 at 86 degrees and 40 NM, and point 2 at 164 degrees and 60 NM, creating a centerline. (go to next column ) Analyzing Thunderstorms with the Radar Weather Report (SD / ROB) An unscheduled computer generated textual report providing information about precipitation observed by weather radar. Typically is updated near the top of each hour, but data can be up to 80 minutes old. The SD report is useful if you do not have access to graphical radar imagery. From these two end points a perpendicular line is then extended, in this case, 30 NM, in BOTH directions to create a narrow rectangle. The line of thunderstorms is contained with this rectangle. An AREA is also defined in the same manner which will create a wider rectangle. A CELL is coded as a single point with the letter D. The number attached to the D is the diameter in NM. MTS /65 = Denotes the altitude in thousands of feet (480 = 480,000 FT), and then the location of the highest precipitation (not cloud) echo, in this example, 159 degrees at 65 NM from the radar site. All tops are estimates assumed in a standard atmosphere. MT indicates only radar data was used to estimate precipitation tops. MTS indicates both radar data and satellite data were used to estimate precipitation tops. C2135 = Cells moving FROM 210 degrees at 35 knots. Cell movement the average motion of cells within a configuration (direction in tens of degrees and speed measured in knots). Cell movement is referenced to TRUE north. Movement of AREAs and LINEs is not coded. AUTO = Report derived from automated weather radar. Other Remarks include: PPIOM Radar out for maintenance. PPINA Radar not available. PPINE Equipment normal and operating, but no echoes observed. ^M01 N02 0N3 = Digital section coding used to create the automated Radar Summary Chart. 17

22 1 SPC AWW WW 526 SEVERE TSTM IA IL Z Z 3 AXIS.. 45 STATUTE MILES EITHER SIDE OF A LINE WNW CID/CEDAR RAPIDS IA/ - 15E MLI/MOLINE IL / 5.. AVIATION COORDS.. 40NM EITHER SIDE /39NW IOW 33 WNW BDF / 6 HAIL SURFACE AND ALOFT INCHES. WIND GUSTS.. 70 KNOTS. MAX TOPS TO 500. MEAN STORM MOTION VECTOR Example Severe Weather Watch Alert Message (AWW) URGENT IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 526 NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF EASTERN IOWA NORTHWEST ILLINOIS EFFECTIVE THIS TUESDAY MORNING FROM 440 AM UNTIL 800 AM CDT. HAIL TO 1.5 INCHES IN DIAMETER... THUNDERSTORM WIND GUSTS TO 80 MPH... AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 45 STATUTE MILES EITHER SIDE OF A LINE FROM 25 MILES WEST NORTHWEST OF CEDAR RAPIDS IOWA TO 15 MILES EAST OF MOLINE ILLINOIS. FOR A (more) Example Severe Weather Watch Bulletin (WW) Severe Weather Watches (WW) and Alert Messages (AWW) WW boxes define areas of possible severe thunderstorms or of tornado activity: Are unscheduled and issued as required. Are valid from the time of issuance until the time of expiration or cancellation. Valid times are in UTC. An AWW is issued before the WW as a preliminary notification to flight service and other weather specialists. The AWW offers a quick overview of the affected areas. Are There Any Severe Weather Watches? Severe thunderstorm and tornado watches can be perplexing. Sometimes watches are issued when cloud free blue summer skies predominate. However, conditions are favorable for a significant risk of convective development. That is, high atmospheric moisture content and instability. Generally, the watches are quite justified and severe weather does occur. The uppermost AWW example, above, is decoded line-by-line as follows: 1. SPC = Issuing Office, the Storm Prediction Center, Norman, OK. AWW = Product/Message Type, Severe Weather Watch Alert Message = Issuance date/time, 17 th day at 0934Z. Watches usually last for 5 to 8 hours. 2. WW 526 = Watch number, the 526 th WW issued for the current year. SEVERE THUNDERSTORM = Watch Type. IA IL = States affected Z Z = Valid date/time period, 17 th day from 0940Z til 17 th day 1300Z. 3. AXIS.. 45 STATUTE MILES EITHER SIDE OF = The Watch Axis creates a BOX WNW CID/CEDAR RAPIDS IA? 15E The anchor points to complete the BOX. 5. AVIATION COORDINATES.. 40 NM EITHER SIDE /39NW IOW 33 WNW BDF These aviation coordinates are in nautical miles and are in reference to VORs. 6. HAIL SURFACE AND ALOFT Type, intensity, maximum tops, etc. dialog. Soon after the AWW is issued, the actual watch bulletin (WW) follows. The Severe Weather Watch Bulletin includes the following information: 1. Type of severe weather watch watch area valid time period type of severe weather possible watch axis meaning of a watch a statement that persons should be on the lookout for severe weather. 2. Other watch information, such as references to previous watches. 3. Phenomena, intensities, hail size, wind speed in knots, maximum thunderstorm (CB) tops, and estimated cell movement (mean wind vector). 4. Cause of the severe weather. 5. Information on updating convective outlooks (AC). A Severe Thunderstorm is defined as having wind gusts of 50 KT (58 mph) or greater or hail ¾ in size or greater. TIP: More than one WW can be issued during overlapping periods, creating confusion in sorting them out. Look at the portions of states listed to help you understand more easily the areas affected, and to see if they have an impact on your route of flight. When severe thunderstorms or tornadoes have developed within the WW Watch box issued by the SPC, local Warnings will be issued for the now observed thunderstorms or tornadoes by the local weather forecast office. The Watch remains in effect. WW status report messages may be issued referring to valid watch boxes. These messages will often cancel a portion of the original box, if the weather threat diminishes. 18

23 Western Central Eastern Convective Sigmet Regions 1 MKCC WST CONVECTIVE SIGMET 39C 3 VALID UNTIL 1355Z 4 TX OK KS MO LA NM 5 FROM 40S GLD-30E SGF-LIT-30SE SAT-20N ROW-40S GLD 6 AREA SEV TS MOV FROM 30025KT. TOPS ABV FL450. HAIL TO 1.5 IN... WIND GUSTS TO 60KT POSS. END WST 39C Plotted WST Convective Sigmet (WST) Bulletins Issued at 55 minutes past every hour for each WST Region (East, Central, and West) An individual WST is issued for each event. Each WST is identified by a letter/number. Each continuing WST event is updated and assigned a new letter/number combination. Valid for up to 2 hours an updated WST supercedes and cancels the earlier WST. If convective conditions do not meet WST criteria a negative message will be issued: CONVECTIVE SIGMET NONE Example Convective Sigmet (WST) Message Are There Any Convective Sigmets (WST)? The WST message example, above, is decoded line-by-line as follows: 1. MKC = Issuance office, NOAA s Aviation Weather Center, Kansas City, MO. WST = Product/Message Type, Convective Sigmet = Issuance date/time, twelfth day of the current month at 1155Z. 2. Convective Sigmet 39C = Message Type issuance number (39), followed by the letters W, C, or E (in this example C, indicating the Central Region - see top-left chart). 3. VALID UNTIL 1355Z = Valid time is four digits, the first two are the hour (13Z) in UTC and the last two are minutes past the hour (:55). 4. TX OK KS MO LA NM = Affected areas, state abbreviations for Texas, Oklahoma, Kansas, Missouri, Louisiana, and New Mexico. This does not indicate that an entire state is affected. Notice how small a portion of the northwest corner of Louisiana is included in the graphic map. This line helps you to quickly develop a mental picture of the affected area if only the WST text message is available with no associated map. 5. FROM 40S GLD-30E SGF-LIT-30SE SAT-20N ROW-40S GLD = Location of the phenomena somewhere within the described area not within the entire area. 6. AREA SEV TS MOV FROM 30025KT. TOPS ABV FL450. HAIL TO 1.5 IN... WIND GUSTS TO 60KT POSS. = This is the meat of the WST message, describing the existing or forecast convective conditions using standard contractions. A list of typical WST contractions are in the box to the right. A Convective Sigmet contains information about significant convective activity, potentially hazardous to all aircraft. A WST is issued when any of the below conditions exist or are forecast: Severe Thunderstorms Surface winds equal to or greater than 50 knots, hail equal to or greater than ¾ inches in diameter, tornadoes. Embedded thunderstorms hidden by haze, stratus clouds, or precipitation. Line of thunderstorms 40% or more coverage of a line 60 miles or longer. Active area of thunderstorms affecting at least 3,000 square miles, or very heavy or greater intensity of rain affecting 40% or more of the area. Coverages Defined: ISOL = Isolated - Single cells No percentage of coverage given for the area affected. WDLY SCT = Widely Scattered Less than 25% coverage of the affected area. SCT = Scattered or AREA = Area Indicates 25% to 54% coverage. NMRS = Numerous - or WDSPRD = Widespread Indicate 55% or more coverage of the affected area. ABV = Above CELL = Cell DMNSG = Diminishing DVLPG = Developing INTSFYG = Intensifying KT = Knots LINE = Line LTL = Little MOV = Moving NM = Nautical Miles POSS = Possible PSBL = Possible RPTD = Reported SEV = Severe TOPS = Precipitation Tops TS = Thunderstorm(s) 19

24 Convective Sigmet (WST) Bulletins Thunderstorm Do s & Don ts Since you will soon be departing on your flight, this is a good time to review the thunderstorm flying cautions listed in the FAA Aeronautical Information Publication: Above all, remember this: never regard any thunderstorm lightly even when radar observers report the echoes are of light intensity. Don t land or takeoff in the face of an approaching thunderstorm. A sudden gust front of low level turbulence could cause loss of control. Don t attempt to fly under a thunderstorm even if you can see through to the other side. Turbulence and wind shear under the storm could be disastrous. Don t fly without airborne radar into a cloud mass containing scattered embedded thunderstorms. Scattered thunderstorms not embedded usually can be visually circumnavigated. Don t trust the visual appearance to be a reliable indicator of the turbulence inside a thunderstorm. Do avoid by at least 20 miles any thunderstorm identified as severe or giving an intense radar echo. This is especially true under the anvil of a large cumulonimbus. Do clear the top of known or suspected severe thunderstorms by at least 1,000 feet altitude for each 10 knots of wind speed at the cloud top. This should exceed the altitude capability of most aircraft. Do circumnavigate the entire area if the area has 6/10 thunderstorm coverage. Do remember that vivid and frequent lightning indicates the probability of a strong thunderstorm. Do regard as extremely hazardous any thunderstorm with tops 35,000 feet or higher whether the top is visually sighted or determined by radar. Also Remember: Any Convective Sigmet implies IFR conditions, severe or greater turbulence, severe icing, and low-level wind shear. In addition, all thunderstorms contain turbulence, hail, rain, snow, lightning, sustained updrafts and downdrafts, and icing conditions. Inadvertent Thunderstorm Penetration: If you cannot avoid penetrating a thunderstorm, below are some Do s before entering the storm: Tighten your safety belt, put on your shoulder harness if you have one and secure all loose objects. Plan and hold your course to take you through the storm in a minimum time. To avoid the most critical icing, establish a penetration altitude below the freezing level or above the level of minus 15 degrees Celsius. Verify that pitot heat is on and turn on carburetor heat or jet engine anti-ice. Icing can be rapid at any altitude and cause almost instantaneous power failure and/or loss of airspeed indication. Establish power settings for the turbulence penetration airspeed recommended in your aircraft manual. Turn up cockpit lights to highest intensity to lessen temporary blindness from lightning. If using automatic pilot, disengage altitude hold mode and speed hold mode. The automatic altitude and speed controls will increase maneuvers of the aircraft thus increasing structural stress. If using airborne radar, tilt the antenna up and down occasionally. This will permit you to detect other thunderstorm activity at altitudes other than the one being flown. Following are some Do s and Don ts during the thunderstorm penetration: Do keep your eyes on your instruments. Looking outside the cockpit can increase danger of temporary blindness from lightning. Don t change power settings; maintain settings for the recommended turbulence penetration airspeed. Do maintain constant altitude; let the aircraft ride the waves. Maneuvers in trying to maintain constant altitude increase stress on the aircraft. Don t turn back once you are in the thunderstorm. A straight course through the storm most likely will get you out of the hazards most quickly. In addition, turning maneuvers increase stress on the aircraft. 20

25 AIRMET Geographic Areas of Responsibility Each area of responsibility issues its own set of AIRMET Bulletins AIRMETs (WA) Z, T, S (Airmen s Meteorological Information) Bulletins are issued every six (6) hours: Daylight Savings Time Standard Time 0145Z 0745Z 1345Z 1945Z 0245Z 0845Z 1445Z 2045Z AIRMET Bulletins contain AIRMETs describing the occurrence of (or the expected occurrence of) widespread adverse weather in the form of icing (AIRMET Z - ZULU), turbulence, low-level wind shear, strong surface winds (AIRMET T - TANGO), IFR conditions and mountain obscuration (AIRMET S - SIERRA). See the next 3 pages for a discussion of each series Are There Any AIRMETs? Examine AIRMETs ZULU, TANGO, and SIERRA to determine if they may be pertinent to your route of flight and your aircraft capability & equipment, or to your capabilities. AIRMETs concern less severe weather than that of SIGMETs or Convective SIGMETs. AIRMETs are in-flight advisories concerning adverse weather conditions of interest to all aircraft, and potentially hazardous to aircraft with limited capability due to lack of proper equipment, instrumentation, or pilot qualifications. The adverse conditions of AIRMETs affect (or are forecast to affect) an area of at least 3,000 square miles in size. It s possible that only a portion of the total area is affected at any one time. The question is, will you encounter these adverse conditions at the time and location they occur, when you are at that same time, location, and altitude? Altitudes in AIRMETs are 3 digit, referenced to Mean Sea Level (MSL). e.g. 080 Flight Levels (FL) are used for heights at or above 18,000 feet. e.g. FL210 If a SIGMET is also in effect, a reference will be made for the similar adverse conditions covering the affected area. e.g. SEE SIGMET BRAVO SERIES. Review the SIGMET! An AIRMET s valid time period is the same as an AIRMET Bulletin s valid time period (6 hours), unless it is otherwise noted in the AIRMET. Unscheduled AIRMETs may be issued as updates to AIRMET Bulletin s scheduled times, if necessary. UPDT will be added to the line containing the affected states. Even though the issue time of the updated AIRMET changes, the ending valid time remains the same. If an AIRMET is amended, AMD will be added after the date/time group of the AIRMET. If an AIRMET contains errors, it is corrected by adding COR after the date/time group. UPDT will be added to the line with the affected states. The AIRMET s issuance time will be updated, but the ending valid time will remain the same. An AIRMET can also be corrected and amended at the same time denoted by COR/AMD. When an AIRMET s adverse conditions are expected to develop during the 6 hour period after the ending valid time of a current AIRMET, an OUTLOOK is provided. Watch for these outlooks if you are taking an early look at the weather and plan to fly at a later time. AIRMETs Z, T, S Cover: (Z) Moderate Icing (T) Moderate Turbulence (T) Sustained Surface Winds of 30 Knots or More (T) Low Level Wind Shear Below 2,000 Feet AGL (S) Widespread areas of ceilings less than 1,000 feet and/or visibility less than 3 statute miles (S) Widespread or Extensive Mountain Obscuration AIRMET Information: 1. Location Using 3-letter identifiers, or well known geographic features or locations. 2. Condition and description, e.g. MOD TURB 3. Altitude or vertical extent, if appropriate. 4. Expected beginning and ending time of condition. 5. Remarks : Stating if the condition is expected to continue after the valid time of the AIRMET. 21

26 AIRMET ZULU (WA - Z) Plotted AIRMET ZULU Describes moderate icing MOD ICE AIRMET ZULU does not indicate whether icing is in clouds or in precipitation, or the type of icing, i.e. rime / mixed / clear. If the freezing level is at the surface, it will be defined by the contraction SFC. Airmet ZULU provides the lowest freezing level above the surface (SFC). Freezing levels aloft are referenced by high altitude VORs at 4,000 foot intervals MSL. Areas of multiple freezing levels are also referenced by high altitude VORs. 1 BOSZ WA AIRMET ZULU UPDATE 3 FOR ICE AND FRZLVL VALID UNTIL AIRMET ICE NY PA OH MI LE WV MD 4 FROM BUF TO 50E EKN TO CVG TO FWA TO DXO TO BUF 5 MOD ICE BTN 030 AND 100. CONDS CONTG BYD 03Z THRU 09Z. Example AIRMET ZULU The AIRMET ZULU example, above, is decoded line-by-line as follows: 1. BOS = AIRMET geographic area of responsibility identifier. Z = AIRMET series (ZULU for icing). WA = Product type: AIRMET = Date/time issuance time in UTC. 2. AIRMET = Product type. ZULU = AIRMET series. UPDATE 3 = Update number. FOR ICE AND FRZLVL = Product description. VALID UNTIL = Ending date/time in UTC of the AIRMET, not necessarily of the adverse conditions. 3. AIRMET ICE NY PA OH LE WV MD = Product type/series and phenomenon location by states (The coverage in each state may be all or a portion of the state). 4. FROM BUF TO 50E EKN TO CVG TO FWA TO DXO TO BUF = Phenomenon location by VOR locations. 5. MOD ICE BTN 030 AND 100. CONDS CONTG BYD 03Z THRU 09Z = This is the phenomenon description and time period the phenomenon is in effect (notice the words BYD and THRU ). Always check the adjoining geographic areas of responsibility for AIRMETs describing adverse conditions to determine if they may continue along your extended route of flight. Generally, an icing threat exists when flight altitude is at, near or above the freezing level and visible moisture is present or forecast along your route. Remember your pitot heat! Other than clear skies, the ideal winter flying scenario to minimize the icing threat is: High cloud bases, low cloud tops, low terrain, daylight flight, no low IFR conditions. TIPS: Watch your OAT. The basic icing temperature ranges are +1 to -10 degrees C for clear icing, and -10 to -20 degrees C for rime icing when flying in clouds. Have an alternative plan if you encounter these temperature ranges. Don t fly into areas of rain when the air temperature is near freezing. Ice can form on the windshield, impairing forward vision and, of course, airframe icing can occur, too. AIRMET OUTLOOKs: When an AIRMET s adverse conditions are expected to develop during the 6 hour period after the ending valid time of the current AIRMET, this information is included in a section called the: Outlook (OTLK) Watch for these outlooks in AIRMETs if you are taking an early look at the weather and plan to fly at a later time. 22

