Preflight Weather Analysis Lesson 2 Part 2 of 4

Transcription

1 Preflight Weather Analysis Lesson 2 Part 2 of 4 Presented by Find-it Fast Books Unlimited FREE Downloads of this course available at 1

2 NATIONAL MOSAIC RADAR CHART Precipitation Imagery Our next look at the weather focuses on precipitation. The above image is the National Mosaic Radar Chart. This overview will give you a basic understanding of the types of radar images and what the precipitation echo color coding represents. Reference: Page 11 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 2

3 NATIONAL MOSAIC RADAR CHART Precipitation displayed on this radar chart is less than 15 minutes old. Looped imaging shows direction and rate of movement of precipitation. Blue and green color coding indicates light precipitation. Yellow indicates moderate intensity. Orange, red and purple colors indicate heavy to extreme precipitation, hail and possible thunderstorms. Reference: Page 11 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 3

4 NATIONAL MOSAIC RADAR CHART The National Mosaic Radar Chart is composed of a network of 158 Doppler radar sites located throughout the United States. Precipitation location and movement within 124 NM of each individual radar site is depicted to form this national composite radar picture. Reference: Page 11 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 4

5 The next slide depicts the National Mosaic, with the 10 Regional Doppler Radars placed below. These images are available at NOAA's National Weather Service Aviation Weather Center, Aviation Digital Data Service, or ADDS website -- The Regional images give you closer detail to help in analyzing precipitation intensities and movement. Clicking on them on the Website enlarges their images. 5

6 NATIONAL MOSAIC Reference: Page 11 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 6

7 REGIONAL BASE REFLECTIVITY IMAGE This image is the Lower Mississippi Valley Regional sector. One of the 10 regional Doppler Radar sectors covering the continental United States. When combined, this and the other nine Sectors, create the National Mosaic Radar Chart shown on the previous slides. 5 to 10 Minute Image Updates Precipitation Direction and Speed Color Coded Precipitation Intensities Reference: Page 13 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 7

8 JACKSON, MS DOPPLER RADAR SITE This image is the Jackson, MS individual Doppler Radar Site which is part of the Lower Mississippi Valley Sector regional sector on the previous slide. The radar site is located in the center. Each of the 158 individual radar sites provide even greater detail of precipitation echoes. The light blue echoes located in the center are ground clutter. Some isolated cells of precipitation are depicted. 1 of the 158 Doppler Radar Sites Greater Detail Light Blue is Ground Clutter Reference: Page 13 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 8

9 The WSR-88D Doppler Radar network is the best method for evaluating the thunderstorm threat in almost real-time. General echo intensity is depicted by color coding ranging from light blue through purple up to white. Progressively heavier precipitation increases the severity of flight hazards. Echoes of blue to light green, in many cases, is very light precipitation that does not reach the ground. The next few slides review color coding and effects. 9

10 WSR-88D DOPPLER RADAR General Echo Intensity Color Codes and Effects Blue Through Light Green: Light Precipitation Little or No Turbulence Possible Reduced Visibility Precipitation May Not Reach the Ground (Virga) Reference: Page 13 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 10

11 WSR-88D DOPPLER RADAR General Echo Intensity Color Codes and Effects Dark Green Through Yellow: Moderate Precipitation Moderate Turbulence Possible Low Visibility Reference: Page 13 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 11

12 WSR-88D DOPPLER RADAR General Echo Intensity Color Codes and Effects Orange and Red Through Purple: Heavy or Extreme Precipitation or Hail Severe Icing and Turbulence Thunderstorms Severe Aircraft Damage On rare occasions, white color coding may be contained within purple color coding, indicating an extremely intense form of precipitation. Reference: Page 13 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 12

13 WSR-88D DOPPLER RADAR Intensity Versus Tops Echo Legends INTENSITY - dbz stands for decibels relative to Z. It is a meteorological measure of equivalent reflectivity (Z) of a radar signal reflected off a remote object. In this case, precipitation. TOPS - KFT stands for thousands of feet in the measurement of precipitation echo TOPS. (Do not confuse with cloud tops!) Always note the radar chart legend you are using to determine if you are viewing echo intensity or echo tops. The next slide shows the similarity of the two color scales, emphasizing the importance of always determining the proper legend. 13

14 WSR-88D DOPPLER RADAR Intensity Versus Tops Echo Legends DBZ KFT DBZ = Intensity of Reflectivity KFT = Thousands of Feet Reference: Page 13 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 14

15 WSR-88D DOPPLER RADAR Intensity Versus Tops Echo Legends DBZ KFT DBZ = Intensity of Reflectivity KFT = Thousands of Feet The correlation between heavy precipitation echoes and high precipitation echo tops would imply thunderstorms when echo tops are above 18,000 feet as depicted on a radar chart. Reference: Page 13 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 15

16 CONVECTIVE OUTLOOK CHART The Convective Outlook Chart is a visual representation of the severe thunderstorm threat over a 3 day period. It is issued by NOAA s National Weather Service Storm Prediction Center, Website -- An outlook in text format is also issued, associated with the chart. Amendments are issued if current forecasts are inaccurate. The next ten slides explain the sequence of these charts. 16

