Current Weather Studies 2 SURFACE WEATHER MAPS

Transcription

1 CWS 2-1 SP19 Current Weather Studies 2 SURFACE WEATHER MAPS Reference: Chapter 2 in the Weather Studies textbook. Complete the appropriate sections of Investigations in the Weather Studies Investigations Manual as directed by your mentor or instructor. Check for additional Weekly Weather News updates during the week. One of the learning objectives in Week 2 of this course is to summarize how meteorologists monitor surface and upper-atmospheric conditions, such as temperature, humidity, and winds. To that end, this Current Weather Studies highlights some of the weather conditions related to a recent significant air mass change in the upper High Plains and Great Lakes region and the associated precipitation types. As is common in the winter season, frequent incursions of cold, Arctic air move south out of Canada into the upper Midwest and Northeast U.S. The winter of thus far has not been immune from frequent cold air outbreaks. With those air mass exchanges, varying types of precipitation can take place during winter. As one might expect with Arctic air masses, falling snow can be synonymous with the leading edge of these very chilly air masses, with the impacts affecting many parts of the U.S. This activity examines the depiction of weather conditions through a variety of symbols used on surface weather maps from a late-january (2019) time frame. For a listing of the frequently occurring weather symbols, as well as a reference to the other symbols surrounding the station model circle, see the User s Guide linked from the RealTime Weather Portal, or go to For a more exhaustive set of 100 possible weather symbols which can be used in station models, go the NWS JetStream Max site at: Some of the items in this Current Study refer to symbols on this specific list.

2 CWS 2-2 SP19 Figure 1. Un-analyzed NCEP surface weather map for 13Z 30 January 2019 with station model plots conveying surface weather observations of temperature, moisture, pressure, cloud cover, and wind speed and direction. Figure 1 is the Midwest Data weather map from the RealTime Weather Portal, a regional map of surface weather conditions at 13Z 30 JAN This regional map in Figure 1 is an example of one of the seven regional maps provided from the Portal website, which shows a greater number of stations than is possible on the broad national-view map. The weather data observed at the stations are plotted around circles that represent the locations of those stations. The plotted weather conditions use the coded surface station model covered in the introductory portion of Manual Investigation 2A. 1. Recall from Current Studies Week 1 that there is a difference between universal time (Z) and local time. This regional map in Figure 1 is mostly focused on surface station reports in the Central time zone (CST). As such, the 13Z time-stamp on this map translates to local time (CST). a. 6 AM b. 7 AM c. 8 AM d. 9 AM

3 CWS 2-3 SP19 2. Multiple stations on this map, most notably in central Nebraska, do not have a wind barb or feather present at map time. Instead, these station model plots have a circle surrounding the station. This indicates that these stations were experiencing winds. a. varying b. calm c. strong 3. Looking at northern West Virginia in Figure 1, a station was reporting the green symbol with multiple asterisks in a tight cluster [ ] at the 9 o clock position alongside the station circle. This symbol showed that a continuous fall of snowflakes was occurring at a rate of intensity. a. light b. moderate c. heavy 4. In addition to weather symbols that indicate precipitation type and intensity, there are other symbols that report types of visibility reduction caused by weather. Specifically, on Figure 1 in eastern Iowa, there is a station with the green symbol [ ] at the 9 o clock position alongside the station circle. This symbol showed that was occurring. a. haze b. fog c. smoke d. dust e. blowing snow

4 CWS 2-4 SP19 Figure 2. Analyzed NCEP weather map with Isobars, Fronts, Radar & Data for 13Z 30 January 2019, the same time as the Figure 1 map. Figure 2 depicts the centers of high and low-pressure systems, fronts, and weather conditions plotted in surface map station models at a selection of stations across the contiguous U.S. at the same time as Figure 1. Colored shadings also show where the national network of weather radars detected precipitation across the U.S. In addition to the plotted station models, the surface weather map (Figure 2) contains an analysis of pressure patterns, such as the one you made in Investigation 1A. The centers of High Pressure on Figure 2 are marked by blue Hs, which also represent the centers of expansive air masses. One High was centered in the Central Missouri Valley region. An additional higher-pressure center is also marked in the central Rockies. Storm system centers, or Lows, are marked by red Ls. One Low was centered in central Ontario; another, weaker low, was located in southern Arizona. 5. Wind directions at the stations in the several-state region about the center of the extremely cold air mass in the Great Plains (the major High) are generally as seen from above. This may be confirmed by locating the H on Figure 2 centralized in Missouri and observing the wind barbs at station models surrounding the H, which display this circulation pattern. The hand-twist model may again be referenced here to further confirm your answer.