27 AIRMET TANGO (WA T) Describes: Moderate turbulence MOD TURB Low-level wind shear LLWS: Non-convective LLWS potential below 2,000 ft. Will include a list of the affected states and will be bounded by high altitude VOR locations. Sustained surface winds greater than 30 knots: STG SFC WND Plotted AIRMET TANGO Cause and direction of winds will not be given. 1 CHIT WA AIRMET TANGO UPDATE 3 FOR TURB VALID UNTIL AIRMET TURB MN ND SD NE 4 FROM BJI TO OBH TO BFF TO 50NNW ISN TO BJI 5 MOD TURB BLW 120. CONDS CONTG BYD 03Z THRU 09Z. Example AIRMET TANGO The AIRMET TANGO example, above, is decoded line-by-line as follows: 1. CHI = AIRMET geographic area of responsibility identifier. T = AIRMET series (TANGO - turbulence/low-level wind shear/strong surface winds). WA = Product type: AIRMET = Date/time issuance time in UTC. 2. AIRMET = Product type. TANGO = AIRMET series. UPDATE 3 = Update number. FOR TURB = Product description. VALID UNTIL = Ending date/time in UTC of the AIRMET, not necessarily of the adverse conditions. 3. AIRMET TURB MN ND SD NE = Product type/series and phenomenon location by states (The coverage in each state may be all or a portion of the state). 4. FROM BJI TO OBH TO BFF TO 50NNWISN TO BJI = Phenomenon location by VOR locations. 5. MOD TURB BLW 120. CONDS CONTG BYD 03Z THRU 09Z = This is the phenomenon description and time period the phenomenon is in effect (notice the words BYD and THRU ). Knowing where to expect turbulence helps you to avoid or minimize turbulence hazards or discomfort. AIRMET TANGO paints areas of occurring or expected turbulence with the stroke of a broad brush. The only reliable and accurate way to confirm the existence or absence of turbulence in an advisory area, for your fellow pilots, is to take a moment to make a pilot report to Flight Watch on frequency 122.0, or to flight service on TIPS: The first rule to follow when encountering turbulence is to alter airspeed. Know your aircraft operating manual s recommended turbulence penetration airspeed. Flying in mountain passes and valleys is not a safe practice during high winds. The mountains funnel the wind in these passes and valleys, thus increasing wind speed and intensifying turbulence. AIRMET OUTLOOKs: When an AIRMET s adverse conditions are expected to develop during the 6 hour period after the ending valid time of the current AIRMET, this information is included in a section called the: Outlook (OTLK) Watch for these outlooks in AIRMETs if you are taking an early look at the weather and plan to fly at a later time. 23

28 AIRMET SIERRA (WA S) Describes widespread IFR conditions and/or extensive mountain obscuration: Ceilings less than 1,000 feet: Plotted AIRMET SIERRA IFR, CIG BLW and/or - Visibility less than 3 statute miles: IFR, VIS BLW 3 SM BR ( BR in this example is mist) - and/or - Widespread mountain obscuration: MTN OBSCN or MTOS 1 SLCS WA AIRMET SIERRA UPDATE 3 FOR IFR AND MTN OBSCN VALID UNTIL AIRMET MTN OBSCN ID MT WY NV UT CO 4 FROM SHR TO DEN TO BCE TO BAM TO SHR 5 MTNS OCNL OBSC BY CLDS/PCPN/BR/FG. CONDS CONTG BYD 03Z THRU 09Z. Example AIRMET SIERRA The AIRMET SIERRA example, above, is decoded line-by-line as follows: 1. SLC = AIRMET geographic area of responsibility identifier. S = AIRMET series (SIERRA for IFR conditions and mountain obscuration). WA = Product type: AIRMET = Date/time issuance time in UTC. 2. AIRMET = Product type. SIERRA = AIRMET series. UPDATE 3 = Update number. FOR IFR AND MTN OBSCN = Product description. VALID UNTIL = Ending date/time in UTC of the AIRMET, not necessarily of the adverse conditions. 3. AIRMET MTN OBSCN ID MT WY NV UT CO = Product type/series and phenomenon location by states (The coverage in each state may be all or a portion of the state). 4. FROM SHR TO DEN TO BCE TO BAM TO SHR = Phenomenon location by VOR locations. 5. MTNS OCNL OBSCD BY CLDS/PCPN/BR/FG. CONDS CONTG BYD 03Z THRU 09Z = This is the phenomenon description and time period the phenomenon is expected to be in effect (notice the words BYD and THRU ). Understand the Hazards of Mountain Obscuration: The term Mountain Obscuration is used to describe visibility conditions different than IFR caused by low ceilings above ground level. In mountainous terrain, where weather reporting stations may be in the valleys, the cloud layers above the reporting stations may be below the mountain tops, thereby obscuring the higher terrain in cloud cover. Always compare highest terrain features along your route of flight with reporting stations. In mountainous terrain, weather reported as VFR may be impassable by VFR flight rules. AIRMET SIERRA Contractions: Weather & obstructions to visibility include: CLDS (clouds) PCPN (precipitation) FU (smoke) HZ (haze) BR (mist) FG (fog) BLSN (blowing snow) AIRMET OUTLOOKs: When an AIRMET s adverse conditions are expected to develop during the 6 hour period after the ending valid time of the current AIRMET, this information is included in a section called the: Outlook (OTLK) Watch for these outlooks in AIRMETs if you are taking an early look at the weather and plan to fly at a later time. 24

29 Plotted SIGMET XRAY 6 SIGMET Geographic Areas of Responsibility Each area issues its own set of SIGMETS 1 SFOX WS SIGMET XRAY 6 VALID UNTIL SIGMET 4 CA 5 FROM EHF TO TRM TO MZB TO LAX TO 40W RZS TO EHF 6 OCNL SEV TURB BLW 120. CONDS CONTG BYD 0050Z SIGMETs Significant Meteorological Information: Expected or occurring having a significant effect on the safety of aircraft operations. SIGMETs Describe: Severe Turbulence SEV TURB. Extreme Turbulence XTRM TURB. Clear Air Turbulence CAT. Mountain Waves. Severe Icing SEV ICE. Widespread Duststorm WDSPR DS. Widespread Sandstorm WDSPR SS. Tropical Cyclone TC and Volcanic Ash VA. Example SIGMET XRAY 6 Are There Any SIGMETS? The SIGMET XRAY 6 example, above, is decoded line-by-line as follows: 1. SFO = SIGMET geographic area of responsibility identifier. X = SIGMET series (XRAY). WS = Product type: SIGMET = Date/time issuance time in UTC. 2. SIGMET = Product type. XRAY = SIGMET series. 6 = Issuance number (Sixth SIGMET issued since 0000Z on the17 th day of this month). VALID UNTIL = Ending date/time in UTC of this SIGMET XRAY 6, not necessarily of the adverse conditions (in this example, turbulence). 3. SIGMET = Product Type. 4. CA = Location by states (Coverage in each state may be all or a portion of the state). 5. FROM EHF TO TRM TO MZB TO LAX TO 40W RZS TO EHF = Phenomenon location by VOR locations. 6. OCNL SEV TURB BLW 120. CONDS CONTG BYD 0050Z = This is the phenomenon description and time period the phenomenon is in effect (notice the word BYD. There will likely be a SIGMET XRAY 7 issued later). SIGMETs advise of nonconvective weather that is potentially hazardous to all aircraft. No two different hazardous weather phenomena across the country requiring the issuance of a SIGMET will have the same alphabetic designator. As a SIGMET continues to be updated, and it moves across the country, the geographic area of responsibility identifier will change, and the issuance number will increase. For example, if the SFO SIGMET XRAY 6 (above) moves eastward into the SLC area, it will be designated SLC SIGMET XRAY 7 when it is updated again. Widespread dustorms (WDSPR DS ) and widespread sandstorms (WDSPR SS) meet SIGMET criteria when surface or inflight visibilities become below 3 statute miles. The only reliable and accurate way to confirm the existence or absence of the hazardous conditions in SIGMETS, for your fellow pilots, is to take the time to make a pilot report.. SIGMET Issuances: A first SIGMET issuance will be labeled as UWS for Urgent Weather SIGMET. Subsequent SIGMETs are at the forecaster s discretion, as a WS and will be numbered sequentially until the adverse phenomenon ends. SIGMETs are identified by an alphabetic designator from November through Yankee. (Sierra, Tango, and Zulu are reserved for the AIRMETs). Time and Coverage Maximum forecast period for a SIGMET is four hours. SIGMET conditions are considered to be widespread because they must cover an area of at least 3,000 square miles (mountain waves don t have to meet this criteria). Keep in mind, however, the area affected may be only a small part of the total area at any one time. 25

30 Center Weather Service Unit (CWSU) Areas of Responsibility Are There Any Center Weather Advisories? [Issued by the Center Weather Service Unit (CWSU)] Center Weather Advisory (CWA) Issued by Center Weather Service Units. Valid for up to two hours may include forecasts of conditions expected to begin within two hours of issuance and beyond the two hour valid period. Additional CWAs will be issued as required. The CWA is an aviation weather warning message for conditions approaching or meeting the criteria of AIRMETs, SIGMETs, or CONVECTIVE SIGMETs. Urgent Center Weather Advisories (UCWA) may be issued when adverse weather has an immediate effect on ARTCC air traffic. 1 ZME3 CWA ZME CWA 303 VALID TIL FROM MEM TO JAN TO LIT TO MEM 4 OCNL TS MOV FM 24025KT. TOPS TO FL430 SAME MOVMT EXPD DRG THE NEXT 2 HRS. Example Center Weather Advisory (CWA) Decoded CWA, Line by Line: 1. ZME = ARTCC CWSU Identification (Memphis). 3 = Phenomenon Number (single digit, 1 6). CWA = Product Type (UCWA or CWA) = Beginning and/or Issuance UTC date/time. 2. ZME = ARTCC CWSU Identification (Memphis). CWA = Product type (UCWA or CWA). 3 = Phenomenon Number (single digit, 1 6). 03 = Issuance Number (issued sequentially for each Phenomenon Number). VALID TIL = Ending valid UTC date/time. 3. FROM MEM TO JAN TO LIT TO MEM = Location of the Phenomenon within the described reference points. 4. OCNL TS MOV FM 24025KT. TOPS TO FL430 SAME MOVMT EXPD DRG THE NEXT 2 HRS = The Description of the Phenomenon. CWAs are issued in the four following situations: CWSU Identifiers ZAB Albuquerque ZAU Chicago ZBW Boston ZDC Washington ZDV Denver ZFW - Fort Worth ZHU Houston ZID Indianapolis ZJX - Jacksonville ZKC - Kansas City ZLA - Los Angeles ZLC - Salt Lake City ZMA Miami ZME Memphis ZMP Minneapolis ZNY - New York ZOA Oakland ZOB Cleveland ZSE - Seattle ZTL - Atlanta 1. Preceding an advisory (AIRMET, SIGMET, CONVECTIVE SIGMET). An Urgent CWA (UCWA) can be issued to expedite dissemination, if necessary. 2. To refine an existing AIRMET, SIGMET, CONVECTIVE SIGMET concerning location, movement, extent, or intensity of the weather event pertinent to the CWSU area of responsibility. 3. To highlight significant weather not meeting AIRMET, SIGMET, or CONVECTIVE SIGMET criteria that might adversely impact the CWSU area of responsibility. 4. To cancel a CWA when the weather described in a CWA is no longer expected. A CWSU meteorologist may issue hourly CWAs for convective activity impacting the safe flow of air traffic. Significant weather changes described in an earlier CWA will be updated by another CWA describing the latest adverse weather phenomena. The CWA can be used for the planning and avoidance of adverse weather during your flight in the en route and terminal environments. Meteorological Impact Statement (MIS) Though not intended for pilot weather briefing, the MIS can offer good information about expected hazardous weather. The MIS is an unscheduled flight operations and flow control planning forecast to help ARTCC personnel make flow control decisions. The MIS can also be accessed on the CWA web site. 26

31 Adverse Conditions: Use The FAA Standard Weather Briefing Format As Your Guide In This Way, You Will: 1.) Cover all Weather Details. 2.) Develop Consistency. 3.) Enhance Understanding. 4.) Increase Retention. 5.) Know where to instantly look at your notes for a quick review. It s Time for the Details! Okay. So you ve got the Big Picture for your route of flight from your study of the charts. Now it s time to delve into the details and get down to the specifics. Appendix A offers a master you can duplicate at your local copy shop so you have a fresh form for recording your weather data for each flight. An enlarged form is also included for you big writers and for use during the more complex weather events where more writing is likely. This form is arranged in the sequence you will follow during each successive page of this manual. Flight service pilot weather briefers are trained to provide weather information in this sequence, too. So, if you alternate between briefing yourself and receiving a flight service briefing, the order of information will remain constant. The advantage to following this standard format is the development of consistency in reviewing your weather data. Over time, your self briefing habit pattern will become so well ingrained that if you miss reviewing a weather item, it will be noticeable to you. Your self briefings will become easier, too, with your developed familiarity with the standard format. Use the weather brief form as you proceed through the remaining pages of this manual, jotting down the weather data which will give you a total understanding of the current and forecast weather, as well as the hazardous conditions expected along your proposed route of flight. TIP: The AOPA offers a handy Flight Planner printable form on their web site. To access, go to Hover your mouse pointer over the AOPA Air Safety Institute button. On the dropdown menu, click on Safety Publications/Articles. Click on: Flight Planner Form. You can then print the form with your computer s print command. Standard Briefing: Synopsis Adverse Conditions Current Conditions Departure Forecast Enroute Forecast Destination Forecast Winds & Temperatures Aloft NOTAMs and TFRs! 27

32 SYNOPSIS Write a synopsis on the weather brief form. (Review page 3, if you wish.) The synopsis is a brief verbal description of the Surface Analysis Chart outlining dominate features and weather generators. You can obtain your synopsis in two ways: Area Forecast (FA) Areas of Responsibility Read the Area Forecast (FA) synopsis (web site url: for the area involving your flight. - and/or - Examine the Surface Analysis Chart and create your own synopsis based on your study of the pressure and frontal systems. Why Are There Different Synopses in Area Forecasts? Surface Analysis Chart SYNOPSIS In your examination of the Surface Analysis Chart earlier (see page 3), you developed a big picture of the weather makers. Now, review the Surface Analysis Chart, Surface Prog, and Significant Weather Prog Charts (pages 5 and 6) once more with an emphasis on the positions of the highs, lows, troughs, ridges, and frontal systems on each chart. Study how they tend to progressively move on each successive forecast chart with the passage of time. If you are planning a long distance flight, or a turn-around flight later on, this examination will give you a general idea of the trend of weather you can expect for your flights. Some general weather characteristics a synopsis can reveal: If your flight takes you toward a low or a front, conditions will likely deteriorate as you get closer. Cloud tops will likely be higher. Expect cloud bases to get lower. At the lower altitudes anticipate turbulence as you approach the low and/or frontal system. Low pressure systems rotate counter-clockwise and draw air upwards. Surface lows tend to move with the wind flow at 18,000 feet. The prog charts clearly reveal this movement. Cold fronts = unstable air, cumuluform clouds, showery precipitation, turbulence, possible thunderstorms. Warm fronts = stable air, stratus clouds, steady precipitation, widespread low ceilings and visibilities, possible embedded thunderstorms. These general tendencies vary, considering the multitude of variables involved in the mix of weather makers. Strength and movement of pressure systems, moisture content of air masses, temperatures, frontal characteristics (strong, weak, diffuse, increasing/decreasing in strength, time of day, etc.) all interrelate to create weather dynamics that challenge even the most capable meteorologists in their attempt to accurately forecast the weather. Each Area Forecast contains a Synopsis. The Synopsis will be worded differently in each Area Forecast because meteorologists creating the synopsis for each region will concentrate on the pertinent weather features affecting their specific geographic area of responsibility (See Area Responsibility chart, above). Weather Maps: You may find the weather maps on the morning TV shows helpful in getting an overview of the weather. But never rely on them alone. They only give a non-specific picture of the general weather covering the entire day. Always examine the synoptic aviation charts prior to your flight to appraise the current and forecast weather makers at specific times of the day. 28

