CWS 2A

DataStr= eme Atmosphere Current Weather Studies 2A:

SURFACE WEATHER MAPS

Do Now:

Print this file.
Print the Monday Current Weather Studies Ima= ge 1 and Image 2 Files.
When available, answer the two "Concept of the Day" questions in the Tuesday, 15 Septem= ber 2009, Daily Weather Summary File.

To Complete Investigation:

Read Chapter 2 in the DataStreme Atmosphere textbook and respond to the Chapter Progress Questions in the DataStreme Atmosphere Study Guide Investigations binder. [Do not complete the Questions for Review and Critical Thinking Questions appearing in the = Weather Studies Investigations Manual].
Complete the introductory portion of Investigation 2A in the Weather Studies Investigations Manual, which ends when you reach the statement, "As direc= ted by your course instructor, complete this investigation by either: ---<= /b>." [Do not complete the Applications portion of the Investigation.= ]

Continue with this Mon= day - CWS A (Current Weather Studies A) from the course website to complete this investigation.

The Monday Daily Weather Summary for 14 September 2009 briefly describes= the weather across the contiguous United States. Much of the northeast and north central portions of the country were experiencing fair weather while the So= uth and West had extensive cloud cover and precipitation at many locations. The details of these conditions are given at specific stations in a coded stati= on model.

3= .      Image 1 is the "U= .S. - Data" map for Sunday evening, 00Z 14 SEP 2009 (8 PM EDT, 7 PM CDT, 6= PM MDT, 5 PM PDT). The Image 1 map shows selected weather data plotted about circles that represent the location of stations using the coded surface sta= tion model. Observe the station model for Oklahoma City, Oklahoma.= The station model shows a temperature of [(72)(68)(59)] degrees F, and a dewpoint of 64 degrees F.

4= .      The winds at Oklahoma City were generally from the [(northeast)(southeast)(southwest)(northw= est)] at about 10 knots (one long "feather" on the shaft).

5= .      The coded pressure value was plotted as "132", meaning the act= ual atmospheric pressure corrected to sea level was [(13.2)(132.0)(1013.2)(113= 2.0)] mb.

6= .      The sky cover (amount of shading inside the station circle) indicated [(<= u>clear)(partly cloudy)(overcast)= ] conditions existed at map time.

7= . Wind speeds across the south central region showed a variety of station model notations for different speeds. Midland, <= st1:State w:st=3D"on">TX had one long and one short feather for 15 knots = while Wichita, in Kansas to the north, had one short feather for 5 knots. El P= aso in far western Texas had a circle around the station circle to denote a wind speed reported as <= b>[(calm)(25 knots)(50 knots)]= .

8= . At the "9 o'clock" position alongside the station circle, a weather symbol may be plotted to show present weather conditions. Oklahoma City shows two dots that signi= fy [(light rain)(light snow)(ha= ze)(fog)] was occurring. Arcata in northern coastal California also had two dots. For a li= sting of the frequently occurring weather symbols, see the User's Guide li= nked from the course website or go to http://www.hpc= .ncep.noaa.gov/html/stationplot.shtml.

9= . Some other stations are reporting various significant weather conditions. The weather symbol at Little Rock<= /st1:City>, Arkansas was two horizontal lines. This symbol indicated that Little Rock was experiencing [(rain)(fog)(haze)].

1= 0. The f= igure "8" on its side at Denver, in ea= stern Colorado, meant = [(rain)(fog)(haze)] was pres= ent there.

1= 1. Image 2 is the "Isobars, Fronts, Radar, & Data" map for Sunday evening, 00Z 14 SEP 2009, the same time as the U.S. - Data map. This map additionally shows the position of high-pressure centers and low-pressure centers with fronts as analyzed by meteorologists at NOAA's National Centers for Environmental Prediction. Colored shadings further denote where the national network of weather radars had detected precipitation. Radar reflectivities are related to precipitation intensiti= es according to the color scale along the left margin of the map area. (Genera= lly, the greater the reflectivity the greater the intensity of precipitation.)

The coded station pressure reports were used = to draw a computer analysis of the pressure pattern similar to the one you did= in Current Weather Study 1A. The center of relatively [(low)(high)] pressure was shown in southeastern Texas.

1= 2. In the broad area of precipitation surrounding the southeastern Texas pressure system, the individual station sky cover symbols [(are)(are not)] mostly cloudy to overcast in the region.

1= 3. The w= ind directions at the stations about the L in southeastern Texas were generally [(counte= rclockwise and inward)(clockwise and outward<= /u>)], consistent with the hand-twist model of a Low.

1= 4. The w= ind directions at the stations about a high-pressure area centered from southeastern Minnesota to southwestern <= st1:State w:st=3D"on">Michigan were ge= nerally [(counterclockwise and inward)(clockwise and outward<= /u>)], consistent with the hand-twist model of a High.

1= 5. One h= eavy line with triangles (blue on-screen) from northeast of Maine southwestward along the coast and into Pennsylvania marked the position of a [(cold)(warm)(stationary)] front. This front was the leading edge of slightly cooler air that was advancing across New England. This type = front also extended from the Low in southeastern Texas into the western Gulf of Mexico.

1= 6. A sho= rt heavy line with half-circles (red) designated a [(cold)(warm)(stationary)] f= ront that extended to the east from the Texas Low to southeastern Louisiana.

1= 7. From eastern Louisiana across Florida and into the Atlantic the frontal system= was shown with alternating blue triangles and red semicircles on opposite si= des designating this portion of the frontal system to be a [(cold<= /i>)(occluded)(stationary)] front.

Additionally, dashed orange lines on the map signify low-pressure troughs, extensions of lower pressure, sometimes marki= ng the positions of dissipated or forming fronts. And a short arc of purple alternating semicircles and triangles marks an occluded front that joins the Low off the California-Oregon border to the northern end of a cold front. T= hose fronts are approaching the coast.

For more practice on deciphering station models and map symbols, go to http://profhorn.aos.wisc.edu/wxwise/AckermanKnox/chap1/decoding_= surface.html.

Displaying a sequence of recent surface weather maps ending with the cur= rent map in your classroom can show the movement of "weather makers" (= high and low pressure centers and fronts) and the changes in atmospheric conditi= ons at your location over time resulting from their movements. Practice looking for connections between weather changes depicted on the map sequence and predict local weather for the next half day or so.

You can also observe how station model conditions change as weather syst= ems pass across a region by going to the NWS Surface Analysis link on the course website. The link takes you to the NWS' Hydrometeorological Prediction Center site. Scrolling down allows you to "Create a Surface Analysis Loop&quo= t; for various regions. The United States choice, then clicking "Display Loop" will show an animation of the latest day's series = of 3-hourly station models along with fronts and Highs and Lows.

Place the answers to Current Weather Studies activities 2A and 2B on the= CWS Answer Form (provided from the DataStreme Atmos= phere website on Wednesdays).

Return to <= span class=3DSpellE>DataStreme Atmosphere website

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