METEOROLOGY 361                                                                                                                Spring, 2007

Exam 2                                                   

 

 

Directions:  Answer all parts of all 6 questions in the blue books or in a Notepad or Word document to be left on your desktop.  Exception:  you need to draw on the map for question 2.

 

 You may use any notes and link to any Internet site.  You may NOT talk to anyone else.  If you have a question, ask me.  Your deadline is 4 p.m.

 

 

1. For this question, examine the sounding for Corpus Christi, TX (CRP) on April 10, 2004.  This looks like a classic tornado sounding.  The indices are all favorable and elements of the optimum pre-storm environment as we discussed in class are present.  The SPC severe storm reports show that severe weather did occur, but it was mostly hail, some very large.  However, NO tornadoes occurred, not a single one.

             ( 6%) What was missing or unfavorable at CRP at 12Z on April 10, 2004 such that tornadoes did not occur?  You may also want to view the 12Z surface, 850 mb, 700 mb, 300 mb, and 200 mb analyses.


 

2. Here's a situation that occurred on March 30, 2005.  You are given the 12Z surface map, 850 hmb, 700 mb, 300 mb, and 200 mb analyses.  You may also view the NAM 12 hour forecast of SLP, 850 mb, 700 mb, 300 mb, and 200 mb maps.

 

        a. ( 10%) On the blank U.S. base map provided with this exam, draw a convective outlook using the conventional symbols.   This requires you to assess the potential for severe weather and its projected location.  IMPORTANT:  Your convective  outlook is for 12Z to 00Z only.  Don't include severe weather to occur after 00Z.

        b. ( 20%) In the blue books or in your Notepad or Word files, briefly explain your reasoning, using specific examples from the maps.

3. On March 27, 2007 you forecasted severe weather.  The convective outlook didn't predict any organized areas at risk for severe thunderstorms but the verification showed 71 severe events scattered from west to east coasts.  


         (24%) Now that we know what happened, explain why severe thunderstorms occurred in four areas:  

                1. California

                2. Wyoming

                3. the area where Texas, Louisiana, and Arkansas meet

                4. the swath from Michigan to North Carolina.


For your answers, you could refer to features of the 12Z and 00Z surface maps, 12Z and 00Z 850 mb maps, 12Z and 00Z 700 mb maps, 12Z and 00Z 500 mb maps, 12Z and 00Z 300 mb maps, and/or 12Z and 00Z 200 mb maps.  You do NOT need to find something on each map.  In fact, if there were favorable features on every map, the convective outlook would have had a higher risk of severe weather.  But something must have been there so find it for each area.  There may be more than one favorable feature in an area.  Remember to use both 12Z and 00Z maps.

4. The next day we forecasted severe weather, March 28, there were 298 reports so it was a much more active day, concentrated in the western High Plains.  There were a large number of tornadic storms in the panhandle of Texas, around Amarillo (AMA) and in western Kansas, near Dodge City (DDC).  

             a. ( 6%) The 12Z sounding at AMA for March 28 showed some favorable factors for severe weather.  So did the 12Z OUN sounding.  The differences in these two soundings were fairly minor yet severe thunderstorms occurred at AMA but not at OUN.  These stations are close to each other (marked on the severe report map).   The 00Z March 29 soundings for AMA and OUN were quite different, however.  What happened at AMA but DIDN'T happen at OUN by 00Z that would explain the lack of severe weather at OUN?

            b. ( 10%) This link will take you to a text listing of the sounding at DDC at 00Z March 29.  Use the information to determine the Severe Weather Threat Index (SWEAT) and the Total-Totals Index (TTI).  Show all work in your calculations.  (you may want to review the Index lab)

            c. ( 4%) Assess the SWEAT and TTI from part b.  Do they indicate poor, fair, good, or spectacular prospects for severe weather? (Pick one for each index)

5. For this question you must run the BUFKIT program on your desktop.  Choose the GFS3 model data for South Bend, IN (KSBN).                      

            a. ( 4%) What is the most likely time and date when freezing rain will fall, according to BUFKIT?

            b. ( 6%) What is BUFKIT showing you that would cause you to make a forecast of freezing rain?

 


6.  On April 4, 2003 there was an ice storm across the breadth of northern New York.  Click here for the 12Z U.S. surface, northeast station plot, and 850 mb map.  You also could view the Eta (now the NAM but still called the Eta in 2003) surface.

 

Two days prior to April 4, the forecasts were not for freezing precipitation types in northern New York State.  Those forecasters were looking at maps such as the Eta 48 hour surface forecast and the Eta 48 hour 300 mb forecast.  Both are supposed to verify at 12Z on April 4.  Also, here is an 850 hPa forecast loop which includes 12Z on April 4.

 

        a. ( 5%) What verified on the 12Z April 4 surface map that was different from the 48 hour forecast and would help to explain freezing precipitation in central New York where none was forecasted?

 

        b. ( 5%) What verified on the 12Z April 4 850 mb map that was different from the 48 hour forecast and would help to explain freezing precipitation in central New York where none was forecasted?