Lab 7 Weather Mapping New
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LAB 11: WEATHER MAPPING 100 points
Due one week from lab start time.
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).
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. 1
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 millibars over 3 hours (Figure 2: Barometric Tendency).
Figure 2. Weather station symbols. Image from https://www.nj.gov/dep/seeds/wssym.htm.
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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).
Meteorologists will analyze these station models on 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 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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LAB 11: WEATHER MAPPING Name: _____________________________
Section: _____________________________
Take measurements, perform the following calculations, and answer the questions [100 pts]
.
1.
Decode the requested information from each of the following station models [22 points]
:
Barometric Pressure: Temperature: Dew-Point Temperature: Barometric Pressure:
Temperature:
Dew-Point Temperature:
Sky Coverage:
Current Weather:
4
Barometric Pressure:
Temperature:
Dew-Point Temperature:
Sky Coverage:
Wind Speed:
Wind Direction:
Pressure Change during last 3 hours:
Pressure Tendency:
Barometric Pressure:
Temperature:
Dew-Point Temperature:
Sky Coverage:
Wind Speed:
Wind Direction:
5
Pressure Change during last 3 hours:
Pressure Tendency:
Part II: Analyzing Surface Maps
Use the figures to answer the following questions.
Figure 3. Surface analysis map on April 29th, 2022. Retrieved from
https://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php
2.
What is causing calm, clear weather in the northeast part of the country (Washington, Oregon, Idaho etc.)? [5 pts]
3.
What is the pressure in millibars at the center of the High off the coast of North Carolina? [3 pts]
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4.
What kind of weather would you expect in this area? [5 pts]
Part III: Upper Air Meteorology
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.
5.
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]
6.
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]
7.
What is the wind speed over NW Arkansas at 500 mb? [5 pts]
8.
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]
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