33 Icing Durations, Intensities, and Types: Duration: Occasional Less than 1/3 of the time. Intermittent 1/3 to 2/3 of the time. Continuous More than 2/3 of the time. Intensity: Trace Ice becomes perceptible. Rate of accumulation slightly greater than rate of sublimation. It is not hazardous even though deicing/antiicing equipment is not utilized, unless encountered for an extended period of time (over 1 hour). Type: Light -- The rate of accumulation may create a problem if flight is prolonged in this environment (over 1 hour). Occasional use of deicing/ anti-icing equipment removes/prevents accumulation. It does not present a problem if the deicing/anti-icing equipment is used. Moderate The rate of accumulation is such that even short encounters become potentially hazardous and use of deicing/anti-icing or diversion is necessary. Severe The rate of accumulation is such that deicing/anti-icing equipment fails to reduce or control the hazard. Immediate diversion is necessary. Heavy This intensity term does not officially exist. It is improperly used. The wording of Heavy, indicates Severe Icing. Clear Icing / Rime Icing / Mixed Icing Adverse Conditions Icing Enter onto the weather brief form, the data you find about the pertinent icing conditions in AIRMETs, SIGMETs, and CWAs: Note the: Advisory name, alphabetic designator, update number, and effective timeframes. Freezing level. Intensity of icing. Vertical extent of the icing (bases and tops). Icing condition ending time. Geographic locations. Check for an Outlook portion to advisories. Is Icing Going to be a Factor? Look over the AIRMETs, SIGMETs, and CWA a (if any) to see if icing is going to be a consideration for your flight. The map displays of the AIRMETs and SIGMETs offer a quick glimpse of the affected areas relative to your route of flight. However, be sure to study the textual information of these advisories to get the details on how the icing threat may affect your aircraft. If you wish, review AIRMETs, SIGMETs, and CWAs on pages 21 through 26. Cloud Types and Icing: In stratiform clouds, rime icing is most likely. The icing may also extend great distances horizontally. Requesting an altitude change from ATC may or may not alleviate the icing condition. It may, however, take you out of the clouds. An altitude change to warmer air with above freezing temperatures is obviously a good choice. In cumuliform clouds, clear icing can be expected. Brief and rapid accumulations are likely, especially in the temperature range from 0 degrees to minus 10 degrees Celsius. Changing your flight path, as opposed to an altitude change, and getting out of the clouds into visual conditions is your best alternative to relieve clear icing conditions. Freezing rain should be avoided at all times. If you encounter freezing rain, the old rule of thumb to climb to warmer air may not be a good course of action. How far above you is that warmer air in the overriding front? Does your aircraft have sufficient power to climb with the added weight, drag, and reduced power & lift caused by the icing accumulation? Icing Types: Clear Ice is hard, heavy, and tenacious. Removing clear ice with deicing equipment is especially difficult. If boots are prematurely inflated, clear ice can form which would be impossible to remove. Clear ice forms in cumuliform clouds and in rain. Rime Ice is irregular in shape, has a rough surface, and is white in color much like the ice that forms inside a freezer. Its irregular shape and roughness reduces the aerodynamic efficiency of your aircraft by reducing lift and increasing drag. Rime ice is quite brittle and is easier to remove than clear ice. Current Icing Potential (CIP): The CIP provides a detailed, hourly 3-dimensional look at inflight icing conditions and the potential for super cooled liquid droplets. FAA policy is that this is a supplementary weather product for enhanced situational awareness and it must be used with the other primary weather products, ie., AIRMETs and SIGMETs. Access this great info at : click on the Icing link. Forecast Icing Potential (FIP): Complementing the CIP at the same web site, the FIP is used to supplement AIRMETs and SIGMETs by identifying areas of forecast icing potential, but it does not substitute for the intensity and forecast details contained in AIRMETs and SIGMETs. It is authorized for operational use by meteorologists and dispatchers, only. Mixed Ice is clear and rime icing mixed together with large and small water droplets or even snow combining. It can form quite rapidly into a rough accumulation, sometimes forming an aerodynamically inefficient mushroom shape on the leading edges of airfoils. 29

34 Duration: Occasional Less than 1/3 of the time. Intermittent 1/3 to 2/3 of the time. Continuous More than 2/3 of the time. Adverse Conditions Turbulence Enter onto the weather brief form, the data you find about the pertinent turbulence conditions you find in AIRMETs, SIGMETs, and CWAs: Note the: Advisory name, alphabetic designator, update number, and effective timeframes. Intensity of the turbulence. Direction of the wind flow. Vertical extent of the turbulence. Turbulence ending time. Geographic locations. Check for an Outlook portion to advisories. U.S. Government Image Is Turbulence Going to be a Factor? Look over the AIRMETs, SIGMETs, and CWAs (if any) to see if turbulence is going to be a consideration for your flight. The map displays of the AIRMETs and SIGMETs offer a quick glimpse of the affected areas relative to your route of flight. However, be sure to study the textual information of these advisories to get the details on how the turbulence may affect your aircraft. If you wish, review AIRMETs, SIGMETs, and CWAs on pages 21 through 26. As stated earlier during the AIRMET TANGO discussion, the AIRMET paints areas of occurring or expected turbulence with the stroke of a broad brush. The entire advisory area is not necessarily totally affected at all times by the turbulence hazard. When approaching a mountain during strong, turbulent wind conditions, approach it at a 45 degree angle, so that only a 45 degree turn away from the ridge line is required to abort your ridge crossing attempt. if necessary. Where you can expect to encounter Moderate Turbulence: In mountainous areas with knot winds perpendicular to the ridges. Within 5,000 feet AGL when surface winds exceed 25 knots. In areas of strong surface heating (over darker terrain that absorbs the sun s rays). In the boundary area of a strong inversion. When vertical wind shear exceeds 6 knots per 1000 feet (examine the winds aloft for this). Where you can expect to encounter Severe Turbulence: In mountainous areas with 50 knot winds perpendicular to the ridges. Within 5,000 feet above the ridge, and at and below the ridge in rotor clouds or action. In towering cumulus clouds. In and near developing and mature-state thunderstorms. When vertical wind shear exceeds 6 knots per 1000 feet (examine the winds aloft for this). Where you can expect to encounter Extreme Turbulence: In mountain wave action when in and below well-developed rotor clouds. The extreme turbulence may extend all the way down to the surface. In developing or mature severe thunderstorms, and in and near squall lines with all the elements of severe convective activity continuous lightening, ¾ hail, winds of 50 knots, or greater, highest intensity weather-radar echoes. Comfort Tips: For greater passenger comfort on hazy summer days, flying above the haze layer will tend to smooth out the bumps. Climbing above the cumulus clouds will smooth out your ride. Tops in the summer may be too high. Cloud tops in the winter tend to be lower. Be careful that you don t get caught on top of an overcast! Fly early or late to avoid the most turbulent summer time surface heating updrafts. Severe to Extreme Turbulence Tips: Always secure loose objects. Disengage autopilot, if in use. Don t chase airspeed. Don t chase altitude. Fly attitude, not altitude. Avoid abrupt maneuvering. In general, don t be concerned by altitude changes unless terrain avoidance becomes an issue, or you wrongly fly on the semi-circular altitudes. 30

35 Adverse Conditions - IFR Conditions and/or Mountain Obscuration Enter onto the weather brief form, the data you find about the pertinent low weather conditions you find in AIRMETs, & CWAs: Mountains Obscured by Clouds (most common obscuration advisory is due to clouds, precipitation, mist, and fog CLDS PCPN BR FG) Note the: Advisory name, alphabetic designator, update number, and effective timeframes. Low ceiling and visibility restriction causes. Mountain obscuration causes. Geographic locations. Check for an Outlook portion to advisories. Will IFR Conditions or Mountain Obscuration be a Factor? Look over the AIRMETs, CWAs (if any), and Weather Depiction Chart to see if IFR conditions and/or mountain obscuration are going to be a concern for your flight. The map displays of the AIRMETs offer a quick glimpse of the affected areas relative to your route of flight. However, be sure to study the textual information of these advisories to get the details on how the IFR conditions and/or mountain obscuration may impact your flight. If you wish, review AIRMETs & CWAs on pages 21 through 26, and the Weather Depiction Chart on page 2. Types of FOG: Precipitation Induced Fog forms when warm rain falls through cooler air. It extends over large areas, is commonly associated with warm fronts, and sometimes slow moving cold fronts and stationary fronts. This fog can be quite dense and continue for extended periods of time. Stratus clouds frequently occur with this fog, forming scud clouds or sometimes blending together where there is no distinction between the fog and stratus. Advection Fog occurs when warm, moist air moves over colder air. It is common along coastal areas, such as the California coast and, in the winter, over the central and eastern United States when warm, moist air from the Gulf of Mexico moves northward. Upslope Fog forms when warm, moist air flows toward higher terrain. This type of fog is common along the eastern slopes of the Rocky Mountains. It can form under cloudy skies. It is often quite dense, and can extend upslope to high altitudes. Radiation Fog is common in the fall, forming overnight or around sunrise, when the skies are clear and winds are light. The fog sometime becomes more dense or forms after sunrise. It is also called ground fog, and sometimes called valley fog. Radiation fog tends to burn off by mid to late morning. If it is extremely widespread it can persist for an even longer time, slowly dissipating from the outside edges shrinking inward. Steam Fog Forms as cold air moves over warm water. The evaporating warm water immediately condenses in the cool air just above it. For all types of fog expect little if any improvement in visibility when fog exists below heavy, overcast conditions, especially when rain, snow, or drizzle is occurring or forecast to continue. Keep in mind, drizzle and snow restrict visibility to a greater degree than rain. Temperature and Dewpoint Spread: The temperature/dew point spread will decrease as the temperature lowers, typically at night and in the very early morning. Fog is most likely to occur at these times, and can form rapidly shortly after sundown or around sunrise. Fog is likely to form when the temperature/dewpoint spread is small and is decreasing. Fog Burn Off Fog tends to burn off in the morning when the rising sun heats the air, increasing the temperature/dewpoint spread which vaporizes the moisture in the air (fog). Burn off typically begins on the outside edges, shrinking inward. However, if there is a higher overcast layer of clouds on a foggy morning, burn off is inhibited and the fog will not dissipate as quickly. 31

36 Adverse Conditions Thunderstorms Enter onto the weather brief form, the data you find about the pertinent thunderstorm conditions found in Convective SIGMETs, CWAs, AWWs, WWs, WSR-88D Radar, the Radar Summary Chart, Satellite Imagery: Note the: Advisory names, alphabetic designators, update numbers, and effective timeframes. Intensity of the thunderstorms. Direction and speed of movement. Vertical extent of the thunderstorms (tops). Thunderstorm ending times. Geographic locations. Check for an Outlook portion to advisories. U.S. Government Image Will Thunderstorms be a Factor? Look over the WSR-88D Radar, Radar Summary Chart, Satellite Imagery, Convective Sigmets, Severe Weather Watches, and CWAs (if any), to see if thunderstorms are going to be a threat to your flight. The map displays of the Convective SIGMETs and Severe Weather Watches offer a quick glimpse of the affected areas relative to your route of flight. However, be sure to study the textual information of these advisories to get the details on how thunderstorms may affect you. If you wish, review the WSR-88D Weather Radar (pages 13-16), Radar Summary Chart (page 12), Satellite Imagery (page 4), Convective Sigmets (page 19), Severe Weather Watches (page 18), and CWAs (page 26). Use the web site url s noted on the above pages, if you don t have these web sites (or your favorites) bookmarked. Thunderstorm Avoidance: Frequent lightning indicates a severe thunderstorm. Any thunderstorm topping out at over 35,000 feet is extremely hazardous. The gust front of a thunderstorm is defined by a line of dust and debris blowing along the surface. Do not take off or land in the vicinity of an approaching thunderstorm or squall line. Do not fly under a thunderstorm even if it s not raining and you can see to the other side of the thunderstorm. Severe turbulence/updrafts/downdrafts/downbursts are likely. Also, evaporating rain (virga) falling from high based thunderstorms causes violent downdrafts. Don t be tempted to fly through a narrow cloud free space between two thunderstorms. The turbulence may be quite severe in this area. Severe turbulence can be expected up to 20 miles from severe thunderstorms, and it will be greater downwind of the thunderstorm. Don t fly into clouds containing embedded thunderstorms without airborne weather radar. Thunderstorm Dangers: Vertical Updraft/Downdraft Windshear overstresses aircraft or causes loss of control. Heavy Rain reduces approach/landing visibility, and my cause rollout hydroplaning. Wind Gusts Rapid wind speed and direction changes make takeoff/landing dangerous. Hail may even be encountered in clear air away from the thunderstorm if it is thrown outward and upward from active thunderstorm cells. Barometric Pressure rapidly fluctuates, causing altimeter readings to be unreliable. Lightning Strikes can happen even if your airplane is flying in clear air near the storms. The NCWF: The National Convective Weather Forecast (NCWF) is a diagnostic and forecast tool using radar data, echo top mosaics, and lightning data to determine the expected movement of thunderstorm cells over the upcoming hour. The NCWF, an unofficial product, is a supplement and is not a substitute for the information contained in the Convective Sigmets. The CCFP: The Collaborative Convection Forecast Product is used by ATC flow control specialists as a planning tool. The CCFP predicts thunderstorm area coverage two, four, and six hours into the future. It is issued every two hours, eleven times a day. It is not to be used for weather briefing. 32

37 Adverse Conditions - Other Potential Hazards Enter onto the weather brief form, any other adverse conditions affecting your flight, such as: Adverse Terrain Mountains Large Bodies of Water Known Obstructions-Towers / Wires Poor Visibilities in Haze Night Flight VFR in Congested Areas Will any Other Adverse Conditions Affect My Flight? Mountain Flying: A marginal VFR weather forecast is likely to produce areas of IFR in the mountains. If forecast winds aloft exceed 25 knots below 12,000 feet, the wind velocity may be twice as strong in or near mountain passes creating dangerous up drafts and down drafts. Plan your over mountain flight for the early morning or evening hours. Turbulence is typically greatest from mid-morning through early evening. Keep your aircraft as light as possible to increase aircraft performance in the high density altitude environment in the mountains. Remember, the most adverse conditions for aircraft performance are high altitude, high gross weight, and high ambient temperatures. Mountain winds follow contours like water in a stream. The wind flow on the downwind side of a mountain can be extremely turbulent. Fly on the upwind side, if possible. IFR flight in clouds and night flight over mountainous terrain is not a good practice. Night Landings with Deceptively Thin Fog: When looking down at an airport at night where you intend to land, a thin layer of fog is very deceptive from above where you can see the ground features and lights, But on final approach, when you enter the fog, all forward visibility may be lost. Be prepared to do a go-around with no hesitation if your visibility deteriorates during your approach. If you are caught in a deteriorating weather situation which causes you to fly at ever lower altitudes, be cautious of obstacle hazards, such as power lines and towers. It s best to fly directly over these structures since it s more difficult to determine your height above the nearly invisible wires strung between the towers. Communication towers sometimes have wires strung outward from them at about a 45 degree angle, so do not fly alongside them. VFR Hazardous Area Reporting Service: Flight Service can provide flight following for specified VFR flight routes charted over mountains, swamps, and large bodies of water. Radio contacts are expected every 10 minutes. If radio contact is lost for more than 15 minutes, Search and Rescue is alerted. Services offered include: Everglades Reporting, Great Lakes Reporting, and others. Contact a flight service station for details on your responsibilities and use of this service. Night Flying: Night flights don t allow you to see adverse weather ahead on your flight path. If VFR, clouds easily avoided during the day may not be seen at night until you fly into them. Flying at night over sparse terrain in heavy haze could lead to an attack of vertigo. If you notice surface lights twinkling, fog is beginning to form. Land at the nearest suitable airport while you still can. In-flight Visibilities: When flying in restricted visibility conditions, expect your slant-range visibility to be lower than the reported surface reported visibilities. This is especially true when flying towards the sun with haze conditions where surface visibilities are reported at 5 to 6 miles. Inflight visibility may be so severely reduced that it is unsafe for continued VFR flight. 33

38 VFR Flight Not Recommended (VNR) Include this statement when VFR flight is proposed and sky conditions or visibilities are present or forecast, that in your judgment would make flight under visual flight rules doubtful. Describe the conditions, affected locations, and times. Adverse Conditions. Include this element when meteorological or aeronautical conditions are reported or forecast that might influence the pilot to alter the proposed flight. Emphasize conditions that are particularly significant, such as low level wind shear, thunderstorms, reported icing, frontal zones along the route of flight, airport closures, air traffic delays, etc. Weather advisories (WS, WA, WST, CWA, and AWW) shall be given stating the type of advisory followed by the pertinent information. From the flight service Bible, the FAA Order VFR Flight Is It Advisable? The VNR statement given by flight service is advisory in nature. It has always been your decision to fly. Whether your flight can be conducted safely rests solely with you, the pilot. If you are uncomfortable with the weather, trust your instincts. If it does not feel right, Don t Go Go No Go Decision for VFR Rated Pilots: Based on your weather analysis so far, can you safely fly under Visual Flight Rules? If you are a VFR only rated pilot, the best way to make a sound go-no-go decision is to use the same standards that flight service pilot weather briefers employ when making the VFR Flight Not Recommended statement. Read carefully the excerpts from the flight service bible, above. Note the phrases, that in your judgment would make flight under visual flight rules doubtful and that might influence the pilot to alter the proposed flight True, enough, flight service pilot weather briefers may at times be overly conservative in issuing the VNR statement in our litigious times, which can lead to a degree of cynicism by a number of pilots. But it s ultimately your decision as to whether you can conduct your flight in VFR conditions with a good margin of safety. Using these flight service standards will give you a nice, solid foundation for making your decision. Safe flying depends on good decision making on your part where any doubtful weather information should influence you to cancel, alter, or delay your flight. With inadvertent entry into instrument meteorological conditions being a significant factor in VFR rated pilot accidents, adhering to the following DON Ts are a must: DON T DON T DON T DON T DON T DON T depart VFR when the weather is near or below VFR minimums. scud run, even if it s along a well known route. continue flight into deteriorating weather. underestimate the risks when flying in adverse weather. be overconfident in your ability to handle adverse weather. ever let peer pressure influence your decision making. Most importantly, flying VFR means staying visual. Don t allow yourself to be seduced into continuing forward into subtle, progressively lowering conditions until you suddenly find yourself in inadvertent instrument meteorological conditions. If you find yourself getting apprehensive or hoping things will get better if I go just a little farther, it is definitely time to discontinue your flight or turn around. And, finally, be proficient in conducting a standard rate 180 degree turn on instruments. Establish Your Own Personal Minimums: Develop your own personal weather minimums, higher than FAA minimums, based on your flight experience and comfort level. Have even higher minimums for night flight to give yourself added protection. Adhering to your personal minimums will ensure that you have a safe, enjoyable flight every time you fly. Area Forecast Trap! The setup No AIRMET Sierra for IFR conditions or mountain obscuration is in effect. However, the Area Forecast clouds and weather section does mention: VIS 3-5SM-SN BR Some pilots might think it s good enough to fly. But is it? Think again. 3 to 5 miles is very close to IFR conditions. You could easily blunder into un-forecast heavier snow. 34

