Fall 2023 - Weather Mapping Assignment (1)
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LAB 7: WEATHER MAPPING
100 points
Due at the beginning of lab next week.
LEARNING OUTCOMES
At the end of this lab, you will be able to:
1.
Understand the components of a weather “station model.”
2.
Decode station model features.
3.
Analyze weather maps and interpret current and future conditions for a location.
INTRODUCTION
The station model is a graphic means of conveying measured meteorological information in compact form on a map. The
station model includes information about temperature, wind direction and speed, atmospheric pressure, dew point, precipitation,
and cloud cover. Information for decoding a simplified version is presented below (Figure 1).
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Figure 1 Decoded station model. Image from Wikipedia.
Some of the information in the station model is encoded. This is the case with pressure, wind direction and speed,
precipitation, and cloud cover.
Pressure is always given in millibars (mb), but the first digit (normally a 9 or 10) is left off. To decode the pressure value, look
at the first number. If the first number is a 5 through 9 inclusive, then add a 9 to the front. If the first number is a 0 through 4
inclusive, then add a 10 to the front. The very last digit on the right is in the tenths place (on the right side of the decimal point).
This method for decoding air pressure given on the station model works most of the time. However, there are times when this
method will break down, as some of the strongest hurricanes, for example, have had air pressure readings below 900 mb. The station
model also contains information on pressure tendency and change over the last 3 hours. Pressure change is given in tenths of
2
millibars over 3 hours (Figure 2: Barometric Tendency).
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Figure 2. Weather station symbols. Image from https://www.nj.gov/dep/seeds/wssym.htm.
Another piece of information given on the station model that needs to be decoded is cloud cover (Figure 2: Cloud Coverage).
Each station model locates the individual station (observation point) with a circle. The circle itself indicates the degree of cloud cover.
In general, the more the circle is filled in, the more cloud cover there is.
A meteorological image known as a wind barb is used to describe wind direction and speed on the station model (Figure 2:
Wind Direction). This method uses the circle as a compass with north at the top. The wind barb is a line with flag(s) on one end like
an arrow with feathers on one end). In meteorology, the wind is always identified by the direction in which it is coming from (a south
wind comes from the south and blows toward the north). The wind speed is dependent on how many flags there are (Figure 2: Wind
Speed and Figure 3). In general, the more flags, the faster the wind is blowing.
Figure 3. Diagram showing how wind speed is plotted. It is plotted in increments of 5 knots, with the outer end of the symbol facing towards the direction the wind is
blowing. Figure from https://www.wpc.ncep.noaa.gov/html/stationplot_printer.html.
A final element encoded on the basic station model is present weather/precipitation. These are encoded in the form of
weather symbols (Figure 2: Weather Conditions, Showers, and Misc. Sky Cover).
Station models for each weather reporting site are placed on a weather map. You are provided with two surface weather
maps for the U.S. from 17 October 2023 and 18 October 2023 (Figures 4/5/6/7 and Figure 8). Meteorologists will analyze these
surface weather maps to find the different fronts, locate areas of atmospheric moisture, locate high pressure and low-pressure areas,
and other meteorological factors. There are four different types of fronts, which are boundaries that separate contrasting air masses.
Cold fronts replace warm air with cold air and are denoted as lines (blue color if colored) with triangles pointing in the direction the
front is moving. Warm fronts replace cold air with warm air and are denoted as lines (red color if colored) with semicircles extending
in the direction the front is moving. Another type of front is a stationary front. It has little movement associated with it (hence, the
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name stationary), and is denotes as a line (alternating blue and red color, if colored) with alternating triangles and semicircles on
opposite sides of the boundary (looks like a warm front-cold front mix). Finally, there is the occluded front, which comes in one of
two types. A cold type is where the occluded front replaces cool air with cold air. A warm type is where the occluded front replaces
cold air with cool air. In addition to fronts, meteorologists look for other boundaries, such as the dryline. Just as the name suggests, it
is a boundary between moist air to the east and dry air to the west.
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Figure 4. Isobars. 6 pm CDT October 17 2023
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Figure 5. Isodrosotherms. 6 pm CDT October 17 2023
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Figure 6. Isotherms. 6 pm CDT October 17 2023
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Figure 7. 6 pm CDT October 17 2023
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Figure 8. 6 PM CDT 18 October 2023
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LAB 10: WEATHER MAPPING
Take measurements, perform the following calculations, and answer the questions
[100 pts]
.
1.