17 CONVECTIVE OUTLOOK CHART Severe Thunderstorm Forecast 3 Charts Today -- Tomorrow -- Day After Tomorrow Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 17

18 The Day 1 Convective Outlook Chart is valid from 1200Z the same day it is issued until 1200Z on the following day. 4 more successive charts are issued throughout this day. CONVECTIVE OUTLOOK CHART Severe Thunderstorm Forecast Day 1 Chart Issued 5 Times Daily Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 18

19 CONVECTIVE OUTLOOK CHART The Day 2 Convective Outlook Chart is valid from 1200Z on the following day to 1200Z on the next day. Severe Thunderstorm Forecast Day 2 Chart Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 19

20 CONVECTIVE OUTLOOK CHART The Day 3 Convective Outlook Chart is valid from 1200Z on the third day after issuance until to 1200Z, the next day. Severe Thunderstorm Forecast Day 3 Chart Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 20

21 CONVECTIVE OUTLOOK CHART There are 4 levels of risk defined by the Convective Outlook Chart: Slight, moderate, high risk, and see text. Levels of Severe Thunderstorm Risk: SLGT -- MDT -- HIGH SEE TEXT Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 21

22 CONVECTIVE OUTLOOK CHART Slight risk implies well organized severe thunderstorms are expected. But in small numbers and or low coverage. Levels of Severe Thunderstorm Risk: SLGT = Slight Risk Small Numbers and/or Low Coverage Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 22

23 CONVECTIVE OUTLOOK CHART Moderate risk implies a higher concentration of severe thunderstorms than the Slight concentration. And, in most situations, a greater magnitude of severe weather than the Slight designation. Levels of Severe Thunderstorm Risk: MDT = Moderate Risk Higher Concentration - Greater Magnitude Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 23

24 CONVECTIVE OUTLOOK CHART High risk almost always means a major severe weather outbreak is expected with great coverage -- or severe weather. There is also a strong likelihood of extreme severe events, such as violent tornadoes -- or unusually intense and damaging winds. Levels of Severe Thunderstorm Risk: HIGH = High Risk Severe Weather Event -- Possible Tornadoes Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 24

25 CONVECTIVE OUTLOOK CHART In areas depicted with See Text, refer to the appended Text based Convective Outlook for more information. This text is titled, Forecast Discussion. It is located directly below the Chart image. See Text is used in areas where thunderstorms may approach or exceed severe criteria. Levels of Severe Thunderstorm Risk: SEE TEXT TSTMS May Approach or Exceed Severe Criteria Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 25

26 A severe thunderstorm is defined as having: Wind gusts of 50 knots or greater. Or, hail 3/4 inch in diameter or greater Or, the occurrence of a tornado. CONVECTIVE OUTLOOK CHART Severe Thunderstorm Definition: Wind Gusts 50 Knots or Greater Hail 3/4 or Greater Occurrence of a Tornado Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 26

27 ATMOSPHERIC MOISTURE and STABILITY Another chart available for examination is the Lifted Index Chart. Valid twice a day, it measures moisture and stability retrieved from weather balloon soundings. Meteorologists use this data to develop thunderstorm forecasts. The next few slides briefly explain how to interpret this data. 27

28 ATMOSPHERIC MOISTURE and STABILITY Lifted Index Chart Valid Twice Daily Z and 1200Z Measures Moisture and Stability Meteorologist Forecast Tool Reference: Page 11 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 28

29 ATMOSPHERIC MOISTURE and STABILITY Each set of numbers on the Lifted Index chart has a numerator and a denominator: L over K. The L gives a numerical value for the stability or instability of the atmosphere. The K provides a numerical value for moisture content of the atmosphere. These two numbers, in combination, determine the likely severity and coverage of thunderstorms. 29

30 ATMOSPHERIC MOISTURE and STABILITY L = Stability K = Moisture L -- More Negative Numbers = Greater Chance of Thunderstorms K -- When High Numbers = Greater Coverage of Thunderstorms Reference: Page 11 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 30

31 On this chart, Alabama and Mississippi have the most unstable air and high moisture content combination on the chart. As a result, there is a high potential for severe thunderstorms in this area. ATMOSPHERIC MOISTURE and STABILITY Alabama & Mississippi Very Unstable Air High Moisture Content High Potential for Severe Thunderstorms Reference: Page 11 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 31

32 ATMOSPHERIC MOISTURE and STABILITY Here is a closer look of the Alabama Mississippi area to help you see the numbers more clearly. You can see that minus 4 is the top number - very unstable air. 32 and 39 are the bottom numbers - very high moisture content. This indicates a very high potential for severe thunderstorms! Alabama & Mississippi L - Top Number = Minus 4 = Very Unstable Air K - Bottom Numbers = 32 and 39 = High Moisture High Potential for Severe Thunderstorms Reference: Page 11 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 32

33 ATMOSPHERIC MOISTURE and STABILITY This general rule of thumb, indicating the development of thunderstorms, would most likely lead to a moderate to strong chance of severe thunderstorms with a coverage pattern of scattered to numerous storms. L = Stability K = Moisture General Rule of Thumb: When L is - 4 or Lower and K is 25 or Higher There are many variables associated with these probabilities, such as the synoptic picture, season, and location Severe Thunderstorms Are Very Likely Reference: Page 11 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 33