39 METAR KSEA KT 290V360 1/2SM R31/2600FT +SN BLSN FG VV008 00/M03 A2991 RMK RAESNB42 SLPNO METAR aviation routine weather report KSEA Seattle,WA th day of the month, time 1545 UTC 33018KT wind 330 at 18 knots 290V360 wind direction variable between 290 and 360 degrees 1/2SM visibility one-half R31/2600FT runway 31, RVR 2600 feet +SN heavy snow BLSN FG blowing snow and fog VV008 indefinite ceiling /M03 temperature zero, dew point minus 3 A2991 altimeter 2991 RMK remarks (follow): RAESNB42 rain ended at four two, snow began at four two SLPNO sea-level pressure not available Current Conditions METARs and SPECIs A METAR is an aviation routine weather report. A METAR is an hourly scheduled observation of actual conditions measured at an airport or other designated observation point (a mountain pass). A SPECI is an unscheduled weather report issued when certain weather criteria have been observed. Many SPECIs might be issued during changeable weather conditions. See Appendix E for national maps and a decoder of TAF locations which include METAR reports. A Typical METAR, With Explanations What are the Observed Conditions Along My Route? Examine the METARs and SPECIs along and adjacent to your route of flight. Be sure to look closely at the reporting times of each report. The reports may not be listed in the proper time order. Rearrange these reports as you record them on your weather brief form to better see the weather trend and have them handy for review while enroute. Look at the intensities of reported precipitation (liquid and frozen). A minus sign indicates light precipitation, which usually means VFR variable MVFR visibilities. When moderate precipitation is occurring, you can expect MVFR to IFR visibilities. Heavy precipitation is indicated by a plus sign. IFR visibilities are a certainty with heavy precipitation. Look for thunderstorm clues in the Remarks section of the METARs and SPECIs, if they are not reported in the body of a report. BLDG CU, TCU, CB, DSNT LTG, TS are all indicators that thunderstorms are nearby and might have an impact on that station. A common quirk seen in METARs is when CLR (clear below 12,000) is reported as the sky condition, yet in Remarks, TSB01 TSE02 is annotated. Thunderstorm began at zero-one and thunderstorm ended at zero-two. Check the weather radar for confirmation, if you wish. A one-minute thunderstorm is highly unlikely especially with clear skies! METAR Format: The aviation routine reporting code called METAR contains the below elements in the order listed: 1. Type of Report 2. ICAO Station Identifier 3. Date and Time of Report 4. Modifier (as required) 5. Wind 6. Visibility 7. Runway Visual Range (RVR) 8. Weather Phenomena 9. Sky Conditions (AGL) 10. Temperature/Dew Point Group (Celsius) 11. Altimeter 12. Remarks (RMK) The above elements are separated with a space with the exception of temperature and dew point which are separated by a solidus ( / ). When an element does not occur or cannot be observed, the preceding space and that element are omitted from the METAR. TIP: When evaluating marginal weather reports, keep in mind that conditions between the reporting stations may be lower than reported. Weather is seldom uniform, even over short distances. This is especially true in areas of varying elevations and in remote locations with longer distances between reporting stations. High terrain between reporting stations would have lower AGL cloud bases. A METAR Trap: In the remarks section of a METAR, occasionally you may see the term TSNO. This remark does NOT mean there are no thunderstorms. TSNO means thunderstorm information is not available. Thunderstorms occurring at this METAR location would not be reported. If conditions are favorable for thunderstorm development, be sure to check other resources. 35

40 Current Conditions METARs and SPECIs Common METAR Terminology: Listed on this page are some common terms used in METARs and SPECIs. You should be able to interpret reports with the information provided here. If you wish to have a complete understanding, our other book, The METAR & TAF Quick Reference Manual will answer all of your questions. Weather and Obscurations Phenomena Include: Precipitation: DZ - Drizzle RA - Rain SN - Snow SG - Snow Grains IC - Ice Crystals PL - Ice Pellets GR - Hail GS - Small Hail or Snow Pellets UP - Unknown Precipitation Obscurations: BR - Mist FG - Fog FU - Smoke DU - Dust SA - Sand HZ - Haze PY - Spray VA - Volcanic Ash Other Types of Weather Phenomena: PO - Dust or Sand Swirls SQ - Squalls SS - Sandstorm DS - Duststorm FC - Funnel Cloud +FC - Tornado or Waterspout Qualifiers of Weather Phenomena: MI - Shallow BC - Patches DR - Low Drifting BL - Blowing SH - Showers TS - Thunderstorm FZ - Freezing PR Partial Intensity Qualifiers include: Light, denoted by Moderate, denoted by the lack of a symbol Heavy, denoted by + Proximity Qualifier "In the Vicinity" is denoted by VC Sky Conditions: Sky cover is reported in eighths of coverage (octas): Reportable Summation Contractions Meaning Amount VV Indefinite Ceiling 8/8 (vertical visibility) SKC or CLR Clear 0 or 0 below 12,000 FEW Few 0 to 2/8 SCT Scattered 3/8 to 4/8 BKN Broken 5/8 to 7/8 OVC Overcast 8/8 CB Cumulonimbus When present TCU Towering Cumulus When present Order of Remarks and Selected Contractions: Volcanic Eruptions Tornado (+FC), Funnel Cloud (FC) or Waterspout (+FC) Station Type (Automated A01 or A02) Peak Wind (PK WND) Wind shift (WSHFT), Frontal passage (FROPA) Tower visibility (TWR VIS) or Surface visibility (SFC VIS) Variable visibility (VRB VIS) Sector visibility (Sector VIS) Visibility at second site 2nd Site) Dispatch Visual Range Lightning (frequency of lightning, type and location) Beginning & ending of precipitation or thunderstorms Thunderstorm (TSTM) location and movement (MVMT) Hailstone (GR) size Virga (precipitation that does not reach the ground) Variable ceiling height (VRB CIG) Obscuration Variable (VRB) sky condition Significant Cloud types (CB, CBMAM, TCU, SCSL) Sky cover at second site 2nd Site) Pressure falling rapidly (PRESFR) Pressure rising rapidly (PRESRR) Sea-level pressure (SLP) Aircraft Mishap (ACFT MSHP) No Special weather report (NOSPECI) Snow Increase (SNINCR) Other Significant (SIG) information 36

41 SGF UA/ OV SGF /TM 1550 /FL030 /TP C210 /SK OVC027-TOP060 /TA M08 /TB LGT-MDT CHOP /IC LGT-MOD MX /RM IC PIREP Translated: SGF = Springfield, MO (nearest weather reporting station). /UA = Routine Pilot Report. /OV = Over the Springfield 040 degree radial at 20 Nautical miles. /TM = Time of pilot report is 1550 UTC. /FL = Flight Level / Altitude is 3,000 feet MSL (Essential information for icing and turbulence pilot reports). /TP = Type aircraft, C210 a Cessna 210 (Essential information for icing and turbulence pilot reports). /SK = Sky condition 2,700 feet overcast, top 6,000 feet MSL. /TA = Temperature minus eight ( 8 ) degrees Celsius. /TB = Turbulence light to moderate chop. /IC = Icing, light to moderate mixed (MX). /RM = Icing was encountered from 2,700 feet thru 6,000 feet MSL. A Typical Routine PIREP With Translation Current Conditions PIREPs Routine Pilot Reports = PIREPs (UA) Urgent Pilot Reports = PIREPs (UUA) Enter onto the weather brief form, any pertinent PIREPS affecting your route. PIREPS are issued as soon as reported. Reports actual in flight weather conditions. Distances are in nautical miles (NM). Times are UTC, Coordinated Universal Time. All altitudes MSL unless otherwise noted. Temperatures are reported in Celsius. Winds (WV) are referenced to TRUE North. Are There Any PIREPs Close to My Route? PIREPs are your best source of actual in flight weather conditions that verify forecasts and supplement the METARs by filling in the gaps between ground reporting stations. When reviewing pertinent PIREPs, pay particular attention to the Urgent PIREP (UUA). Urgent Pilot Reports are issued whenever any of the following phenomena occur: 1. Severe Icing (SEV). 2. Severe or extreme turbulence [(SEV / XTRM) (including clear air turbulence (CAT)]. 3. Low level wind shear (LLWS), with airspeed fluctuations of more than 10 knots. Low level wind shear (LLWS) is defined as wind shear with 2,000 feet of the surface. 4. Hail (GR = large hail / GS = small hail). 5. Tornadoes, funnel clouds, or waterspouts. 6. Any other weather phenomena an issuing FSS specialist considers hazardous to aircraft. 7. Volcanic ash clouds. PIREP Format: (Any element not reported will be omitted from the PIREP.) Station ID = Identifier of nearest weather reporting station to the reported weather event. Report Type = UA or UUA Routine or Urgent Pilot Report. Location = /OV Location of event over a navaid, weather reporting station, or a route. Time = /TM Time of Pilot Weather Report in Coordinated Universal Time (UTC). Altitude = /FL Altitude of aircraft and/or weather event (essential for ICG/TURB). Aircraft Type = /TP Type of aircraft is essential for icing and turbulence PIREPs. Sky Cover = /SK Cloud coverage bases / layers / tops. Weather = /WX Flight visibility and restrictions / precipitation / weather phenomena. Temperature = /TA Degrees Celsius, unless denoted as Fahrenheit. M = Minus. Wind (Vector) = /WV Direction in degrees of TRUE North, speed in KNOTS. Turbulence = /TB See page 30 for turbulence durations, intensities, and types. Icing = /IC See page 29 for icing durations, intensities, and types. Remarks = /RM For reporting elements not included, or to clarify previously reported elements. Low level wind shear (LLWS) reports for departing and landing aircraft are typically listed here. Details on the occurrence of icing, turbulence, cloud cover, etc. will be noted here if the weather event occurred at a different altitude than the altitude of the aircraft at the time of the pilot report. AWC = SKYSPOTTER PIREP. Compare Intensities: Note the type aircraft (TP) when evaluating PIREPs. A report of moderate turbulence for an airliner would translate to likely severe turbulence for a much smaller aircraft, such as a Cessna 152. The same holds true for icing, as well. Also, the age of a PIREP is an important consideration since weather can change rapidly. Older PIREPs may no longer offer accurate information. Make Pilot Reports: Help your fellow pilots with your pilot reports the best source of inflight turbulence and icing, and the only source of enroute weather conditions. Radio Flight Watch on or flight service on and make your pilot report. Learn how to evaluate inflight conditions with the AOPA SkySpotter training course at 37

42 Departure Airport Forecast Terminal Aerodrome Forecast (TAF) Enter onto the weather brief form the TAF data pertinent to your departure airport. Uses the same contractions as METARs. Covers a 5 statute mile radius of the airport. Forecast is good for a 24 hour time period. 32 high impact airports issue 30 hr TAFs. Scheduled TAFs are issued 4 times a day: Scheduled Issuance Valid Period Issuance Window 0000 UTC 0000 to 2400 UTC 2320 to 2340 UTC 0600 UTC 0600 to 0600 UTC 0520 to 0540 UTC 1200 UTC 1200 to 1200 UTC 1120 to 1140 UTC 1800 UTC 1800 to 1800 UTC 1720 to 1740 UTC What s the Forecast at My Departure Airport? When you review the TAF for your departure airport, keep in mind that forecasts are, at best, educated guesses. Compare the forecast with the current weather for the same time period. Does the current weather and the forecast agree? Is the weather better or worse than forecast? If worse, be suspicious of the forecast. Look at weather trends upwind from your departure airport. Are they better or worse than forecast? Look for amended TAFs. Forecasters seldom ever issue amendments for improving weather. Typically, only TAFs are amended where the weather is deteriorating faster or lower than expected. Examine the TAF for your departure airport for a time frame of at least one hour before to one hour after your departure. A two hour window either way would be even better. A newly issued TAF is more accurate for the near future than the previous older TAF where the later portion of the older TAF covers your takeoff. If your schedule permits, get the fresh TAF. You may notice, in some situations, where neighboring airports in close proximity to one another have very different TAFs. This may be due to a significant difference in airport elevation, or a local weather causer, such as a fog-prone river valley. Another explanation may be that the airports border separate National Weather Service Forecast Office areas of responsibility where different forecasters may issue dissimilar forecasts. If your departure airport does not issue a TAF, examine the Area Forecast for a general idea of what to expect. Keep in mind that Area Forecast cloud bases are forecast in MSL, unless otherwise stated as AGL or a ceiling (CIG). You must know the field elevation of your departure airport to estimate likely cloud bases at departure time. Also examine the nearby TAFs to compare their forecast cloud bases and visibilities with the Area Forecast. The neighboring TAFs can also provide a general idea of what surface winds to expect, if the surface flow is somewhat consistent in the grouping of surrounding TAFs. Comparing TAFs might not be all that helpful in the more remote areas of the country, however, where distances between TAF locations are too far apart to be representative. On the next page, you can explore some TAF terminology to develop an understanding of the Terminal Aerodrome Forecast. The destination airport discussion on pages 42 and 43 is essentially identical to this topic discussion. It is provided in both locations for your convenience in following the standard weather briefing format. A TAF TRAP! NSW: The contraction NSW is defined as No Significant Weather. This indicates that obstructions to visibility or precipitation previously noted in a TAF is expected to end. Pay special attention to the forecast cloud coverage and bases, which could actually be quite low so low, in fact, that safe VFR flight is not at all possible. Local Flights: If you are simply planning a local flight of a couple hours duration, it remains important to examine the forecast to prevent any weather surprises. As of Nov 5, 2008, 32 highimpact U.S. airports issue 30 hour TAFs. Valid date/time groups identify forecast data since 30 hour TAFs can carry over into a second day. All other TAFs remain valid for a 24 hour time period and contain date/time groups, too. 38

43 Departure Airport Forecast Terminal Aerodrome Forecast (TAF) Example TAF Decoded: TAF KOKC Z 15121/ KT 5SM BR BKN030 FM KT P6SM SKC BECMG G20KT 4SM SHRA OVC020 BECMG KT P6SM NSW SCT040 TAF = Terminal Aerodrome Forecast KOKC = Oklahoma City, OK Z = prepared on the fifteenth day at 1130 UTC 1512/1612 = valid from the fifteenth day at 1200 UTC until the sixteenth day at 1200 UTC 14008KT = wind from 140 degrees (true) at 8 knots 5SM = visibility 5 statute miles BR = mist BKN030 = ceiling 3,000 (feet AGL) broken FM = from 1600 UTC on the fifteenth day 16010KT = wind from 160 degrees (true) at 10 knots P6SM = visibility greater than 6 statute miles SKC = clear sky BECMG = becoming (a gradual change) 1522/1524 = between 2200 UTC & 2400 UTC on the fifteenth day 20013G20KT = wind from 200 degrees (true) at 13 knots gusting to 20 knots 4SM = visibility 4 statute miles SHRA = rain showers OVC020 = ceiling 2,000 (ft AGL) overcast BECMG = becoming (a gradual change) 1606/1608 = between 0600 UTC and 0800 UTC on the sixteenth day 21015KT = wind from 210 degrees (true) at 15 knots P6SM = visibility greater than 6 statute miles NSW = no significant weather SCT040 = 4,000 scattered TAF Terms: CB = cumulonimbus is the only cloud type used in TAFs. When CB is in a TAF it means thunderstorms. WS = windshear is used to forecast non-convective windshear up to 2,000 feet AGL. An example follows: WS020/18040KT Translation: Windshear up to 2,000 feet AGL, winds 180 degrees (true) at 40 knots at 2,000 feet AGL. PROB 30 = a slight chance, a 10% to 29% chance of a thunderstorm or form of precipitation occurring. PROB 40 = a chance, a 30% to less than 50% chance of a thunderstorm or form of precipitation occurring. FROM = after, used to forecast a rapid change in prevailing conditions, occurring in less than an hour. BECMG = becoming, used to forecast a gradual change in prevailing conditions occurring over a longer time period of usually two hours. TEMPO = occasional, used to describe forecast conditions which are expected to last for generally less than an hour. An example follows: TAF Sky Cover: Sky cover is forecast in eights of coverage (oktas). SKC Clear 0 oktas FEW Few 0 to 2 oktas SCT Scattered 3 to 4 oktas BKN Broken 5 to 7 oktas OVC Overcast 8 oktas The lowest level at which the cumulative cloud cover equals 5/8 or more is the forecast ceiling. VV009, BKN009, OVC009 for example, all indicate a 900 foot AGL ceiling. TEMPO 1519/1523 BKN030 Translation: Occasional ceilings 3,000 broken between 1900 UTC and 2300 UTC on the fifteenth day. VV = vertical visibility, used to forecast in hundreds of feet AGL the vertical visibility into a surface-based total obscuration, the ceiling. An example follows: BR VV006 Ceiling 600 feet AGL due to vertical visibility in mist. 39