5 CWS 2-5 SP19 a. counterclockwise and inward b. counterclockwise and outward c. clockwise and inward d. clockwise and outward 6. In one of the coldest regions of the U.S. at map time, observe the station model for Bismarck (in central North Dakota) in Figure 2. The station model shows a temperature of degrees F. a. 0 b. -11 c. -21 d Further to the east from North Dakota, the dewpoint temperature at Minneapolis, Minnesota was degrees F. a. -18 b. -28 c. -35 d Winds at stations are symbolized and identified by the direction from which they blow. The wind at Minneapolis was generally from the. a. north b. east c. south d. west 9. The wind speed, rounded off to the nearest 5 knots, is shown by a combination of feathers along the direction shaft, where a long feather denotes 10 knots and a short feather is 5 knots. A single long feather at the tail end of the arrow shaft signifies Minneapolis wind speed is about knots. a. 5 b. 10 c. 15 d. 50

6 CWS 2-6 SP The coded pressure value at Minneapolis was plotted as 282, meaning the actual atmospheric pressure corrected to sea level was mb. a b c d The sky cover (designated by the amount of coverage inside the station circle) at Minneapolis indicated conditions. a. clear b. partly cloudy c. mostly cloudy d. overcast For the next few items, it may be helpful to utilize this resource of frontal symbols from the DataStreme website User s Guide or At map time, a bold blue line with triangles was found across western Pennsylvania, extending southwest through Tennessee and Oklahoma. These symbols indicated the position of a front. a. cold b. warm c. stationary d. occluded 13. The frontal boundary curving outward to the east and south from the strong Low Pressure in Ontario, Canada, has both purple semicircles and triangles on the same side of the boundary, which identifies this as a(an) front. a. cold b. warm c. stationary d. occluded 14. Irregular light blue, green, yellow, and red shadings scattered across the map (in locations including West Virginia and western Pennsylvania and just across the U.S.-Canadian border into the province of Alberta) indicated where the national network of weather radars detected precipitation. The radar shadings showing the most intense precipitation at map time were generally located. a. near the center of the major High pressure b. near regions of lower pressure and along frontal boundaries

7 CWS 2-7 SP19 Suggestions for further activities: Displaying or following a sequence of recent surface weather maps ending with the current map can show the movement of weather makers (high and lowpressure centers and fronts) and the changes in atmospheric conditions at your location over time resulting from their movements. Practice looking for connections between these weather changes depicted by the map sequence. Noting such connections allows one to make general predictions of local weather for the next half day or so. Weather & GIS Geographic Information Systems (GIS) is a framework designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. The key word to this technology is Geography, which means that some underlying segment of the data is spatial (in other words, data that are in some way referenced to locations on Earth). GIS is an investigative technique that can be applied to many disciplines; in our case, besides the traditional weather instrument observations (e.g., thermometer, rain gauge), GIS techniques can be used to monitor changes in terrestrial, atmospheric, and aquatic systems that result from a changing climate. ArcGIS is a GIS software application for examining maps and analyzing geographic data. The software can be used to create maps, compare data, analyze mapped information, share and discover geographic information, and a whole range of other applications. Esri is an international supplier of GIS software, web GIS, and geodatabase management applications. In this study, you will be using ArcGIS Online from Esri to interrogate past, present, and future weather data. Please revisit the introductory module from Esri, titled Teaching with GIS (noted at the conclusion of Current Weather Studies 1), if you need help maneuvering around the GIS platform in this study. Open and Analyze Real-Time Weather Map Using real-time weather feeds from National Oceanic and Atmospheric Administration (NOAA), the following set of inquiries introduces a means by which to acquire information related to atmospheric pressure, temperature, wind speed, and wind direction. The maps will ultimately help you classify data, utilize weather-mapping symbols, and interpret patterns. To begin, follow this link in the ArcGIS online platform: This is the Real Time Weather Map Starting Point. On the left side of the screen, click on Content. Here you will see the layers of your map. Layers are the mechanism used to display a specific geographic variable in the overall database. In ArcGIS, layers are displayed in a particular order. Layers shown at the bottom of the map (near the surface of the map) are displayed first and then more layers are digitally placed on top of that initial layer. The Content listing on the left-hand side controls the ordering of layers. You may click and drag layers to change their ordering. As an analogy here to older technology, transparencies could serve as a layer in their use with an overhead projector to help visualize the complexity of multiple dimensions in data displays. Depending on transparency (or layer) order, only specific information is conveyed to the