34 AIR MASS EFFECTS The general weather characteristics in relation to air moisture content and stability can be summarized below: Moist and Unstable Air: High Thunderstorm Potential Moist and Stable Air: Low Stratus Clouds and Precipitation Dry and Unstable Air: Few or No Clouds - But With Thermals Thermals are columns of rising air in the lower altitudes created by uneven heating of the Earth s surface from solar radiation. Dry and Stable Air: Few or No Clouds Reference: Page 9 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 34

35 SEVERE WEATHER WATCH ALERT MESSAGE (AWW) A Severe Weather Watch Alert Message (AWW) is issued before a Severe Weather Watch (WW) as a preliminary notification to flight service and other weather specialists. The Severe Weather Watch Alert Message offers a quick overview of affected areas. The severe weather phenomenon can be severe thunderstorms and / or tornadoes. See the example on the next slide. 35

36 SEVERE WEATHER WATCH ALERT MESSAGE (AWW) SPC AWW WW 526 SEVERE TSTM IA IL Z Z AXIS.. 45 STATUTE MILES EITHER SIDE OF A LINE.. 25WNW CID/CEDAR RAPIDS IA/ - 15E MLI/MOLINE IL / AVIATION COORDS.. 40NM EITHER SIDE /39NW IOW 33 WNW BDF / HAIL SURFACE AND ALOFT INCHES. WIND GUSTS.. 70 KNOTS. MAX TOPS TO 500. MEAN STORM MOTION VECTOR Unscheduled Severe Thunderstorm Alert Quick Overview of Affected Area Issued Before Severe Weather Watch Bulletin Reference: Page 18 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 36

37 SEVERE WEATHER WATCH ALERT MESSAGE (AWW) Severe weather watches are issued when conditions are favorable for the development of severe thunderstorms and or tornadoes -- that is, high atmospheric moisture content and instability. The unscheduled severe weather watch box defines the potentially affected area. On the next slide, you can see at a quick glance that the noted portions of Illinois and Iowa are the affected areas. On very rare occasions, the severe weather does not develop. Always assume it will. 37

38 SEVERE WEATHER WATCH MESSAGE (WW) Follows 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) Reference: Page 18 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 38

39 SEVERE WEATHER WATCH MESSAGE 529 PLOT Using the National Plotting Map, based on the locations of high altitude VORs, this is the graphical plot of the Severe Weather Watch as defined by the AXIS coordinates in the previous message. The next slide zooms in, a little to gibe you a little more detail. Plotted Location - Eastern Iowa and NW ILLinois Reference: Page 18 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 39

40 SEVERE WEATHER WATCH MESSAGE 529 PLOT Here is a closer look at the affected portion of the previous slide.. Weather Watch status report messages may be issued referring to current Watch boxes. These updated messages will often cancel a portion of the original box, if the weather threat diminishes. It s not uncommon to have multiple Weather Watch boxes which may overlap. Looking at the states listed on each Weather Watch can help sort them out. A Closer Look Plotted Location - Eastern Iowa and NW ILLinois Reference: Page 18 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 40

41 WATCH Versus WARNING When severe thunderstorms or tornadoes have developed within a Weather Watch Box issued by the Storm Prediction Center, local Warnings will be issued for the now observed thunderstorms or tornadoes by the local weather forecast office. The original Weather Watch remains in effect even though a Warning has been issued. See the next slide for a simplified comparison of WATCH versus WARNING. 41

42 WATCH Versus WARNING WATCH: Conditions Favorable for Severe Thunderstorm or Tornado Development WARNING: Observed Severe Thunderstorms or Tornadoes within the Weather Watch Area Reference: Page 18 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 42

43 CONVECTIVE SIGMET (WST) Convective Sigmets are always issued at 55 minutes past every hour for each of the three regions -- Eastern, Central, Western. An individual Convective Sigmet is issued for every convective event and each one is identified by a letter and number combination. A Convective Sigmet is valid for up to 2 hours, but it can be canceled or updated by a subsequent Convective Sigmet. See the next slide for an example. 43

44 CONVECTIVE SIGMET (WST) MKCC WST CONVECTIVE SIGMET 39C VALID UNTIL 1355Z TX OK KS MO LA NM FROM 40S GLD-30E SGF-LIT-30SE SAT-20N ROW-40S GLD AREA SEV TS MOV FROM 30025KT. TOPS ABV FL450. HAIL TO 1.5 IN... WIND GUSTS TO 60KT POSS. END 55 Minutes Past Every Hour 3 Regions: Eastern -- Central -- Western Valid for 2 Hours GLD=Goodland, KS -- SGF=Springfield, MO -- LIT=Little Rock, AR -- SAT=San Antonio, TX -- ROW=Roswell, NM Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 44

45 CONVECTIVE SIGMET (WST) Using the National Plotting Map, based on the locations of high altitude VORs, the text based points of Convective Sigmet 39C, on the previous slide, are plotted as shown on this slide. Quite a large area, in this case. The specific location of the thunderstorms within the defined area is NOT given. WST 39C Examining Doppler radar will show where the thunderstorms actually are located. Plotted Convective Sigmet 39C An AREA of Active Thunderstorms Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 45

