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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

2018-2019 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

http://www.wpc.ncep.noaa.gov/html/stationplot.shtml.

For a more exhaustive set of 100 possible weather symbols which can be used in station models,

go the NWS JetStream Max site at:

https://www.weather.gov/jetstream/sfc_plot_symbols_max#ww

Some of the items in this Current Study refer to symbols on this specific list.

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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 2019. 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

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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

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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.

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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. -31

7. Further to the east from North Dakota, the dewpoint temperature at Minneapolis, Minnesota

was ________ degrees F.

a. -18

b. -28

c. -35

d. -42

8. 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

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10. The coded pressure value at Minneapolis was plotted as “282”, meaning the actual

atmospheric pressure corrected to sea level was ________ mb.

a. 28.2

b. 282.0

c. 928.2

d. 1028.2

11. 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 http://www.wpc.ncep.noaa.gov/html/fntcodes2.shtml.

12. 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

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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 low-

pressure 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 https://www.arcgis.com/home/index.html 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: http://arcg.is/Oir1j. 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

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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 drop-

down 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.

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The second symbol displays the actual raw data in a table/chart format below the map.

The third symbol allows you to change the style of the symbol used to display the data on

your map.

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.

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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.

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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