44 Enroute Forecast Area Forecast (FA) Issued 3 Times a Day: Boston and Miami Chicago and Fort Worth San Francisco and UTC Issuance Time UTC Issuance Time Salt Lake City UTC Issuance Time 0845 DST 0945 DST 1045 DST 0945 STD 1045 STD 1145 STD 1745 DST 1845 DST 1945 DST 1845 STD 1945 STD 2045 STD 0045 DST 0145 DST 0245 DST 0145 STD 0245 STD 0345 STD Area Forecast Geographic Areas of Responsibility Each Area of Responsibility issues its own Area Forecast DST = Daylight Savings Time STD = Standard Time What s the General Weather Along My Route? Look for the states that involve your route of flight. Then look at the state breakdowns for the geographic segments associated with your route of flight. As you read the Area Forecast, remember that cloud bases are MSL unless denoted by AGL or CIG. In your preflight planning, make note of the field elevations of weather reporting and forecast stations along your route so you can compute the AGL cloud bases. This is especially important in mountainous terrain, where the forecast MSL cloud bases may at first glance indicate VFR conditions when, in actuality, VFR flight would not be possible due to lower AGL cloud bases. As with the AIRMETs, Area Forecasts are issued within the Areas of Responsibility noted on the map, above. Refer to the next page for an overview of the components of an FA. Area Forecasts are written in abbreviated plain language using FAA standard contractions. Each Area Forecast consists of a 12 hour forecast, plus a 6 hour categorical outlook. All times are in Coordinated Universal Time (UTC). Distances are in nautical miles. However, visibilities are specified in statute miles. Area Forecasts give MSL cloud tops information. See any Pilot Reports to confirm tops. General surface wind flow is also forecast on blustery days. Precipitation type and coverage are forecast, including thunderstorms. The forecast tops of thunderstorms gives an idea of their severity. Consider any CB tops above FL350 to be severe. The 6 hour categorical outlook, after the 12 th through the 18 th forecast hours use coding to describe the general ceiling and visibility conditions, which can be used for advanced planning purposes. The cause of the ceiling and/or visibility restriction is given, as well. LIFR (Low IFR) = Ceiling less than 500 feet and/or visibility less than 1 mile. IFR = Ceiling 500 to less than 1,000 feet and/or visibility 1 to less than 3 miles. MVFR (Marginal VFR) = Ceiling 1,000 to 3,000 feet and/or visibility 3 to 5 miles. VFR = Ceiling greater than 3,000 ft and visibility greater than 5 miles (includes sky clear). WND = If winds or gusts of 25 knots or greater are forecast, this code word is included. Using the TAFs: If you prefer using the TAFs as your enroute forecast tool, keep in mind that the TAF s forecast weather is within a localized area of the forecast station. TAFs may serve as a supplement to the Area Forecast, and in some cases may provide a more accurate appraisal of forecast weather. Using multiple resources can give contradicting forecast data. Trends of the observed weather may help determine which forecast is more valid. Cautions: Area Forecasts are general in nature, giving a Big Picture of VFR clouds and significant weather. You must always check AIRMET SIERRA for any IFR weather expected along your route of flight. As an Area Forecast ages, it s accuracy comes into question, especially on those days with changeable weather patterns. Cloud bases are always MSL, unless AGL or CIG are noted. 40

45 Enroute Forecast Area Forecast (FA) Anatomy of an Area Forecast: Remember IFR conditions are extracted from AIRMET Sierra 18 hour synopsis 12 hour forecast plus a 6 hour outlook Be sure to read the AIRMETS! 3 AIRMETs Sierra are in effect at the beginning valid time of this Area Forecast. It would be easy to draw the conclusion that no IFR conditions are forecast by examining only the Area Forecast. Always remember that the Area Forecast discusses VFR CLOUDS AND WEATHER ONLY! Coverage of Thunderstorms (if forecast): ISOL (isolated) = single cells no percentage WDLY SCT (widely scattered) = less than 25% SCT or AREAS (scattered or areas) = 25% to 54% NMRS (numerous) = 55% or more WDSPRD (widespread) = 55% or more Always compare field elevation of airports with MSL cloud bases to estimate AGL cloud bases. Bases are always MSL unless AGL or CIG is stated. This is the Significant Clouds and Weather section of the Area Forecast. States and/or groupings of states, and portions of states are discussed together where the forecast weather is similar in content. See Appendix J for a map of terrain features and geographical areas typically mentioned in the Area Forecast and other NWS weather discussions. TOPS are always referenced to MSL NOT height above ground level. 41

46 Destination Forecast Terminal Aerodrome Forecast (TAF) Enter onto the weather brief form the TAF data pertinent to your flight s destination. Uses the same contractions as METARs. Covers a 5 statute mile radius of the airport. Forecast is good for a 24 hour time period. 32 high impact airports have 30 hr TAFs. Scheduled TAFs are issued 4 times a day: Scheduled Issuance Valid Period Issuance Window 0000 UTC 0000 to 2400 UTC 2320 to 2340 UTC 0600 UTC 0600 to 0600 UTC 0520 to 0540 UTC 1200 UTC 1200 to 1200 UTC 1120 to 1140 UTC 1800 UTC 1800 to 1800 UTC 1720 to 1740 UTC What s the Forecast at My Destination Airport? When you review the TAF for your destination airport, keep in mind that forecasts are, at best, educated guesses. Compare the forecast with the current weather for the same time period. Does the current weather and the forecast agree? Is the weather better or worse than forecast? If worse, be suspicious of the forecast. Look at weather trends upwind from your destination airport. Are they better or worse than forecast? Look for amended TAFs. Forecasters seldom ever issue amendments for improving weather. Typically, only TAFs are amended where the weather is deteriorating faster or lower than expected. Examine the TAF for your destination airport for a time frame of at least one hour before to one hour after your ETA. A two hour window either way would be even better. A newly issued TAF is more accurate for the near future than the previous older TAF where the later portion of the older TAF covers your ETA. If your schedule permits, get the fresh TAF, if you can t get it before departing, definitely request it while enroute. You may notice, in some situations, where neighboring airports in close proximity to one another have very different TAFs. This may be due to a significant difference in airport elevation, or a local weather causer, such as a fog-prone river valley. Another explanation may be that the airports border separate National Weather Service Forecast Office areas of responsibility where different forecasters may issue dissimilar forecasts. If your destination airport does not issue a TAF, examine the Area Forecast for a general idea of what to expect. Keep in mind that Area Forecast cloud bases are forecast in MSL, unless otherwise stated as AGL or a ceiling (CIG). You must know the field elevation of your destination airport to estimate likely cloud bases upon arrival. Also examine the nearby TAFs to compare their forecast cloud bases and visibilities with the Area Forecast. The neighboring TAFs can also provide a general idea of what surface winds to expect, if the surface flow is somewhat consistent in the grouping of surrounding TAFs. Comparing TAFs might not be all that helpful in the more remote areas of the country, however, where distances between TAF locations are too far apart to be representative. One final consideration If flying under Instrument Flight Rules, are you going to need an alternate airport? If you do, don t forget to check NOTAMs for your alternate, too. On the next page, you can explore some TAF terminology to develop an understanding of the Terminal Aerodrome Forecast. A TAF TRAP! NSW: The contraction NSW is defined as No Significant Weather. This indicates that obstructions to visibility or precipitation previously noted in a TAF is expected to end. Pay special attention to the forecast cloud coverage and bases, which could actually be quite low so low, in fact, that safe VFR flight is not at all possible. See Appendix E for maps and a decoder of TAF locations in the U.S. As of Nov 5, 2008, 32 highimpact U.S. airports issue 30 hour TAFs. Valid date/time groups identify forecast data since 30 hour TAFs can carry over into a second day. All other TAFs remain valid for a 24 hour time period and contain date/time groups, too. 42

47 Destination Forecast Terminal Aerodrome Forecast (TAF) Example TAF Decoded: TAF Terms: TAF KOKC Z 1512/ KT 5SM BR BKN030 FM KT P6SM SKC BECMG G20KT 4SM SHRA OVC020 BECMG KT P6SM NSW SCT040 TAF = Terminal Aerodrome Forecast KOKC = Oklahoma City, OK Z = prepared on the fifteenth at 1130 UTC 1512/1612 = valid from the fifteenth at 1200 UTC until the sixteenth at 1200 UTC 14008KT = wind from 140 degrees (true) at 8 knots 5SM = visibility 5 statute miles BR = mist BKN030 = ceiling 3,000 (feet AGL) broken FM = from 1600 UTC on the fifteenth day 16010KT = wind from 160 degrees (true) at 10 knots P6SM = visibility greater than 6 statute miles SKC = clear sky BECMG = becoming (a gradual change) 1522/1524 = between 2200 UTC and 2400 UTC on the fifteenth day 20013G20KT = wind from 200 degrees (true) at 13 knots gusting to 20 knots 4SM = visibility 4 statute miles SHRA = rain showers OVC020 = ceiling 2,000 (ft AGL) overcast BECMG = becoming (a gradual change) 1606/1608 = between 0600 UTC and 0800 UTC on the sixteenth day 21015KT = wind from 210 degrees (true) at 15 knots P6SM = visibility greater than 6 statute miles NSW = no significant weather SCT040 = 4,000 scattered TAF Sky Cover: Sky cover is forecast in eights of coverage (oktas). SKC Clear 0 oktas FEW Few 0 to 2 oktas SCT Scattered 3 to 4 oktas BKN Broken 5 to 7 oktas OVC Overcast 8 oktas The lowest level at which the cumulative cloud cover equals 5/8 or more is the forecast ceiling. VV009, BKN009, OVC009 for example, all indicate a 900 foot AGL ceiling. CB = cumulonimbus is the only cloud type used in TAFs. When CB is in a TAF it means thunderstorms. WS = windshear is used to forecast non-convective windshear up to 2,000 feet AGL. An example follows: WS020/18040KT Translation: Windshear up to 2,000 feet AGL, winds 180 degrees (true) at 40 knots at 2,000 feet AGL. PROB 30 = a slight chance, a 10% to 29% chance of a thunderstorm or form of precipitation occurring. PROB 40 = a chance, a 30% to less than 50% chance of a thunderstorm or form of precipitation occurring. FROM = after, used to forecast a rapid change in prevailing conditions, occurring in less than an hour. BECMG = becoming, used to forecast a gradual change in prevailing conditions occurring over a longer time period of usually two hours. TEMPO = occasional, used to describe forecast conditions which are expected to last for generally less than an hour. An example follows: TEMPO 1519/1523 BKN030 Translation: Occasional ceilings 3,000 broken between 1900 UTC and 2300 UTC on the fifteenth day. VV = vertical visibility, used to forecast in hundreds of feet AGL the vertical visibility into a surface-based total obscuration, the ceiling. An example follows: BR VV006 Ceiling 600 feet AGL due to vertical visibility in mist. 43

48 U.S. Government Image Winds Aloft Forecast (FB) Enter onto the weather brief form the winds aloft data pertinent to your flight route. Issued four (4) times daily, by computer. Winds and temperatures are FORECAST. Wind direction is from TRUE North. 2 digit wind speed is in KNOTS. 2 digit altitudes up to 12,000 feet are MSL. 2 digit temps above FL24,000 are negative. FL18,000 and above are pressure altitudes. Winds Aloft Graphic Display Map What Are the Winds Aloft for My Flight Altitudes? More Key Points: Record the winds aloft for all of the possible altitudes you may fly along your route of flight. If your selected altitude is between the altitudes listed in the winds aloft, you can interpolate the speed and direction. If your route of flight takes you between forecast stations, interpolate these winds, as well. Temperatures up through 24,000 feet preceded with a plus sign indicate positive temperatures. A minus sign indicates negative temps. Winds and Temperatures Aloft Forecasts (FB) are computer generated forecasts of wind direction, wind speed, and temperature at specified times, locations, and altitudes. Temperature is omitted for the first 3,000 foot level. The Winds Aloft header includes: (1) the date and times upper level wind observations were collected (Data Based On), (2) the forecast (Valid) date and time, and (3) the time period during which the Forecast Winds and Temperatures Aloft are to be used (For Use): Light & variable wind speeds of less than five (5) knots are indicated by (1) (3) Winds aloft are not forecast for altitudes within 1,500 feet of a station s elevation. (2) Graphic Winds Aloft: The Winds and Temperatures Aloft Forecast Periods are listed in the chart below. The farther out in the forecast period for the winds aloft, the less accurate they are likely to be. In other words, the 6 hour wind set is more reliable than the 24 hour wind set. Aviation Digital Data Service (ADDS) offers charts of the winds aloft in three formats: Wind speed & direction with wind barbs. Wind streamlines with arrows indicating wind flow. Color coded temperature map. U.S. Government Image Computing Winds in Excess of 99 Knots: Forecast winds from 100 to 199 knots are converted by subtracting 50 and adding 100: Example: : 73 minus 50 = 230 degrees, 19 plus 100 = 190 knots, temp minus 60C. Winds 200 knots or greater are indicated with a forecast speed of 199 knots: Example: : 77 minus 50 = 270 degrees at 199 (plus) knots, temperature minus 55 C. These charts are an unofficial supplement and are not to be used as a substitute of the official textual data, the FB. 44

49 Notices To Airmen (Notams) A NOTAM describes an abnormal condition, such as an equipment outage or limitation. A NOTAM also alerts pilots that a potentially dangerous condition exists, such as a snow covered runway or active Restricted Area. Always check NOTAMs immediately prior to takeoff for any changes in status of any National Airspace components you will use, as well as airspace hazards or restrictions. Are There Any NOTAMs Pertinent to My Flight? In your search for current NOTAMs, you will be examining the Distant NOTAMs (NOTAMs D ), the FDC NOTAMs, and if you have access to it, the Notices to Airmen Publication (Class II), or NTAP. An electronic version of this publication is published every 28 days. It is an essential resource in your NOTAM search. It can be accessed at: D NOTAMs pertain to critical information available over a telecommunications network, such as navaids, airports, and airspace, etc., which is not received in sufficient time to be published in the NTAP. FDC NOTAMs are regulatory, covering TFRs or instrument approach procedures, etc. They are initially available over the NOTAMs network then, later, published in the NTAP. The NTAP contains NOTAMs concerning airway changes, special events, and many other National Airspace System changes received in time to be published in book form. Effective January 28, 2008, Local NOTAMs (NOTAMs L) were changed to NOTAMs D. Also introduced were a number of keywords, now placed prior to the NOTAM text which, in essence, does not make it any more difficult to interpret NOTAMs. It simply gives a better idea of what the NOTAM pertains to. All NOTAMs D text includes the keywords: RWY = Runway, TWY = Taxiway, RAMP = Ramp, APRON = Apron, AD = Aerodrome, OBST = Obstruction, NAV = Navigation Aids, COM = Communications, SVC = Services, AIRSPACE = Airspace, U = Unverified Aeronautical Information, O = Other Aeronautical Information. Although there is no formal timeline, during a transitional period of approximately four months, previously issued NOTAMs will be converted to the new formats as time permits. DUAT and DUATS are the only FAA approved personal computer accessed on-line weather briefing services where you can retrieve the NOTAM database. Calling flight service is your only other reliable alternative, but even then, their NOTAM database may not be up to date. But, at least, you will have it on record that you specifically requested NOTAMs, should an incident occur. Another alternative is to telephone airport management for current NOTAMs or other limitations or unusual circumstances. This might work well for the smaller airports, but larger airport managers most likely would not have the time or inclination to help you. TIPS: If your destination airport has multiple runways that are closed by NOTAM, be sure to check out the airport diagram. All runways could be closed. Take a minute to call Unicom at non-towered airports for the latest airport information, even though this radio call is not required. If able, a radio call to flight service close to destination can give updates. Most Critical NOTAMs: Aerobatic Areas Airport Closures Air Shows Approach Lighting Systems Approach Navaids ATC Tower Outages Braking Action Reports Cranes in Airport Vicinity Demonstration Aircraft Laser Light Operations Parachute Jumping Restricted Areas Temporary Flight Restrictions Unmanned Rocket Launches 45