46 CONVECTIVE SIGMET (WST) MKCC WST CONVECTIVE SIGMET 39C VALID UNTIL 1355Z TX OK KS MO LA NM FROM 40S GLD-30E SGF-LIT-30SE SAT-20N ROW-40S GLD AREA SEV TS MOV FROM 30025KT. TOPS ABV FL450. HAIL TO 1.5 IN... WIND GUSTS TO 60KT POSS. This Convective Sigmet, 39C, has been issued for the Central Region, defined by the MKCC in the header. END MKC = Kansas City, MO (NOAA Aviation Weather Center) C = Central Region MKC stands for Kansas City, the issuing office, NOAA s Aviation Weather Center, in Kansas City, MO. And the second C stands for the Central Region. Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 46

47 CONVECTIVE SIGMET (WST) The three regions defined by the lines on this map overlap a little to address situations where thunderstorms move from one region into another. Western Central Eastern MKCW MKCC MKCE Two advisories may be issued by two regions, such as West and Central, repeating most of the same information. Check carefully. Often there are slight differences between the two advisories. Convective Sigmet Regions Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 47

48 CONVECTIVE SIGMET (WST) If No Convective SIGMET is Issued for a particular Region then that Region issues a negative statement: CONVECTIVE SIGMET...NONE Negative Statements Always at 55 Past the Hour Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 48

49 CONVECTIVE SIGMET (WST) If the CONVECTIVE SIGMET contains only forecast information, it is called an Outlook. Convective Sigmet Outlooks provide some information in the text, but refer the reader to the most recent one-day anticipated convection report from the Norman, Oklahoma Storm Prediction Center. A method for locating the ACUS01 KWNS described on the next slide is to enter the search phrase into an Internet search engine. Be sure to note the date / time group to make sure it is the current anticipated convection report. 49

50 CONVECTIVE SIGMET (WST) OUTLOOK MKCW WST CONVECTIVE SIGMET...NONE OUTLOOK VALID FROM 60N ABQ-40W ELP-70SSW DMN-50S TUS-INW-60N ABQ WST ISSUANCES POSS LT IN PD. REFER TO MOST RECENT ACUS01 KWNS FROM STORM PREDICTION CENTER FOR SYNOPSIS AND METEOROLOGICAL DETAILS. ACUS01 = The one-day anticipated convection (AC) report KWNS = Station id for Norman, Oklahoma Storm Prediction Center Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 50

51 CONVECTIVE SIGMET (WST) All Convective Sigmets Imply: IFR Conditions Severe or Greater Turbulence Severe Icing Low-Level Wind Shear Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 51

52 CONVECTIVE SIGMET (WST) All Thunderstorms Contain: Turbulence Hail Rain Snow Lightning Sustained Updrafts and Downdrafts Icing Conditions Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 52

53 CONVECTIVE SIGMET (WST) MKCC WST CONVECTIVE SIGMET 39C VALID UNTIL 1355Z TX OK KS MO LA NM FROM 40S GLD-30E SGF-LIT-30SE SAT-20N ROW-40S GLD AREA SEV TS MOV FROM 30025KT. TOPS ABV FL450. HAIL TO 1.5 IN... WIND GUSTS TO 60KT POSS. END Issued When These Conditions Exist or are Forecast: Severe Thunderstorms Embedded Thunderstorms Line of Thunderstorms Active Area of Thunderstorms Tornadoes Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 53

54 CONVECTIVE SIGMET (WST) A Severe Thunderstorm is Defined as Having: Surface Winds 50 Knots or Greater Hail 3/4 Inch or Greater Tornadoes Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 54

55 CONVECTIVE SIGMET (WST) An Embedded Thunderstorm is Defined as Being: Hidden by: Haze Clouds Precipitation Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 55

56 CONVECTIVE SIGMET (WST) A Line of Thunderstorms is Defined by a Line with: 40% or More Coverage of a Line 60 Miles or Longer Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 56

57 CONVECTIVE SIGMET (WST) An Active Area of Thunderstorms is Defined as: Affecting at Least 3,000 Square Miles Very Heavy or Greater Intensity Rain Affecting 40% or More of the Area Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 57

58 CONVECTIVE SIGMET (WST) Thunderstorm Coverages Defined: ISOL = Isolated WDLY SCT = Widely Scattered SCT = Scattered Area = Area NMRS = Numerous WDSPRD = Widespread Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 58

59 CONVECTIVE SIGMET (WST) ISOL = Isolated Single Cells No Percentage of Coverage Given for the Affected Area The specific location of the thunderstorms within the defined area is NOT given. Examining Doppler radar will show where the thunderstorms actually are located. Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 59

60 CONVECTIVE SIGMET (WST) WDLY SCT = Widely Scattered Less Than 25% Coverage of Affected Area SCT = Scattered or AREA 25% to 54% Coverage The specific location of the thunderstorms within the defined area is NOT given. Examining Doppler radar will show where the thunderstorms actually are located. Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 60

61 CONVECTIVE SIGMET (WST) NMRS = Numerous or WDSPRD = Widespread 55% or More Coverage of Affected Area The specific location of the thunderstorms within the defined area is NOT given. Examining Doppler radar will show where the thunderstorms actually are located. Reference: Page 19 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 61