Decode the requested information from each of the following station models
[25 points)
:
Barometric Pressure: 024
Temperature: 37
Dew-Point Temperature: 21
Barometric Pressure: 998
Temperature: 63
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Dew-Point Temperature: 60
Sky Coverage: 1/2
Current Weather: Thunderstorm
Barometric Pressure: 117
Temperature: 43
Dew-Point Temperature: 20
Sky Coverage: No clouds
Wind Speed: 15 Knots
Wind Direction: SW
Pressure Change during last 3 hours: Rising Steadily
Pressure Tendency: 17
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Barometric Pressure: 997
Temperature: 27
Dew-Point Temperature: 25
Sky Coverage: Fully Cloudy
Wind Speed: 25 Knots
Wind Direction: NW
Pressure Change during last 3 hours: Falling Steadily
Pressure Tendency: 11
Part II: Mapping Isolines
Use draw tools on your laptop, or draw on the printout to create a completed isoline map on Figure 8. Be sure to include a color-coded key.
Compare differences in isotherms and isobars between the maps.
2.
Figures 8 already has pressure analyzed plotted with isobars (lines of equal pressure). Draw isotherms (lines of equal
temperature) for 60°F and 70°F on Figure 8 and compare them between the two maps.
(5 pts.)
✅
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3.
Explain the changes you see in the position of the isotherm between the two maps. What would cause this/these change(s)? (Pay
attention to the time change)
(5 pts.)
I think what caused these changes is a cold front occurring around 24 hours before.
4.
Plot the 20°F, 30°F, and 40°F isodrosotherms (lines of equal dew point) on Figure 8 (there will be more than one contour line for
the 30°F and 40°F isodrosotherms). Use a different color for these than the color you used for the isotherms (lines of equal
temperature)
(5 pts.)
✅
5.
Look at the entire 30 and <20°F isodrosotherms. Did the area of <20°F dew points increase or decrease between Tuesday at 6 pm
CDT (Figure 5, Figure 7) and Wednesday 6 pm CDT (Figure 8)?
(5 pts.)
Increase
6.
Locate and plot two drylines with a dotted line on Figures 8. (Hint: look for a sharp change in dew points i.e., a gradient)
(5
pts.)
✅
7.
Locate and plot two warm fronts on Figure 8. (Look for areas where the wind is blowing from a warmer to a cooler area and draw
the fronts along these approximate boundaries using the correct symbology. Use red for this if you can, but the symbology is
more important).
(5 pts.)
✅
8.
Locate and plot the cold front on Figure 8 (Look for areas where the wind is broadly blowing cooler air into areas with warmer
air). Use blue if possible and be sure to use the correct symbology.
(5 pts.)
✅
9.
Locate and plot the high-pressure system on Figure 8 (Look for areas where the pressure is higher than any area around it). Be
sure to use the correct symbology.
(5 pts.)
✅
10.
Locate and plot the low-pressure system on Figure 8 (Look for areas where the pressure is lower than any area around it). Be sure
to use the correct symbology.
(5 pts.)
✅
11.
What direction has the low-pressure system moved between Tuesday at 6 pm CDT (Figure 4) and Wednesday at 6 pm CDT (Figure
8)?
(5 pts.)
Up or North
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12.
Given what you have analyzed so far, what weather would you expect in western Wyoming over the next few days? Why?
(5 pts.)
I would expect to see cold breezy weather because the cold front has swept through.
13.
What kind of weather would you expect to see in Detroit, Michigan on Thursday? Why?
I think the weather would be moist and humid because the warm weather is moving North.
For the remainder of the lab, use the
NOAA Jet Stream
website to answer the following questions. Read the introductory slides to
understand the meaning of the different layers and how to interact with the maps.
14.
Using the 200 mb map (on the right side, click Upper Air Charts), observe the pattern of the jet stream (with wind barbs) and the
wind contours for North America. Where would the windiest parts of the country be on average throughout the year according to
the 200 mb map? Why?
(5 pts.)
I’d say Oregon, California, Nevada, and Washington. Because the darkest blue in the wind contour is there.
15.
Using the 500 mb map, what is the geopotential height above northwest Arkansas? Be sure to give the height in meters (see the
height contours paragraph)
(5 pts.)
570 meters
16.
What is the wind speed over NW Arkansas at 500 mb?
(5 pts.)
50 Knots
17.
Finally, navigate to the 850 mb map and turn on the “Precipitable Water” (PW) layer. Which part of the country should be most
concerned about heavy rains and flooding according to this weather pattern? Why?
(5 pts.)
East Texas because it’s green and
green represents 38mm or greater of precipitation.
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