50 Notices To Airmen (Notams) A Typical NOTAM D Decoded (ABC and XYZ are example 3-letter identifiers) Selected Sample NOTAM Text Examples: (accountability data and year/month/date/time excluded) ABC 07/003 XYZ NAV VOR OTS TIL Translated: The XYZ VOR is out of service until 2000 UTC on July 16, ABC = used by the NOTAM system for accountability. 07/003= 07 is the month (JULY) / 003 = the 3 rd NOTAM issued for ABC accountability location in July. XYZ = the affected location the identifier of a naviad, airport, etc. start reading the NOTAM here. NAV = the NOTAM keyword, indicating a navaid. VOR = the type of affected facility. OTS = the condition of the affected facility. TIL = the timeframe of the facility s abnormal status = the year/month/day/hours/minutes UTC: 08 = 2008 / 07 = July / 16 = 16 th day / 2000 = 2000 UTC AIRSPACE PJE 3 NMR HZL 8000/BLW WEF Parachute jump exercise within a 3 nautical mile radius of the Hazelton VOR, 8,000 feet MSL and below. AIRSPACE UNMANNED ROCKET 3NMR HAR FL250/BLW WEF Unmanned (model) rocket launch within a 3 nautical mile radius of the Harrisburg Vortac. The rocket(s) will climb as high as Flight Level 250. Selected NOTAM Terms Briefly Defined: TIL = until WEF = effective from / with effect from WIE = with immediate effect (used in FDC NOTAMs) NA = not authorized (does not mean not applicable ) PJE = parachute jump exercise (parachute jumps) RTS = return to service UNMNT = unmonitored (associated with navaids) UNUSBL = unusable (for IFR flight usage associated with navaids which may continue to emit a signal, but the signal is not reliable). UNREL = unreliable ASR = antenna structure registration PLUS SEE = typically followed by AFD. NOTAMs with PLUS SEE AFD indicate that you must consult the Airport/Facility Directory to determine what published limitation or abnormality limits the affected facility. SEE = The word SEE in a NOTAM is directing you to another NOTAM associated with a TFR or an ATC delay. SEE is used in pointer NOTAMS. BA FAIR = braking action fair (slippery runway) BA POOR = braking action poor (very slippery runway) BA NIL = braking action nil (extremely slippery runway) AIRSPACE AEROBATIC ACFT 4500/BLW 5 NMR DUJ AVOIDANCE ADZD WEF Aerobatic aircraft operating at an altitude of 4,500 feet MSL and below within a 5 nautical mile radius of the Dubois Airport. MIV AD CLSD EXC SKED ACR/AIRSHOW ACFT 8000/BLW 5 NMR MIV AVOIDANCE ADZD Millville airport closed except to scheduled air carriers and air show aircraft, 8,000 feet MSL and below within a 5 nautical mile radius of the Millville Airport. CLW OBST CRANE 195 (125 AGL).25 NE (2755N08241W) TIL Clearwater Air Park has an obstruction, a crane, 195 feet MSL in height, 125 feet AGL, located ¼ statute mile northeast of the airport (Latitude/Longitude coordinates). 46

51 A Partial Example of a Presidential TFR in FDC NOTAM Format:!FDC 7/7886 ZKC PART 1 OF 3 FLIGHT RESTRICTION SAINT LOUIS, MISSOURI, AUGUST 26, 2007 LOCAL PURSUANT TO TITLE 14 SECTION OF THE CODE OF FEDERAL REGULATIONS AIRCRAFT FLIGHT OPERATIONS ARE PROHIBITED WITHIN 30 NMR UP TO BUT NOT INCLUDING FL180 OF... This FDC NOTAM references: SECTION This is a Presidential TFR Typical size is a 30 nautical mile radius up to FL180 That s a 60 nautical mile diameter! This is the Big One Do not violate this TFR! Temporary Flight Restrictions and Special Use Airspace Consider a TFR to be a NO FLY ZONE. A Temporary Flight Restriction: Is NOT DEPICTED on aeronautical charts. Is usually SHORT TERM in duration. Can appear, disappear, or change daily. TFRs are issued by FDC NOTAM, explaining: Where the TFR is located. How big it is, usually in terms of a radius. How high it extends in altitude. How long it is expected to remain in effect. Are There Any TFRs Along My Route of Flight? Retrieving current TFR information through self briefing can be an easy task. A number of resources are available for viewing TFR information. However, one admonition remains: The FAA disclaimer: Pilots should call a Flight Service Station at WX-BRIEF ( ) for the latest TFR information. A few of the better resources for viewing TFR information (other than DUAT/S) include: This is the official FAA TFR web site, listing TFRs by type, state, and ARTCC in table format. Very detailed and easy to use. The AOPA posts new TFR information on this web page as soon as possible after it is issued by the FAA. Offers graphic depictions. Offers free TFR data plus other enhanced for-fee services. TIP: Get the sports schedule for professional and collegiate NCAA Division One sports events in your local flying area. Anticipate TFRs over the sports stadiums of these football and baseball games and also over motor sports speedways when scheduled. Avoid these areas by at least a 3 nautical mile radius and stay above an altitude of at least 3,000 feet AGL, unless otherwise authorized by ATC. AOPA offers an excellent resource for viewing Special Use Airspace activity: Offers a wonderfully depicted chart of Special Use Airspace concerning the active or inactive status of restricted areas, military operations areas, military routes, or warning areas. AOPA membership is required. As far as the Military Training Routes (MTRs) depicted on the charts are concerned, keep one thought in mind: The pilots using MTRs might be off course and off schedule. Always have your head on a swivel when flying in the vicinity of the MTR routes. No matter how carefully you check for TFRs, checking NOTAMs multiple times before you take off, you can still be caught by a last minute pop-up TFR along your route. For those of you making extended flights from the New England and Mid-Atlantic areas to points south, and vice-versa, finding a place to refuel or to safely navigate can be quite a challenge due to your proximity to the Washington D.C. SFRA. Know its procedures well. TFRs May Issued For: Presidential Movements Forest Fires Disaster or Hazard Areas Significant Aircraft Accidents Space Flight Operations Space Shuttle Launches Major Sporting Events Major Aerial Demonstrations Hijackings Special Security Situations: Disneyland & Disneyworld National Landmarks Military Installations Over Major Cities The good news is that if you commit an inadvertent incursion of a security TFR, you will not be subject to criminal prosecution unless it is due to knowing or willful conduct. 47

52 U.S. Government Image Air Traffic Control (ATC) Delays Information Availability - Continuous at: Information Available: General airport delay information Is NOT flight specific An Interactive map is available at : General Arrival/Departure Delays Taxi Delays Airborne Holding Delays Departure Airport Delays Closed Airports Air Traffic Control System Command Center This web site is most beneficial to the pilots who regularly fly in and out of select major air carrier airports located throughout the United States. (see sidebar to the right for the airport identifiers) This incredible web site offers many valuable resources, such as: Advisories Database: Airspace Flow Program, Ground Stops, Ground Delay Programs. EDCT Lookup: Allows Individual aircraft operators to determine if an EDCT has been issued for their specific flight. Operational Information System: Real-time airport delay information as received from FAA facilities. Special Traffic Management Program (estmp): Pilots using the Internet can make arrival & departure reservations at airports participating in special management events. e-cvrs Reservation web based application for reservations into the high-density traffic airports (HDTA) of ORD, DCA, JFK, LGA. Aviation Information System: The operating status of the nation s largest airports delivered to the wireless device of your choice (see TIP sidebar). And Other Valuable Features Visit the ATSCC web side for details. ATL IAD ORD BNA IAH PDX BOS IND PHL BWI JFK PIT CLE LAS RDU CLT LAX SEA CVG LGA SFO DCA MCI SJC DEN MCO SLC DFW MDW STL DTW MEM TEB EWR MIA TPA FLL MSP TIP: You can receive operating status information of the nation s largest airports delivered to your wireless device, pager, PDA, or e mail in real time through the Aviation Information System. Find all of the details on the ATSCC web site at the url: flyfaa/usmap.jsp 48

53 So, Can You Go As Planned? Should I: Go VFR or IFR? Depart as scheduled? Delay departure or go sooner? Alter my route? Select a different altitude? Wait until another day? Is my aircraft equipped to handle the weather conditions along my route? Are my experience and proficiency sufficient for my planned trip? I ve Got My Weather It s Decision Time! If instrument rated, will you file an instrument flight plan? Are the IMC conditions within your capabilities? Can you postpone your flight, or go sooner? Is an alternate flight route a better choice? Are you fully qualified, current, and proficient for hard IFR, if need be? If you are VFR rated only, do you feel confident that you can safely complete your flight in marginal weather based on what you ve reviewed? Take one last look at the newest METARs and check for updated TAFs one last time. What s the trend? Up or down? When making your flight decision in evaluating any marginal weather, keep in mind that conditions between weather reporting stations may be lower than reported at the stations available for review. You may encounter areas of reduced ceilings and visibilities because weather is seldom uniform even over short distances. This is especially true in remote locations with longer distances and differences in elevation between reporting stations. Also be aware that forecasts may be quite inaccurate. Take the time to compare current weather trends with forecast data to determine the validity of the forecast. Are reported weather conditions lower than forecast for that time period? If they are, and you are VFR rated only, consider canceling your flight. If you are an experienced pilot and decide weather conditions meet your personal and FAA limitations, always determine where better weather is located in relation to your proposed route, if you need an escape route due to equipment failure or lower than expected weather. Plan your route, choosing en route airports you can divert to, if needed. If VFR, fly under an overcast so you don t get trapped on top. If conditions deteriorate, turn around or land at the earliest safe opportunity. If you are flying IFR, don t just examine the Low Altitude Enroute Charts. Take a look at the appropriate Sectionals to have an appreciation for the terrain beneath you, if in IMC. NOTAMs are a consideration in your go-no-go decision, as well, if a critical airspace or airport component is unavailable. Be sure to specifically check the components you ll use. If you do not understand any aspect of the weather information you have reviewed, call flight service for clarification or an explanation before you go. And when you do go, help out your fellow pilots make some pilot reports. Share With Your Passengers: Let your passengers know what to expect. Tell them your personal minimums so they will understand if you decide to alter your flight. Got a Question? The AOPA Pilot Information Center, available to AOPA members, can give answers to any general aviation topic at , or at: pilotassist@aopa.org Your Job s Not Done Yet! After takeoff, you must make a constant appraisal of the weather conditions ahead on your route of flight. If you do not have the luxury of any of the commercial services such as XM Satellite Weather or datalink, or onboard weather surveillance radar, you can always call Flight Watch on or flight service on for continuous updates. 49

54 Filing Flight Plans DUAT & DUATS plus other commercial vendors offer flight planning and filing by computer. If filing verbally with AFSS, give data in proper order. Filing a domestic VFR flight plan is not a requirement. However, it is always a good operating practice as an insurance policy. The filing of flight plans is required in two circumstances: (1) To fly by instrument flight rules. (2) VFR flights in coastal and domestic air defense zones (ADIZ), including the ADIZ around Washington, D.C. You should already know how to file a flight plan from your flight training or experience. Some reminders and tips are included here. All Flight Plans: Flight Plan Filing Tips: Use Universal Coordinated Time (UTC) for proposal times and the phonetic location identifiers for airports, fixes, and intersections when filing flight plans with flight service to prevent misunderstanding. A distant flight service station may take your call where a same-named airport will have a different identifier, ie: BFD = Bradford, Pennsylvania and BDF = Bradford, Illinois! VFR Flight Plans (Never forget to CLOSE YOUR VFR FLIGHT PLAN!): After a VFR flight plan is filed, it must be activated upon departure, whereupon flight service knows where and when you are expected to arrive. If you do not arrive within one half hour after your ETA, an aircraft search will begin. Update your ETA, if running late. Entering a remark such as, Request VFR Flight Following is pointless since only flight service processes your flight plan. If you want VFR flight following, you must establish radio contact with the appropriate ATC facility and verbally request this service. IFR Flight Plans: File no more than 22 hours in advance nor less than one-half hour before your proposed departure time to prevent any delay in receiving your clearance. If filing DIRECT when traversing multiple ARTCC airspace, file the lat/long of one fix on your route contained in the adjacent ARTCC from your departure ARTCC. Place in remarks, L/L= (fix name) (otherwise the FAA computer may reject your flight plan). When filing, place departure procedures and/or standard arrivals in the remarks section to prevent your flight plan from possibly being rejected by the FAA computer. If you want your clearance given to you as you filed it, as opposed to being issued, Cleared as filed, place FRC in remarks (FRC stands for Full Route Clearance ). If filing an instrument flight plan with the departure point and the destination being the same airport, you must place at least one fix in the route of flight. Otherwise, the flight plan will be rejected by the FAA computer. If filing airways and fixes to a destination airport with the final fix co-located on the airport, the final fix in the route of flight must be the navaid connected to the final airway. Then place the destination airport in the destination field. Contact Phone No. VFR Flight Plan: When filing VFR flight plans always give a contact phone number where flight service can reach you or a trusted representative immediately. Do not use a phone number that will connect to voic or an answering machine. If you become overdue or if you forget to close your flight plan, action must be taken immediately to locate your aircraft. Cell phones are best. IFR Flight Plan Delayed Departure: If your proposed departure time for an IFR flight plan is delayed one hour or more, update your new proposed departure time to ensure your flight plan will remain active in the FAA computer flight plan data base. If you do not update your proposal time, the FAA computer will delete your flight plan from its data base. 50

55 AFSS Tips and Information The national system of Lockheed Martin flight service is comprised of a network of 3 Hub stations plus auxiliary stations located throughout the United States. When telephoning, depending on workload, your call may be routed to any HUB within the network, or to your local auxiliary station. Lockheed Martin s AFSS Pilot Information Portal web site is designed to help you to better understand the services they offer. Visit for information. The Alaska network of flight service stations remains under the ownership of the FAA. How To Get More Out of Flight Service There may be times when you must, or you elect to call Lockheed Martin flight service. To improve the quality of your experience with flight service, follow these guidelines: Always, always, always use Universal Coordinated Time (UTC) when expressing times and the phonetic location identifiers for airports, fixes, and intersections when discussing locations or filing flight plans with flight service to prevent misunderstanding. Any of the flight service stations in the U.S. may take your call when their telephone call rate is high. Example: A distant flight service station may take your call where a same-named airport will have a different identifier, ie: PWM = Portland, Maine and PDX = Portland, Oregon! The same as above especially holds true for IFR clearance requests. Misunderstandings concerning same-named airports in different states can lead to tragic consequences, if the air traffic controller issues a clearance such as Cleared as filed. So, again, always use the phonetically spelled airport identifiers when requesting clearance to prevent errors. If contacting flight service by air to ground radio, establish initial contact with your full call sign, your location, and the frequency you are listening over. Do not transmit your message or make your request until radio contact is established. Flight service monitors MANY frequencies, working multiple aircraft on other frequencies during your radio call. It is strongly recommended that you visit to fully understand the flight service system. There are numerous articles and tips on how to make effective use of the system to improve your flight service experience. Under the link Contact Us, you will find a national map pinpointing the locations of the existing flight service stations along with contact information if you wish to discuss an issue with the facility manager. A feedback link is also available if you wish to compliment, complain, or discuss an issue by . If you are an aviation history buff, an FSS history link is available, also. The AOPA web site, has a printable AFSS TIPS card in PDF format that provides quick reference information which is an invaluable tool for accessing flight service products and services. It is an indispensable aid demonstrating how to use the shortcuts of the telephone answering system, how to obtain a clearance, and what numbers to dial for international customs notifications. To access the tips card, type AFSS TIPS in the web site search window in the upper right corner, click on GO, and then click on ATTENTION to the right of [pdf] on the search result, AFSS TIPS. Call This is the initial number to access the system for a pilot weather briefing. From this number, you can respond to prompts to: Speak to a briefer Listen to a TIBS Record Fast File Flight Plans Hear Special Announcements Additional phone numbers are available for international needs or clearance delivery. See for details. Got a Complaint? Don t grumble and keep it to yourself. Express yourself to improve service by calling the FAA at AOPA and Lockheed Martin want to know about the problems you encounter. They are sincere in wishing to improve service for you. They need your feedback if the system is to be improved. A representative may contact you to discuss your concerns. 51

56 Appendix A Weather Brief Master Copy Page Your Background Information: Aircraft Identification: Type Aircraft: Type of Flight: IFR VFR SVFR ADIZ Departure Point: Estimated Departure Time: Synopsis: Enroute Altitude: Route of Flight: Destination: Estimated Time Enroute: Alternate Airport: Departure Airport Forecast: Adverse Conditions: Enroute Forecast: Freezing Level: Departure: Enroute: Destination: Destination Forecast: Current Conditions: Departure Airport: Enroute: Winds Aloft: NOTAMs / TFRs / MTRs / ATC Delays: Destination: PIREPS: Alternate Airport Current / Forecast / NOTAMs: A-1

57 Appendix A Enlarged Weather Brief Master Copy Adverse Conditions: A-2

58 Appendix B National State Identifier Map State Contractions Decoder AK Alaska AL Alabama AR Arkansas AZ Arizona CA California CO Colorado CT Connecticut DC District of Columbia DE Delaware FL Florida GA Georgia IA Iowa ID Idaho IL Illinois IN Indiana KS Kansas KY Kentucky LA Louisiana MA Massachusetts MD Maryland ME Maine MI Michigan MN Minnesota MO Missouri MS Mississippi MT Montana NC North Carolina ND North Dakota NE Nebraska NH New Hampshire NJ New Jersey NM New Mexico NV Nevada NY New York OH Ohio OK Oklahoma OR Oregon PA Pennsylvania RI Rhode Island SC South Carolina SD South Dakota TN Tennessee TX Texas UT Utah VA Virginia VT Vermont WA Washington WI Wisconsin WV West Virginia WY Wyoming B-1