62 AIRMET (WA) AIRman s METeorological Information Typical AIRMET Format CHIT WA AIRMET TANGO UPDATE 3 FOR TURB VALID UNTIL AIRMET TURB MN ND SD NE FROM BJI TO OBH TO BFF TO 50NNW ISN TO BJI MOD TURB BLW 120. CONDS CONTG BYD 03Z THRU 09Z. An AIRMET, or Airman s Meteorological Information, advises of weather that maybe hazardous, other than convective activity, to single engine, other light aircraft, and Visual Flight Rule (VFR) pilots. However, operators of large aircraft may also be concerned with these phenomena. Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 62

63 AIRMET (WA) AIRMETs concern less severe weather than that of SIGMETs or Convective SIGMETs. SIGMETS will be discussed later in this lesson. 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. An AIRMET can also be described as a concise description of the occurrence or expected occurrence of specified en route weather phenomena which may affect the safety of aircraft operations, but at intensities lower than those which require the issuance of a SIGMET. 63

64 AIRMET (WA) Less Severe Than SIGMET or Convective SIGMET AIRMET -- An In-flight Advisory Concerning: Adverse Weather Conditions of Interest to all Aircraft Potentially hazardous to aircraft with limited capability due to lack of proper equipment, instrumentation, or pilot qualifications which may affect safety of aircraft operations at intensities lower than SIGMET Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 64

65 AIRMET (WA) The Adverse Condition of an AIRMET Affects or is Forecast to Affect: An Area of at Least 3,000 Square Miles in Size Only a Portion of the Total Area May be Affected The Question is... Where? Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 65

66 AIRMET (WA) Issued Every Six Hours Valid for Six Hours Can Be Unscheduled Issuances Occurrence or Expected Occurrence of Widespread Adverse Weather: Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 66

67 AIRMET (WA) Adverse Conditions Described: Ceiling Less Than 1,000 Feet Visibility Less Than 3 Statute Miles Mountain Obscuration Moderate Icing Freezing Levels Moderate Turbulence Low Level Wind Shear Sustained Surface Winds Greater Than 30 Knots 67

68 AIRMET (WA) You will notice on the following slides, each AIRMET has 3 letters preceding the type of AIRMET describing the adverse condition. This 3 letter designator refers to the area of responsibility of the issuing office. As you can see on the map on the next slide, there are 6 areas of responsibility. If similar adverse conditions exist in an adjoining area, an AIRMET will be issued describing those conditions with a 3 letter header defining that area, as well. 68

69 AIRMET (WA) Geographic Areas of Responsibility Each area issues its own set of AIRMETs Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 69

70 AIRMET (WA) If you are planning an extended route of flight, always check adjoining areas of responsibility for the adverse conditions described in that AIRMET to determine if they will continue to affect your flight. There may be multiple AIRMETS for more than one adverse condition and / or location. Be sure you review the AIRMETS pertinent to your route of flight, and AIRMET areas that may drift into your route in the future. 70

71 AIRMET (WA) Geographic Areas of Responsibility For Extended Routes of Flight Check Adjoining Areas Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 71

72 AIRMET (WA) The 3 Alphabetic Designations for AIRMETS are: AIRMET Z -- Zulu Icing AIRMET T -- Tango Turbulence and Strong Winds AIRMET S -- Sierra IFR Conditions Mountain Obscuration Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 72

73 AIRMET (WA) AIRMET Z -- Zulu Concerns: Moderate Icing -- MOD ICE Does NOT Indicate: Whether in Clouds or in Precipitation -- or -- Type of Icing (Rime / Mixed / Clear) SFC = Freezing Level at Surface An AIRMET does NOT indicate whether in clouds or in precipitation -- or -- type of icing: (Rime / Mixed / Clear). If the freezing level is at the surface, it will be defined by the contraction SFC. Reference: Page 22 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 73

74 AIRMET (WA) BOSZ WA AIRMET ZULU UPDATE 3 FOR ICE AND FRZLVL VALID UNTIL AIRMET ICE NY PA OH MI LE WV MD FROM BUF TO 50E EKN TO CVG TO FWA TO DXO TO BUF MOD ICE BTN 030 AND 100. CONDS CONTG BYD 03Z THRU 09Z. The VOR plotting points for this AIRMET Zulu for icing are depicted below the text so you can see the defined area. You can get a quick feel for the location of the advisory area by reading the line listing the affected states. Don t assume the whole state is affected, however. For example, as you can see by looking at western New York, just a small portion of the state is included. BUF=Buffalo NY -- EKN=Elkins, WV -- CVG=Covington, KY -- FWA=Fort Wayne, IN -- DXO=Detroit, MI Reference: Page 22 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 74

75 AIRMET (WA) AIRMET T -- Tango Concerns: Moderate Turbulence -- MOD TURB Low Level Wind Shear -- LLWS Sustained Surface Winds Greater Than 30 Knots STG SFC WND Does NOT Indicate: Cause and Direction of Winds Reference: Page 23 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 75