8 CWS 2-8 SP19 user/viewer. In the case of GIS, your map can contain multiple layers, which are easily changeable. Some example weather variables that can be used as a layer are: pressure, wind speed, wind direction, cloud cover, radar, satellite imagery, and other data from a live NOAA feed. Your near real-time map and the list of associated layers should look something like that shown in Figure 3. Figure 3. Example of Real Time Weather Map Starting Point from ArcGIS Online. Note that Figure 3 was only captured at the moment of this module s creation, so your radar data layer will differ from that of Figure 3. If you do not see any radar data, check the box for Recent Weather Radar Imagery, located within the Content tab, to view that layer. You can experiment with the different layers by clicking the checkbox next to each variable title. You may also explore a different basemap. A topographic map is currently being displayed (as seen as the bottom layer and last item listed within the content tab). To change the basemap, click on Basemap, which is located above the Content tab. A few other dropdown options appear, including Topographic, Imagery, and Streets. These are just a few variations of ways to view maps in the ArcGIS Online platform. For this exercise, keep your map set to Topographic, because this is best to view large-scale weather patterns. Focus on the Pressure Layer We will now explore surface air pressure patterns across the U.S. and locate areas of high and low pressure. First, turn on the Current Pressure Mb layer by checking the box next to it. Click on the text Current Pressure Mb to reveal the drop down options of Stations and Buoys. You can also click the small triangle to the left of Current Pressure Mb to see the drop down options. Ensure that the Stations box is selected. Hovering over Stations reveals additional options for this layer. The first symbol displays the legend of the data.

9 CWS 2-9 SP19 The second symbol displays the actual raw data in a table/chart format below the map. The third symbol your map. allows you to change the style of the symbol used to display the data on The fourth figure is a search tool to help filter your data. 15. Click on the Show Legend option, within the Stations drop down, and view the range of pressure values and their color coding. When you click this tab, the GIS software is querying all the available weather stations, extracting just the pressure observations, and categorizing them all into a digestible scheme for you to view. Imagine if you had to do this by hand! Given the categories displayed for you here, generally what shade of colors are associated with higher values of pressure? a. light colors b. dark colors 16. Next, click on a station dot in the actual map area on the right side of the display (any dot will do). You may want to zoom into the map area a bit to distinguish between individual station boxes (zooming may be done by either clicking the + or - symbols in the upper left-hand corner of the map or by scrolling your mouse wheel). This dot represents the location of a weather station that is sharing its observations with NOAA. When clicked, a new box should pop up with information related to its specific location. What type(s) of information is(are) included? a. station name b. temperature and humidity c. wind direction and speed d. sky conditions and visibility e. all of the above are correct By analyzing the pressure values reported on weather maps, you can find specific patterns, and locate the centers of locally highest and lowest pressures. We will see that these pressure centers often mark the midpoints of major weather systems; either regions of fair weather or stormy conditions, respectively. Let s create a new layer with High and Low pressure. In the very upper right hand corner of your screen click Modify Map. Now, in the left hand corner of you screen find the Add button (next to Details ) and click on it. Scroll down to Add Map Notes and name your map notes layer H and L Pressure.

10 CWS 2-10 SP19 Keep the template set at Map Notes. Click the Create button. You will then see a new screen populate that provides you options to add text graphics to your map. Figure 4 is an example of what your screen will look like at the conclusion of these steps. At this point you should be able to add Hs and Ls to our map, similar to what was done from the data in Figure 2. In this case, however, you are the analyst. GIS will simply aid in your interrogation of the data, conveniently plotted by the underlying software. Denoting areas of High and Low pressure will provide a greater frame of reference to the data and allow for the overall weather patterns to become more evident. Figure 4. Example of the features options associated with new H and L Pressure layer.

11 CWS 2-11 SP19 Reference your answer from Item 15, where you identified which color shading was related to higher pressure. Next, label your pressure systems on the map by Selecting Text under H and L Pressure - Text. Then, click on your map and type H where you think a high pressure system is centered, based on your observations of the pressure layer and your answer to Item 15. Click on the map outside of the text box in order to reset the settings. Click on the H and grab the edges (corner) of the symbol to make the text larger as shown in Figure 5. Repeat the process until you ve labeled all of the highs and lows on the map. When you are done click on the map screen and then click on Details on the left side of your screen to get out of the labeling layer. Figure 5. Example result of how Highs and Lows can be added to the H and L Pressure layer. Note: This is a near real-time map. Your areas of high and low pressure will differ from that shown here because the time you engage this module will be different then when it was created. GIS is a powerful tool for most datasets that can be mapped. As you might imagine, it can be used for both Ocean and Climate applications as well. You are encouraged to toggle on/off various features of the platform at this point to explore other ways you can utilize these tools. Recognize that you cannot break anything, so take a deep-dive into the data turning on/off various layers or changing their transparency. In Current Weather Studies 3, we will next turn our attention to the Weather Satellite Imagery layer. Copyright 2019, American Meteorological Society