59 Appendix C WA WS WST National Plotting Map C-1

60 Appendix C WA WS WST Plotting Map Decoder ABI - Abilene, TX ABQ - Albuquerque, NM ABR - Aberdeen, SD ABY Albany, GA ACK - Nantucket, MA ACT - Waco, TX ADM - Ardmore, OK AEX - Alexandria, LA AIR - Bellaire, OH AKO - Akron, CO ALB - Albany, NY ALS - Alamosa, CO AMA - Amarillo, TX ANW - Ainsworth, NE APE - Appleton, OH ARG - Walnut Ridge, AR ASP - Oscoda, MI ATL - Atlanta, GA AUS - Austin, TX BAE - Milwaukee, WI BAM - Battle Mntn, NV BCE - Bryce Canyon, UT BDF - Bradford, IL BDL - Windsor Locks, CT BFF - Scottsbluff, NE BGR - Bangor, ME BIL - Billings, MT BIS - Bismark, ND BJI - Bemidji, MN BKE - Baker, OR BKW - Beckley, WV BLI - Bellingham, WA BNA - Nashville, TN BOI - Boise, ID BOS - Boston, MA BOY - Boysen Resv., WY BPI - Big Piney, WY BRD - Brainerd, MN BRO - Brownsville, TX BTR - Baton Rouge, LA BTY - Beatty, NV BUF - Buffalo, NY BUM - Butler, MO BVL - Bonneville, UT BVT - Lafayette, IN BWG Bowling Green, KY BZA - Yuma, AZ CAE - Columbia, SC CDS - Childress, TX CEW - Crestview, FL CHE - Hayden, CO CHS - Charleston, SC CIM - Cimarron, NM CLE - Cleveland, OH CLT - Charlotte, NC CON - Concord, NH COU - Columbia, MO CRG - Jacksonville, FL CRP - Corpus Christi, TX CSN - Casanova, VA CTY - Cross City, FL CVG - Covington, KY CYN - Coyle, NJ CYS - Cheyenne, WY CZI - Crazy Woman, WY CZQ - Fresno, CA DBL - Eagle, CO DBQ - Dubuque, IA DBS - Dubois, ID DCA - Washington, DC DDY - Casper, WY DEC - Decatur, IL DEN - Denver, CO DFW Dallas Ft Worth, TX DIK - Dickinsin, ND DLF - Laughlin AFB, TX DLH - Duluth, MN DLL - Dells, WI DLN - Dillon, MT DMN - Deming, NM DNJ - Mc Call, ID DPR - Dupree, SD DRK - Prescott, AZ DSD - Redmond, OR DSM - Des Moines, IA DTA - Delta, UT DVC - Dove Creek, CO DXO - Detroit, MI DYR - Dyersburg, TN EAU - Eau Claire, WI ECG - Elizabeth City, NC ECK - Peck, MI EED - Needles, CA EHF - Bakersfield, CA EIC - Shreveport, LA EKN - Elkins, WV ELD - El Dorado, AR ELP - El Paso, TX ELY - Ely, NV EMI - Westminster, MD END - Vance AFB, OK ENE - Kennebunk, ME ENI - Ukiah, CA EPH - Ephrata, WA ERI - Erie, PA ETX - East Texas, PA EUG - Eugene, OR EWC - Ellwood City, PA EYW - Key West, FL FAM - Farmington, MO FAR - Fargo, ND FCA - Kalispell, MT FLO - Florence, SC FMG - Reno, NV FMN - Farmington, NM FMY - Ft Myers, FL FNT - Flint, MI FOD - Ft Dodge, IA FOT - Fortuna, CA FSD - Sioux Falls, SD FSM - Ft Smith, AR FST - Ft Stockton, TX FWA - Ft Wayne, IN GAG - Gage, OK GCK - Garden City, KS GEG - Spokane, WA GFK - Grand Forks, ND GGG - Longview, TX GGW - Glasgow, MT C-2

61 Appendix C WA WS WST Plotting Map Decoder GIJ Niles (Gipper), MI GLD - Goodland, KS GQO - Chattanooga, TN GRB - Green Bay, WI GRR - Grand Rapids, MI GSO - Greensboro, NC GTF - Great Falls, MT HAR - Harrisburg, PA HBU - Gunnison, CO HEC - Hector, CA HLC - Hill City, KS HLN - Helena, MT HMV - Holston Mntn, TN HNK - Hancock, NY HNN - Henderson, WV HQM - Hoquiam, WA HTO - East Hampton, NY HUL - Houlton, ME HVE - Hanksville, UT HVR - Havre, MT IAH - Houston Intl, TX ICT - Wichita, KS IGB - Bigbee, MS ILC - Wilson Creek, NV ILM - Wilmington, NC IND - Indianapolis, IN INK - Wink, TX INL - Intl Falls, MN INW - Winslow, AZ IOW - Iowa City, IA IRK - Kirksville, MO IRQ - Colliers, SC ISN - Williston, ND JAC - Jackson, WY JAN - Jackson, MS JCT - Junction, TX JFK - New York/JFK, NY JHW - Jamestown, NY JNC - Grand Junction, CO JOT - Joliet, IL JST - Johnstown, PA LAA - Lamar, CO LAR Laramie, WY LAS - Las Vegas, NV LAX - Los Angeles, CA LBB - Lubbock Intl, TX LBF - North Platte, NE LBL - Liberal, KS LCH - Lake Charles, LA LEV - Grand Isle, LA LFK - Lufkin, TX LGC - La Grange, GA LIT - Little Rock, AR LKT - Salmon, ID LKV - Lakeview, OR LOU - Louisville, KY LOZ - London, KY LRD - Laredo, TX LVS - Las Vegas, NM LWT - Lewistown, MT LYH - Lynchburg, VA MAF - Midland, TX MBS - Saginaw, MI MCB - Mc Comb, MS MCK - Mc Cook, NE MCN - Macon, GA MCW - Mason City, IA MEI - Meridian, MS MEM - Memphis, TN MGM - Montgomery, AL MIA - Miami, FL MKC - Kansas City, MO MKG - Muskegon, MI MLC - Mc Calester, OK MLD - Malad City, ID MLP - Mullan Pass, ID MLS - Miles City, MT MLT - Millinocket, ME MLU - Monroe, LA MOD - Modesto, CA MOT - Minot, ND MPV - Montpelier, VT MQT - Marquette, MI MRF - Marfa, TX MSL - Muscle Shoals, AL MSP - Minneapolis, MN MSS - Massena, NY MSY - New Orleans, LA MTU - Myton, UT MZB - Mission Bay, CA OAK - Oakland, CA OAL - Coaldale, NV OBH - Wolbach, NE OCS - Rocksprings, WY ODF - Toccoa, FL ODI - Nodine, MN OED - Medford, OR OKC - Oklahoma City, OK OMN - Ormond Beach, FL ONL - Oneill, NE ONP - Newport, OR ORD - O Hare Intl, IL ORF - Norfolk, VA ORL - Orlando, FL OSW - Oswego, KS OVR - Omaha, NE PBI - West Palm Beach, FL PDT - Pendleton, OR PDX - Portland, OR PGS - Peach Springs, AZ PHX - Phoenix, AZ PIE - Saint Petersburg, FL PIH - Pocatello, ID PIR - Pierre, SD PLB - Plattsburgh, NY PMM - Pullman, MI PQI - Presque Isle, ME PSB - Philipsburg, PA PSK - Dublin, VA PSX - Palacios, TX PUB - Pueblo, CO PVD - Providence, RI PWE - Pawnee City, NE PXV - Pocket City, IN PYE - Point Reyes, CA RAP - Rapid City, SD RBL - Red Bluff, CA RDU - Raleigh Durham, NC REO - Rome, OR C-3

62 Appendix C WA WS WST Plotting Map Decoder RHI - Rhinelander, WI RIC - Richmond, VA ROD - Rosewood, OH ROW - Roswell, NM RWF - Redwood Falls, MN RZC - Razorback, AR SAC - Sacramento - CA SAT - San Antonio, TX SAV - Savannah, GA SAX - Sparta, NJ SBY - Salisbury, MD SEA - Seattle, WA SGF - Springfield, MO SHR - Sheridan, WY SIE - Sea Isle, NJ SJI - Semmnes, AL SJN - St. Johns, AZ SJT - San Angelo, TX SLC - Salt Lake City, UT SLN - Salina, KS SLT - Slate Run, PA SNS - Salinas, CA SNY - Sidney, NE SPA - Spartanburg, SC SPS - Wichita Falls, TX SQS - Sidon, MS SRQ - Sarasota, FL SSM - Sault Ste Marie, MI SSO - San Simon, AZ STL - St. Louis, MO SYR - Syracuse, NY TBC - Tuba City - AZ TBE - Tobe, CO TCC - Tucumcari, NM TCS - Truth Or Consequences, NM TLH - Tallahassee, FL TOU - Neah Bay, WA TRM - Thermal, CA TTH - Terre Haute, IN TUL - Tulsa, OK TUS - Tucson, AZ TVC - Traverse City, MI TWF - Twin Falls, ID TXK - Texarkana, AR TXO - Texico, TX UIN - Quincy, IL VRB - Vero Beach, FL VUZ - Vulcan, AL VXV - Knoxville, TN YDC - Princeton, BC YKM - Yakima, WA YOW - Ottawa, ON YQB - Quebec, QB YQL - Lethbridge, AB YQT - Thunder Bay, ON YQV - Yorkton, SA YSC - Sherbrooke, QB YSJ - St. John, NB YVV - Wiarton, ON YWG - Winnipeg, MB YXC - Cranbrook, BC YXH - Medicine Hat, AB YYN - Swift Current, SA YYZ - Toronto, ON C-4

63 Appendix D Weather Radar Site Locations Map D-1

64 Appendix D Weather Radar Site Locations Map Identifiers Translator ABR - Aberdeen, SD ABX - Albuquerque, NM AKQ - Norfolk/Wakefield. VA AMA - Amarillo, TX AMX - Miami, FL APX - Gaylord, MI ARX - La Crosse, WI ATX - Seattle-Tacoma/Camano Island, WA BBX - Marysville/Beale AFB, CA BGM - Binghamton, NY BHX - Eureka/Bunker Hill, CA BIS - Bismarck, ND BLX - Billings/Yellowstone County, MT BMX - Birmingham/Alabaster, AL BOX - Boston/Taunton, MA BRO - Brownsville, TX BUF - Buffalo/Cheektowaga, NY BYX - Key West/Boca Chica Key, FL CAE - Columbia, SC CBW - Caribou/Hodgdon, ME CBX - Boise/Ada County, ID CCX - State College/Rush, PA CLE - Cleveland, OH CLX - Charleston/Grays, SC CRP - Corpus Christi, TX CXX - Burlington/Colchester, VT CYS - Cheyenne, WY DAX - Sacramento, CA DDC - Dodge City, KS DFX - Del Rio/Laughlin AFB, TX DIX - Philadelphia, PA/Fort Dix, NJ DLH - Duluth, MN DMX - Des Moines/Johnston, IA DOX - Dover AFB, DE DTX - Detroit-Pontiac/White Lake, MI DVN - Quad Cities/Davenport, IA DYX - Abilene/Dyess AFB, TX EAX - Kansas City/Pleasant Hill, MO EMX - Tuscon/Pima County, AZ ENX - Albany/East Berne, NY EOX - Fort Rucker, AL EPZ - El Paso, TX/Santa Teresa, NM ESX - Las Vegas/Nelson, NV EVX - Red Bay/Eglin AFB, FL EWX - Austin-San Antonio/New Braunfels, TX EYX - Edwards AFB, CA FCX - Roanoke/Coles Knob, VA FDR - Frederick/Altus AFB, OK FDX - Clovis/Cannon AFB, NM FFC - Atlanta/Peachtree City, GA FSD - Sioux Falls, SD FSX - Flagstaff/Coconino, AZ FTG - Denver/Boulder, CO FWS - Dallas/Fort Worth, TX GGW - Glasgow, MT GJX - Grand Junction/Mesa, CO GLD - Goodland, KS GRB - Green Bay/Ashwaubenon, WI GRK - Killeen/Fort Hood, TX GRR - Grand Rapids, MI GSP - Greenville-Spartanburg/Greer, SC GWX - Columbus AFB, MS GYX - Portland/Gray, ME HDX - Alamogordo/Holloman AFB, NM HGX - Houston-Galveston/Dickinson, TX HNX - San Joaquin Valley/Hanford, CA HPX - Fort Campbell, KY HTX - Hytop, AL ICT - Wichita, KS ICX - Cedar City, UT ILN - Cincinnati/Wilmington, OH ILX - Lincoln, IL IND - Indianapolis, IN INX - Tulsa/Inola, OK IWA - Phoenix/Mesa, AZ IWX - North Webster, IN D-2

65 Appendix D Weather Radar Site Locations Map Identifiers Translator JAN - Jackson, MS JAX - Jacksonville, FL JGX - Warner Robins/Robins AFB, GA JKL - Jackson/Noctor, KY LBB - Lubbock, TX LCH - Lake Charles, LA LIX - New Orleans-Baton Rouge/Slidell, LA LNX - North Platte/Thedford, NE LOT - Chicago/Romeoville, IL LRX - Elko/Sheep Creek Mountain, NV LSX - St. Louis/Research Park, MO LTX - Wilmington/Shallotte, NC LVX - Louisville/Fort Knox, KY LWX - Baltimore, MD-Washington, DC/Sterling, VA LZK - North Little Rock, AR MAF - Midland/Odessa, TX MBX - Minot AFB, ND MHX - Morehead City/Newport, NC MKX - Milwaukee/Dousman, WI MLB - Melbourne, FL MOB - Mobile, AL MPX - Minneapolis/Chanhassen, MN MQT - Marquette/Negaunee, MI MRX - Knoxville-Cities/Morristown, TN MSX - Missoula/Point Six Mountain, MT MTX - Salt Lake City/Promontory Point, UT MUX - San Francisco/Mt. Umunhum, CA MVX - Fargo-Grand Forks/Maryville, ND MXX - Carrville/Maxwell AFB, AL NKX - San Diego/Miramar NAS, CA NQA - Memphis/Millington, TN OAX - Omaha/Valley, NE OHX - Nashville/Old Hickory, TN OKX - New York City/Upton, NY OTX - Spokane, WA PAH - Paducah, KY PBZ - Pittsburgh/Coraopolis, PA PDT - Pendleton, OR POE - Fort Polk, LA PUX - Pueblo, CO RAX - Raleigh-Durham/Clayton, NC RGX - Reno/Virginia Peak, NV RIW - Riverton, WY RLX - Charleston/Ruthdale, WV RTX - Portland/Scappoose, OR SFX - Pocatello-Idaho Falls/Springman, ID SGF - Springfield, MO SHV - Shreveport, LA SJT - San Angelo, TX SOX - Santa Ana Mountains/ Orange County, CA SRX - Slatington Mountain, AR TBW - Tampa/Ruskin, FL TFX - Great Falls, MT TLH - Tallahassee, FL TLX - Oklahoma City/Norman, OK TWX - Topeka/Alma, KS TYX - Fort Drum, NY UDX - Rapid City/New Underwood, SD UEX - Hastings/Blue Hill, NE VAX - Valdosta/Moody AFB, GA VBX - Lompoc/Vandenberg AFB, CA VNX - Enid/Vance AFB, OK VTX - Los Angles/Sulphur Mountain, CA YUX - Yuma, AZ D-3

66 Appendix E National TAF Locations Western U.S. U.S. Government Image E-1

67 Appendix E National TAF Locations Central U.S. U.S. Government Image E-2

68 Appendix E National TAF Locations Eastern U.S. U.S. Government Image E-3

69 U.S. Government Image Appendix E Appendix E E-4

70 Appendix E Appendix E National TAF Locations Decoder ALABAMA (AL) CALIFORNIA (CA) (continued) ANB Anniston Anniston Metropolitan BHM Birminghan International DHN Dothan Airport HSV Huntsville Huntsville Intl-Carl T. Jones Field MOB Mobile Regional MGM Montgomery Dannelly Field MSL Muscle Shoals Regional TCL Tuscaloosa Municipal ARIZONA (AZ) DUG Douglas Bisbee-Douglas International FLG Flagstaff Pulliam GCN Grand Canyon Grand Canyon National Park PHX Phoenix Sky Harbor International PRC Prescott Ernest A. Love Field TUS Tucson International INW Winslow Municipal YUM Yuma Yuma MCAS/Yuma International PRB Paso Robles Municipal RBL Red Bluff Municipal RDD Redding Municipal SAC Sacramento Executive SAN San Diego International/Lindbergh Field SBA Santa Barbara Municipal SBP San Louis Obispo San Louis Obispo Co. McChesny Field SCK Stockton Metropolitan SFO San Francisco International SJC San Jose International SMF Sacramento Metropolitan SMX Santa Maria Public/Capt G. Allan Hancock Field SNA Santa Ana John Wayne-Orange County SNS Salinas Municipal STS Santa Rosa Sonoma County TRK Truckee Truckee-Tahoe TVL South Lake Tahoe Lake Tahoe UKI Ukiah Municipal VNY Van Nuys Airport ARKANSAS (AR) COLORADO (CO) ELD El Dorado S. Arkansas Regional at Goodwin Field FYV Fayetteville Drake Field FSM Fort Smith Regional HRO Harrison Boone County HOT Hot Springs Memorial Field JBR Jonesboro Municipal LIT Little Rock Adams Field PBF Pine Bluff Grider Field TXK Texarkana Regional-Webb Field CALIFORNIA (CA) ACV Arcata Airport BFL Bakersfield Meadows Field BIH Bishop Airport BLH Blythe Airport BUR Burbank Burbank-Glendale-Pasadena CEC Crescent Jack McNamara Field DAG Daggett Barstow-Daggett FAT Fresno Fresno Air Terminal IPL Imperial Imperial County WJF Lancaster General William J. Fox Airfield LGB Long Beach Long-Beach-Daugherty Field LAX Los Angeles International MCE Merced Municipal/MacReady Field MRY Monterey Peninsula EED Needles Airport OAK Oakland Metropolitan Oakland ONT Ontario International PSP Palm Springs Regional TRM Palm Springs Thermal PMD Palmdale Airport ALS Alamosa San Luis Valley Regional/Bergman Field APA Denver Centennial ASE Aspen Pitkin County Sardy Field BJC Denver Jeffco COS Colorado Springs Municipal DEN Denver International EGE Eagle Eagle County Regional GJT Grand Walker Field Junction GUC Gunnison Gunnison County HDN Hayden Yampa Valley MTJ Montrose Regional PUB Pueblo Memorial CONNECTICUT (CT) BDL Windsor Locks Bradley International BDR Bridgeport Igor I. Sikorsky DELEWARE (DE) ILG Wilmington New Castle County FLORIDA (FL) DAB Daytona Beach International EYW Key West International FLL Fort Lauderdale Ft. Lauderdale/Hollywood International FMY Fort Myers Page Field GNV Gainesville Regional JAX Jacksonville International MCO Orlando International E-5