76 AIRMET (WA) CHIT WA AIRMET TANGO UPDATE 3 FOR TURB VALID UNTIL AIRMET TURB MN ND SD NE FROM BJI TO OBH TO BFF TO 50NNW ISN TO BJI MOD TURB BLW 120. CONDS CONTG BYD 03Z THRU 09Z. The VOR plotting points for this AIRMET Tango for turbulence are depicted below the text so you can see the defined area. Again, you can get an idea for the location of the advisory area by reading the line listing the affected states. Don t assume a whole state is affected, however. For example, as you can see by looking at northern Nebraska, just a small portion of the state is included. BJI=Bemidjii, MN -- OBH=Wolbach, NE -- BFF=Scottsbluff, NE -- ISN=Williston, ND Reference: Page 23 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 76

77 AIRMET (WA) AIRMET S -- Sierra Concerns: Ceilings Less Than 1,000 Feet IFR, CIG BLW 010 and / or Visibility Less Than 3 Statute Miles IFR, VIS BLW 3 SM and / or Widespread Mountain Obscuration MTN OBSCN or MTOS Reference: Page 24 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 77

78 AIRMET (WA) SLCS WA AIRMET SIERRA UPDATE 3 FOR IFR AND MTN OBSCN VALID UNTIL AIRMET MTN OBSCN ID MT WY NV UT CO FROM SHR TO DEN TO BCE TO BAM TO SHR MTNS OCNL OBSC BY CLDS/PCPN/BR/FG. CONDS CONTG BYD 03Z THRU 09Z. The VOR plotting points for this AIRMET Sierra for mountain obscuration are depicted below the text so you can see the defined area. With AIRMET Sierra, as well, you can quickly determine the general location of the advisory area by reading the line listing the affected states. Don t assume a whole state is affected, however. For example, as you can see by looking at northeastern Nevada, just a small portion of the state is included. SHR=Sheridan, WY -- DEN=Denver, CO -- BCE=Bryce Canyon, UT -- BAM=Battle Mountain, NV Reference: Page 24 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 78

79 AIRMET (WA) If a SIGMET is Also in Effect: Similar Adverse Conditions Will be Referenced Example -- SEE SIGMET BRAVO SERIES Review the SIGMET! SIGMET: Severe Weather Having a Significant Effect on the Safety of Aircraft Operations (SIGMETs Will be Explained Later) Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 79

80 AIRMET (WA) OUTLOOK Adverse Weather Expected After 6 Hour AIRMET Period For Later Flights Always Look for Outlooks 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. These outlooks can be a critical factor in advanced flight planning. Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 80

81 AIRMET (WA) On the next slide is an example of an outlook for the continuation of IFR conditions as indicated by AIRMET Sierra. Notice that the valid time of the AIRMET ends at 0300 Zulu (highlighted by the red box). The outlook, (also highlighted by a red box) denoted by OTLK, then begins at 0300 Zulu, with IFR conditions continuing through 0900 Zulu. 81

82 AIRMET (WA) EXAMPLE OUTLOOK Adverse Weather Expected After 6 Hour AIRMET Period SFOS WA AIRMET SIERRA UPDT 4 FOR IFR VALID UNTIL AIRMET IFR...OR CA AND CSTL WTRS FROM 20SW ONP TO 30NNE FOT TO 30SSW FOT TO 20NNW SNS TO 60NW RZS TO 20WSW RZS TO 20SE LAX TO 20SE MZB TO 220SW MZB TO 140WSW FOT TO 20SW ONP CIG BLW 010/VIS BLW 3SM BR. CONDS CONTG BYD 03Z THRU 09Z. OTLK VALID Z...IFR WA OR CA AND CSTL WTRS BOUNDED BY 20N TOU-20ESE HQM-30S ONP-20SSW FOT-20SW ENI-20NNE PYE-20W RZS-30ESE RZS-50SE LAX-20S MZB-220SW MZB-140WSW FOT-70SW ONP-20N TOU CIG BLW 010/VIS BLW 3SM BR. CONDS CONTG THRU 09Z. Reference: Page 21 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 82

83 GRAPHICAL AIRMET (G-AIRMET) The NOAA Aviation Weather Center introduced the Graphical AIRMET in October, The next slide is an example of the Graphical AIRMET, or G-AIRMET, as it s also called. It is available at the Aviation Weather Center s Aviation Digital Data Service, ADDS, website, 83

84 GRAPHICAL AIRMET (G-AIRMET) Available at: ADDS - Aviation Digital Data Service - Aviation Weather Center 84

85 GRAPHICAL AIRMET (G-AIRMET) G-AIRMETs depict hazardous weather areas more accurately in time with more frequent updates changing the geographic areas associated with these updates. With a graphic presentation, they are easier to understand. They also offer selectable interactive graphics allowing you to click through the different time periods of the G-AIRMET s valid times. 85

86 GRAPHICAL AIRMET (G-AIRMET) G-AIRMET: More Precise Smaller Changing Areas 3 Hour Updates Text Based AIRMET: Broad Brush Large Unchanging Area 6 Hour Updates 86

87 GRAPHICAL AIRMET (G-AIRMET) Adverse Conditions are Same as Text AIRMET Ceiling Less Than 1,000 Feet Visibility Less Than 3 Statute Miles Mountain Obscuration Moderate Icing Freezing Levels Moderate Turbulence Low Level Wind Shear Sustained Surface Winds Greater Than 30 Knots 87

88 GRAPHICAL AIRMET (G-AIRMET) Examining the two maps, on the next slide, the map on the left shows the text based AIRMET depicting its broad brushed six hour time period, describing the area as moving southward. The G-AIRMET, on the other hand, describes this same area as developing southward, with the depicted areas pinpointing more precise position, shape, and size of the adverse condition with three distinct times within the text based AIRMET s time period. 88

89 GRAPHICAL AIRMET (G-AIRMET) Text Based AIRMET Area Moving Southward 00-06Z Large Area for 6 Hours Graphical AIRMET Area Developing Southward 00Z 03Z 06Z More Precise 89

90 SIGMET A SIGMET, or Significant Meteorological Information, is a Non-Convective weather advisory that contains meteorological information concerning the safety of all aircraft. 90

91 SIGMET Significant Meteorological Information Typical SIGMET Format: SFOX WS SIGMET XRAY 6 VALID UNTIL SIGMET CA FROM EHF TO TRM TO MZB TO LAX TO 40W RZS TO EHF OCNL SEV TURB BLW 120. CONDS CONTG BYD 0050Z Reference: Page 25 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 91

92 SIGMET Significant Meteorological Information of Expected or Occurring Non-Convective Weather Having a Significant Effect On the Safety Of All Aircraft Operations Reference: Page 25 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 92

93 SIGMET The Adverse Condition of a SIGMET Affects or is Forecast to Affect: An Area of at Least 3,000 Square Miles in Size Only a Portion of the Total Area May be Affected The Question is... Where? Reference: Page 25 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 93

94 SIGMET Alphabetic Designators for SIGMETS: November Through Yankee Maximum Forecast Period is Four Hours Reserved for AIRMETS: Sierra -- Tango -- Zulu SIGMETS are identified by alphabetic designators from November to Yankee. Each different hazardous weather condition requiring the issuance of a SIGMET across the country will have a different alphabetic designator. AIRMETS will always be identified by Sierra for low weather conditions, Tango for turbulence, and Zulu for icing. Reference: Page 25 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 94

95 SIGMET SIGMETs Describe: Severe Icing Severe Turbulence Extreme Turbulence Clear Air Turbulence -- CAT Mountain Waves Reference: Page 25 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 95

96 SIGMET SIGMETs Also Describe: Widespread Dust Storm -- WDSPRD DS (Inflight Visibilities Below 3 Statute Miles) Widespread Sandstorm -- WDSPRD SS (Inflight Visibilities Below 3 Statute Miles) Volcanic Ash -- VA Tropical Cyclone -- TC (Tropical Depression, Tropical Storm, Hurricane, Typhoon) Reference: Page 25 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 96

97 SIGMET You will notice on the following slides, each SIGMET has 3 letters preceding the type of SIGMET describing the adverse condition. This 3 letter designator refers to the area of responsibility of the issuing office. As you can see on the map on the next slide, there are 6 areas of responsibility. If similar adverse conditions exist in an adjoining area, a SIGMET will be issued describing those conditions with a 3 letter header defining that area, as well. 97

98 SIGMET Geographic Areas of Responsibility Each Area Issues its Own Set of SIGMETs Reference: Page 25 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 98

99 SIGMET If you are planning an extended route of flight, always be sure to check the adjoining areas of responsibility for the continuation of the weather hazards described in the SIGMET to determine if they will continue to affect your flight. 99

100 SIGMET Geographic Areas of Responsibility Each area issues its own set of SIGMETs Check Adjoining Areas on Long Flights Reference: Page 25 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 100

101 SIGMET SFOX WS SIGMET XRAY 6 VALID UNTIL SIGMET CA FROM EHF TO TRM TO MZB TO LAX TO 40W RZS TO EHF OCNL SEV TURB BLW 120. CONDS CONTG BYD 0050Z Notice that this SIGMET, XRAY 6, states conditions continuing beyond 0050 Zulu. The word beyond, (BYD) indicates a new SIGMET XRAY 7 will be valid at 0050 Zulu. Also, if the area of severe turbulence moves east into the Salt Lake (SLC) area of responsibility, the SIGMET header will change from SFO XRAY 6 to SLC XRAY 7. Plotted SIGMET XRAY 6 EHF=Bakersfield, CA -- TRM=Thermal, CA -- MZB=Mission Bay, CA -- LAX=Los Angeles, CA -- RZS=Santa Barb, CA Reference: Page 25 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 101

102 Center Weather Advisory A Center Weather Advisory is an unscheduled weather advisory issued for the guidance of ARTCC personnel and meteorologists, as well as air crews, to anticipate or avoid adverse weather conditions in terminal and en route control environments. The first line of a Center Weather Advisory has an ARTCC identifier, followed by a Number (1 through 6). The first weather event of the day which requires the issuance of a CWA is assigned number 1. If conditions are expected to continue after the advisory s valid period, a statement will be included in the last line of the text. 102