71 Appendix E Appendix E National TAF Locations Decoder FLORIDA (FL) (continued) INDIANA (IN) MIA Miami International MLB Melbourne International PBI West Palm Beach International PFN Panama City Panama City-Bay County International PIE St. Petersburg/ International PNS Pensacola Regional RSW Fort Myers Southwest Florida International Clearwater SRQ Sarasota/ International Bradenton TLH Tallahassee Regional TPA Tampa International VRB Vero Beach Municipal GEORGIA (GA) ABY Albany Southwest Georgia Regional AGS Augusta Bush Field AHN Athens Athens/Ben Epps ATL Atlanta William B. Hartsfield CSG Columbus Metropolitan FTY Atlanta Fulton County-Brown Field MCN Macon Middle Georgia Regional SAV Savannah International SSI Brunswick Malcolm-McKinnon VLD Valdosta Regional IDAHO (ID) BOI Boise Air Terminal/Gowen Field BYI Burley Municipal COE Coeur D Alene Air Terminal SUN Hailey Friedman Memorial IDA Idaho Falls Fanning Field LWS Lewiston Lewiston-Nez Perce County PIH Pocatello Regional TWF Twin Falls Twin Falls-Sun Valley Regnl Joslin Field ILLINOIS (IL) CMI Champaign/Urbana University of Illinois-Willard DEC Decatur Airport DPA Chicago/W Chicago Dupage MDW Chicago Midway MLI Moline Quad-City ORD Chicago O Hare International PIA Peoria Greater Peoria Regional RFD Rockford Greater Rockford SPI Springfield Capital UIN Quincy Municipal Baldwin Field EVV Evansville Regional FWA Fort Wayne International IND Indianapolis International LAF Lafayette Purdue University SBN South Bend Michiana Regional Transportation Center HUF Terre Haute Hulman Regional IOWA (IA) ALO Waterloo Municipal BRL Burlington Regional CID Cedar Rapids Municipal DBQ Dubuque Regional DSM Des Moines International MCW Mason City Municipal OTM Ottumwa Industrial SUX Sioux City Sioux Gateway KANSAS (KS) CNU Chanute Chanute/Martin Johnson DDC Dodge City Regional GLD Goodland Renner Field/Municipal HUT Hutchinson Municipal MHK Manhattan Municipal RSL Russell Municipal SLN Salina Municipal FOE Topeka Forbes Field TOP Topeka Philip Billard Municipal ICT Wichita Wichita Mid-Continent KENTUCKY (KY) BWG Bowling Green Bowling Green-Warren County Regional CVG Covington/ Cincinnati/Northern Cincinnati LEX Lexington Blue Grass LOZ London London-Corbin-Magee Field PAH Paducah Barkley Regional SDF Louisville International Standiford Field LOUISIANA (LA) ESF Alexandria Esler Regional BTR Baton Rouge Metropolitan-Ryan Field LFT Lafayette Regional LCH Lake Charles Regional MLU Monroe Regional MSY New Orleans International SHV Shreveport Regional E-6

72 Appendix E Appendix E National TAF Locations Decoder MAINE (ME) MISSISSIPPI (MS) AUG Augusta State BGR Bangor International CAR Caribou Municipal HUL Houlton International PWM Portland International Jetport MARYLAND (MD) BWI Baltimore Baltimore-Washington MTN Baltimore Martin State SBY Salisbury Salisbury-Wicomico County Regional MASSACHUSETTS (MA) ACK Nantucket Memorial BAF Westfield Barnes Municipal BOS Boston General Edward Lawrence Logan Intl HYA Hyannis Barnstable Municipal-Boardman/ Polando Field ORH Worcester Municipal GLH Greenville Mid-Delta Regional GPT Gulfport Gulfport-Biloxi Regional GWO Greenwood Greenwood-Leflore JAN Jackson International MCB McComb McComb/Pike County/John E. Lewis Field MEI Meridian Key Field PIB Hattiesburg Hattiesburg/Laurel Regional TUP Tupelo Municipal-C.D. Lemons MISSOURI (MO) CGI Cape Girardeau Regional COU Columbia Regional JLN Joplin Regional MCI Kansas City International MKC Kansas City Downtown SGF Springfield Regional STJ St. Joseph Rosecrans Memorial STL St. Louis Lambert-St. Louis International SUS St. Louis Spirit of St. Louis MICHIGAN (MI) MONTANA (MT) APN Alpena Alpena County Regional AZO Kalamazoo Kalamazoo/Battle Creek International CMX Hancock Houghton County Memorial DET Detroit City DTW Detroit Metropolitan Wayne FNT Flint Bishop International GRR Grand Rapids Kent County International JXN Jackson Jackson County-Reynolds Field LAN Lansing Capital City MKG Muskegon Muskegon County MQT Marquette Marquette County PLN Pellston Pellston Regional Airport of Emmet County TVC Traverse City Cherry Capital MINNESOTA (MN) BIL Billings Billings Logan International BTM Butte Bert Mooney BZN Bozeman Gallatin Field CTB Cut Bank Municipal FCA Kalispell Glacier Park International GGW Glasgow International GTF Great Falls International HLN Helena Regional HVR Havre City-County LVM Livingston Mission Field LWT Lewistown Municipal MLS Miles City Frank Wiley Field MSO Missoula International SDY Sidney Sidney-Richland Municipal WYS West Yellowstone Yellowstone Airport AXN Alexandria Chandler Field BJI Bemidji Bemidji/Beltrami County BRD Brainerd Brainerd-Crow Wing County Regional DLH Duluth International HIB Hibbing Chisolm-Hibbing INL International Falls International Falls MSP Minneapolis Minneapolis-St. Paul International/ WOLD/Chamberlain RWF Redwood Falls Municipal RST Rochester International STC St. Cloud Regional NEBRASKA (NE) CDR Chadron Municipal GRI Grand Island Central Nebraska Regional LNK Lincoln Municipal OFK Norfolk Karl Stefan Memorial LBF North Platte North Platte Regional OMA Omaha Eppley Airfield BFF Scottsbluff William B. Helig Field NEVADA (NV) EKO Elko J.C. Harris Field ELY Ely Ely/Yelland Field LAS Las Vegas McCarren Field E-7

73 Appendix E Appendix E National TAF Locations Decoder NEVADA (NV) (continued) NEW YORK (NY) (continued) DRA Mercury Desert Rock LOL Lovelock Derby RNO Reno Reno/Tahoe International TPH Tonopah Airport WMC Winnemucca Municipal NEW HAMPSHIRE (NH) CON Concord Municipal LEB Lebanon Municipal MHT Manchester Airport PSM Portsmouth Pease International Tradeport NEW JERSEY (NJ) ACY Atlantic City Atlantic City International EWR Newark International MIV Millville Municipal TEB Teterboro Airport NEW MEXICO (NM) ABQ Albuquerque International CNM Carlsbad Cavern City Air Terminal DMN Deming Municipal GUP Gallup Municipal HOB Hobbs Lea County LVS Las Vegas Municipal ROW Roswell Industrial Air Center SAF Santa Fe County Municipal TCS Truth or Municipal Consequences TCC Tucumcari Municipal NEW YORK (NY) ALB Albany Albany County ART Watertown International BGM Binghamton Binghamton Regional/ Edwin A. Link Field BUF Buffalo Greater Buffalo International ELM Elmira Elmira/Corning Regional GFL Glens Falls Warren County HPN White Plains Westchester County IAG Niagara Falls International ISP Islip Long Island MacArthur ITH Ithaca Tompkins County JFK New York John F. Kennedy International JHW Jamestown Chautauqua County/Jamestown LGA New York La Guardia MSS Massena Massena International-Richards Field POU Poughkeepsie Dutchess County ROC Rochester Greater Rochester International SLK Saranac Lake Adirondack Regional SYR Syracuse Syracuse Hancock International UCA Utica Oneida County NORTH CAROLINA (NC) AVL Asheville Regional CLT Charlotte Charlotte/Douglas Municipal ECG Elizabeth City Coast Guard Air Station/Municipal EWN New Bern Craven County Regional FAY Fayetteville Regional/Grannis Field GSO Greensboro Piedmont Triad International HKY Hickory Regional ILM Wilmington New Hanover International INT Winston-Salem Smith Reynolds RDU Raleigh/Durham Raleigh-Durham International RWI Rocky Mount Rocky Mount-Wilson NORTH DAKOTA (ND) BIS Bismarck Municipal DIK Dickinson Municipal FAR Fargo Hector International GFK Grand Forks International ISN Williston Sloulin Field International JMS Jamestown Municipal MOT Minot International OHIO (OH) CAK Akron Akron-Canton Regional CLE Cleveland Cleveland-Hopkins International CMH Columbus Port Columbus International DAY Dayton James M. Cox Municipal FDY Findlay Airport LUK Cincinnati Municipal/Lunken Field MFD Mansfield Mansfield Lahm Municipal TOL Toledo Express YNG Youngstown/Warren Regional ZZV Zanesville Municipal OKLAHOMA (OK) GAG Gage Airport HBR Hobart Municipal MLC McAlester Regional OKC Oklahoma City Will Rogers World PNC Ponca City Municipal TUL Tulsa International OREGON (OR) AST Astoria Regional BKE Baker Baker City Municipal E-8

74 Appendix E Appendix E National TAF Locations Decoder OREGON (OR) (continued) SOUTH DAKOTA (SD) BNO Burns Municipal DLS The Dalles Municipal EUG Eugene Mahlon Sweet Field HIO Portland Portland-Hillsboro LMT Klamath Falls International MFR Medford Rogue Valley International Medford OTH North Bend Municipal PDT Pendleton Eastern Oregon Regional At Pendleton PDX Portland International RDM Redmond Roberts Field SLE Salem McNary Field TTD Troutdale Portland-Troutdale PENNSYLVANIA (PA) ABE Allentown Lehigh Valley International AGC Pittsburgh Allegheny County AOO Altoona Airport-Blair County AVP Wilkes-Barre/ International Scranton BFD Bradford Regional BVI Beaver Falls Beaver County DUJ DuBois DuBois/Jefferson County ERI Erie International FKL Franklin Venango Regional IPT Williamsport Williamsport-Lycoming County Regional JST Johnstown Johnstown/Cambria County LBE Latrobe Westmoreland County MDT Harrisburg International/Middletown PHL Philadelphia International PIT Pittsburgh International PNE Philadelphia Northeast Philadelphia RDG Reading Regional/Carl A. Spaatz Field UNV State College University Park RHODE ISLAND (RI) PVD Providence Theodore Francis Green State SOUTH CAROLINA (SC) AND Anderson Anderson City CAE Columbia Metropolitan CHS Charleston Charleston AFB/International CRE North Myrtle- Grand Strand Beach FLO Florence Florence City-County GMU Greenville Downtown GSP Greenville Greenville-Spartanburg Intl Airport/Greer MYR Myrtle Beach Regional ABR Aberdeen Regional ATY Watertown Municipal FSD Sioux Falls Joe Foss Field HON Huron Regional PIR Pierre Regional RAP Rapid City Regional TENNESSEE (TN) BNA Nashville International CHA Chattanooga Lovell Field CSV Crossville Memorial MEM Memphis International MKL Jackson McKellar-Sipes Regional TRI Bristol/Johnson/ Tri-City Regional Tennessee Valley Kingsport TYS Knoxville McGhee Tyson TEXAS (TX) ABI Abilene Regional ACT Waco Regional ALI Alice International AMA Amarillo International AUS Austin Robert Mueller BPT Beaumont/ Jefferson County Port Arthur BRO Brownsville Brownsville/South Padre Island Intl CDS Childress Municipal CLL College Station Easterwood Field CRP Corpus Christi International DAL Dallas Love Field DFW Dallas-Fort Worth International DHT Dalhart Municipal ELP El Paso International FTW Fort Worth Meacham International GGG Longview Gregg County GLS Galveston Scholes Field HOU Houston William P. Hobby HRL Harlingen Rio Grande Valley International IAH Houston Intercontinental INK Wink Winkler County LBB Lubbock International LFK Lufkin Angelina County LRD Laredo International MAF Midland International MFE McAllen McAllen Miller International SAT San Antonio International SJT San Angelo Mathis Field SPS Wichita Falls Sheppard AFB/Wichita Falls Municipal TYR Tyler Pounds Field VCT Victoria Regional E-9

75 Appendix E Appendix E National TAF Locations Decoder UTAH (UT) WEST VIRGINIA (WV) (continued) BCE Bryce Canyon Airport CDC Cedar City Municipal OGD Ogden Ogden-Hinkley PVU Provo Municipal SLC Salt Lake International VEL Vernal Airport ENV Wendover Airport HTS Huntington Tri-State/Milton J. Ferguson Field LWB Lewisburg Greenbrier Valley MGW Morgantown Municipal/Walter L. Bill Hart Field MRB Martinsburg Eastern WV Regional PKB Parkersburg Wood County/Gill Robb Wilson Field WISCONSIN (WI) VERMONT (VT) BTV Burlington International MPV Montpelier Edward F. Knapp State VIRGINIA (VA) CHO Charlottesville Charlottesville-Regional DAN Danville Regional LYH Lynchburg Regional/Preston Glenn Field PHF Newport News Newport News/Williamsburg International ORF Norfolk International RIC Richmond International ROA Roanoke Regional/Woodrum Field WASHINGTON (WA) ALW Walla Walla Regional BFI Seattle Boeing Field/King County International BLI Bellingham International CLM Port Angeles William R. Fairchild International EAT Wenatchee Pangborn Memorial GEG Spokane International HQM Hoquiam Bowerman MWH Moses Lake Grant County OLM Olympia Airport PAE Everett Snohomish County/Paine Field PSC Pasco Tri-Cities SEA Seattle Seattle-Tacoma International SFF Spokane Felts Field YKM Yakima Air Terminal AUW Wausau Downtown CWA Mosinee Central Wisconsin EAU Eau Claire Chippewa Valley Regional GRB Green Bay Austin Strauble International LSE LaCrosse Municipal MKE Milwaukee General Mitchell International MSN Madison Dane County Regional/Truax Field OSH Oshkosh Wittman Regional (July & August only) WYOMING (WY) CPR Casper Natrona County International CYS Cheyenne Airport COD Cody Yellowstone Regional GCC Gillette Gillette-Campbell County JAC Jackson Jackson Hole LND Lander Hunt Field LAR Laramie Regional RWL Rawlins Municipal RIW Riverton Regional RKS Rock Springs Rock Springs-Sweetwater County SHR Sheridan Sheridan County WRL Worland Municipal WASHINGTON, D.C. DCA Washington, D.C. Washington National IAD Washington Washington-Dulles WEST VIRGINIA (WV) BKW Beckley Raleigh County Memorial BLF Bluefield Mercer County CKB Clarksburg Benedum CRW Charleston Yeager EKN Elkins Elkins-Randolph County-Jennings Randolph Field HLG Wheeling Wheeling-Ohio County E-10

76 Appendix F Clouds, Clues, and Effects on Flight Below, is a list of general observations a pilot can make regarding clues for recognizing stable or unstable air and clouds: Dust devils rising from the surface indicate dry, unstable air ascending to a considerable height above. Climb above the unstable air to avoid a bumpy ride. Showery clouds towering quickly upwards indicate turbulence under and through the clouds. Fly around these clouds. Fair weather cumulus clouds typically have turbulence beneath and within the clouds. Climbing above the cloud tops will smooth out your ride. If VFR, do not get trapped on top of an overcast. As you climb, watch your OAT. If the temperature uniformly and rapidly decreases, the air is unstable. As you climb, watch your OAT. If the temperature remains unchanged, the air is stable. If the air at the surface is warm and moist (hot, summer day), the air is unstable. Thunderstorms are a definite sign of unstable, turbulent air. Steer well clear of all thunderstorms. A brief description of cloud types and their effects on flight follows: Cloud Type Effects on Flight High Clouds develop above 20,000 feet AGL, usually in stable air: cirrus cirrocumulus cirrostratus no significant icing; turbulence in dense, banded cirrus. may contain highly supercooled water droplets resulting in some turbulence and icing. little if any icing; no turbulence; restricted visibility. Mid-Level Clouds form around 6,500 feet AGL, extending up to 20,000 feet AGL: altocumulus altostratus small amounts of icing; some turbulence. moderate amounts of icing; little to no turbulence; restricted sunlight. altocumulus castellanus unstable air;rough turbulence with some icing. standing lenticular altocumulus clouds very strong turbulence. Low Clouds form near the surface and extend up to 6,500 feet AGL: nimbostratus stratus stratocumulus cumulus towering cumulus very little turbulence; can pose serious icing problems if temperatures are near or below freezing. little or no turbulence; hazardous icing conditions if temperatures are near or below freezing; when associated with fog or precipitation, can create conditions of greatly reduced visibility. some turbulence; possible icing at subfreezing temperatures; ceiling and visibility better than with low stratus clouds. shallow layer of unstable air will give some turbulence, but no significant icing. very strong turbulence with rain showers; some clear icing above the freezing level. cumulonimbus (thunderstorm) unstable air throughout; violent turbulence; strong possibility for icing. Whenever you see or hear the term nimbo or nimbus, think rain. Whenever you see or hear the term strato or stratus, think stable air. Whenever you see or hear the term cumulo or cumulus. think unstable air. Whenever you see or hear the terms CB or cumulonimbus, think thunderstorm. Whenever you see or hear the terms BLDG CU building cumulus TCU towering cumulus, think developing thunderstorms. F-1

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