103 CENTER WEATHER ADVISORY ARTCC Identifier (CWA) ZME3 CWA ZME CWA 303 VALID TIL FROM MEM TO JAN TO LIT TO MEM OCNL TS MOV FM 24025KT. TOPS TO FL430 SAME MOVMT EXPD DRG THE NEXT 2 HRS Continuation Statement Typical Center Weather Advisory Format MEM=Memphis, TN -- JAN=Jackson, MS -- LIT=Little Rock, AR Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 103

104 CENTER WEATHER ADVISORY (CWA) Issued by National Weather Service CWSU (Center Weather Service Unit) One Unit at Each ARTCC 21 ARTCCs (ARTCC = Air Route Traffic Control Center) Center Weather Advisories are issued by Center Weather Service Units located at each of the 21 Air Route Traffic Control Centers -- Commonly referred to as Centers. Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 104

105 CENTER WEATHER ADVISORY (CWA) Center Weather Service Unit (CWSU) Areas of Responsibility One Unit at Each of 21 ARTCCs Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 105

106 Center Weather Advisory As you can see on the previous slide, there are 21 ARTCCs. If similar adverse conditions exist in an adjoining area, a Center Weather Advisory may be issued describing those conditions, as well. If you are planning an extended route of flight, always be sure to check the adjoining areas of responsibility for the continuation of the weather hazards described in the Center Weather Advisory to determine if they will continue to affect your flight. 106

107 Center Weather Advisory A Center Weather Advisory (CWA) is an aviation weather warning for conditions meeting or approaching the same criteria that is used for the issuance of AIRMETs, SIGMETs or Convective SIGMETs. The CWA is primarily used by pilots to anticipate and avoid adverse weather conditions in the enroute and terminal environments (Centers, Departure and Approach Controls). 107

108 CENTER WEATHER ADVISORY (CWA) An Aviation Weather Warning Message For Conditions Approaching or Meeting The Criteria of: AIRMETs SIGMETS Convective SIGMETS Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 108

109 CENTER WEATHER ADVISORY (CWA) Center weather Advisories are issued if any of the the below conditions occur, are forecast to occur, and, if previously forecast, are no longer expected. Conditions Meeting Convective SIGMET Criteria Icing -- Moderate or Greater Turbulence -- Moderate or Greater Heavy Precipitation Freezing Precipitation Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 109

110 Center Weather Advisory Center Weather Advisories are also issued if any of the the conditions listed on the next slide occur, are forecast to occur, and, if previously forecast, are no longer expected: Or, if in the forecaster's judgment, any other condition that may adversely impact the flow of air traffic within the ARTCC area of responsibility. 110

111 CENTER WEATHER ADVISORY (CWA) CWAs Issued For: Conditions at or Approaching Low IFR Surface Winds / Gusts >30 Knots Low Level Wind Shear (surface - 2,000 feet) Volcanic Ash, Dust Storms, or Sandstorms Conditions That May Adversely Impact the Flow of Air Traffic Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 111

112 CENTER WEATHER ADVISORY (CWA) Valid for up to Two Hours Hourly CWAs May be Issued for Convective Activity Impacting the Safe Flow of Air Traffic Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 112

113 CENTER WEATHER ADVISORY (CWA) May be Issued Preceding: AIRMETs SIGMETs Convective SIGMETs Or if Adversely Impacting CWSU Area Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 113

114 CENTER WEATHER ADVISORY (CWA) May be Issued to Refine: AIRMETs SIGMETs Convective SIGMETs Concerning Movement -- Extent -- Intensity Of Adverse Weather Event Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 114

115 CENTER WEATHER ADVISORY (CWA) May be Issued to Highlight: Significant Weather Not Meeting AIRMET -- SIGMET -- Convective SIGMET Criteria Adversely Impacting CWSU Area Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 115

116 URGENT CENTER WEATHER ADVISORY (UCWA) URGENT Center Weather Advisory UCWA Issued When Adverse Weather Has Not Been Forecast Has an Immediate Effect on ARTCC Air Traffic (ARTCC = Air Route Traffic Control Center) Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 116

117 Urgent Center Weather Advisory The Urgent CWA (UCWA) communications header is intended for those situations when weather conditions occur that have not been forecast and have an immediate effect on the safe flow of air traffic within the ARTCC area of responsibility. It should only be used when the CWSU meteorologist believes any delay in dissemination to FAA facilities would impact aviation safety. The routine CWA header for subsequent issuances of the same weather phenomenon will be used. 117

118 Meteorological Impact Statement (MIS) Unscheduled Flight Operations and Planning Forecast For ARTCC Flow Control Decisions Not Intended for Pilot Briefings Reference: Page 26 - Preflight Weather Analysis Made Easy, by Find-it Fast Books, website 118

119 Meteorological Impact Statement The Meteorological Impact Statement (MIS) is an unscheduled flow control and flight operations planning forecast. It is a non-technical forecast and briefing product for ATC personnel responsible for making flow controltype decisions. It is not used by flight service for briefings. The MIS details weather conditions expected to adversely impact air traffic flow in the CWSU area of responsibility, and is valid up to 12 hours after issuance time. The MIS may be effective immediately for existing conditions when CWSU operations begin, or for rapidly deteriorating conditions, or up to two hours in advance of expected conditions. 119

120 Preflight Weather Analysis End of Lesson 2 Go to Lesson 3 Presented by Find-it Fast Books Unlimited FREE Downloads of this course available at 120