METR 361                                                                                                                  Spring, 2019

Exam 1                                                

 

Directions: This is an Open-notes exam.  Use anything you want, including the Internet.  You can’t ask each other questions but you can ask me for clarifications (no guarantee that I’ll be able to answer). You have 90 minutes to complete this exam.  Answer all parts of all questions in the blue books or write a txt or odt file and send to Jerome.Blechman@oneonta.edu.

 

 

1. Earlier this month, a Colorado storm formed in the usual area and moved into the Midwest to affect millions of people.  Using PowerPoint loops of the maps forecast by the NAM at 00Z on Feb 3, answer the following questions.  You are given the forecast loops of MSLP/1000-500 mb Thickness, 850 mb heights/RH, 700 mb heights/RH/Vertical Velocity, 500 mb heights/vorticity, 300 mb/isotachs, 250 mb/isotachs, and 200 mb/isotachs. Only the first 60 hours of the 84 hour NAM are shown.  Assume the NAM forecasts are accurate.

 

            a. ( 6%) During Feb 3 and 4 over the Pacific Northwest coast, heights at the 250 mb level decrease and a cutoff low forms.  Using just the 250 mb loop, explain that behavior.   .

            b. ( 6%)  Colorado storms require a warm conveyor belt to produce heavy precipitation.  Based on the NAM forecast, will there be a strong warm conveyor belt?  Why or why not?  Do not simply say the forecast says so.

            c. ( 5%) Was this a major snowstorm for Denver like the ones we studied in lecture? Yes or no? Justify your answer. This requires more than one loop so be sure to identify which ones you are using.

            d. ( 12%) We began forecasting for Duluth just as this forecast period ended. Suppose we had been forecasting one day earlier. What is your forecast for Duluth (KDLH) for the calendar day February 4 (06Z Feb 4 through 06Z Feb 5)? Provide all four of the usual numbers, i.e, max temperature, min temperature, max wind speed, and total precipitation.  Do not explain how you decided on your numbers, just list them.  Be as accurate as you can.

 

2. This is a BUFKIT question.  Since we can’t assume everyone can run BUFKIT on their personal machines (i.e., Macs),you have been given a PowerPoint loop of BUFKIT screenshots for Charleston, SC (KCHS). This is the 12Z run of the NAM from Feb 8.  Use only the information you can get from the PowerPoint.

            a. ( 6%) On the first image, the surface temperature is 3.6 degrees colder than it is 41 mb further up in the atmosphere.  What is the most likely reason for that surface inversion? Please describe briefly the information shown by BUFKIT that led to your answer.

b. ( 6%) KCHS experienced a cold front passage.  At what time(s) and date(s) did the cold front itself pass the station?  Don’t explain (yet).

c. ( 6%) Cite two BUFKIT parameters shown in the PowerPoint that support your cold frontal passage time(s) and date(s).  Briefly explain what it was about the behavior of those parameters that led you to believe that’s when the cold front passed through KCHS.

d. ( 8%) In the hours after the cold front passage, the 700 mb temperature barely changes but we know the air mass behind the cold front is building in, from what BUFKIT is telling us.  Briefly describe the changes that tell you about the air mass coming in.

 

3. For this question, focus on the 54 hour GFS forecast valid 18Z Monday Feb 11, 2019.  You have the following forecast maps: the MSLP/1000-500 mb thickness and the MSLP/2 m temperature/10 m wind.

        

             ( 12%) Draw the forecast positions of surface Highs and Lows anywhere on the map from the 54 hour forecast.  Add fronts using the proper symbols and in locations consistent with the provided guidance on the MSLP maps.

 

4. On Tuesday of last week our weather observing equipment reported unusual temperature behavior. The report from 3:45 a.m. to 9:55 a.m. on Feb 12 can be viewed as a text list with observations every five minutes. Normally, the temperature goes down until just before sunrise which that day was 7:01 a.m., after which it rises throughout the day.  But on Feb 12, 2019, the temperature stopped rising at 8:25 a.m., after which it fell more than 1°F. 

 

( 8%) Explain why the temperature fell from 8:25 to 9:55 a.m. on that day. Use the proper term that meteorologists call the phenomenon you are explaining.  If you don’t know that term, explain as much of the process as you can.  This is more than a one-sentence answer.

 

You may use as many of the following resources as you need: The text list, U.S. surface analysis for 12Z, northeast station map plot for 1407Z, northeast surface analysis for 12Z, Binghamton Radar image for 1302Z, Albany sounding for 12Z, and the Buffalo sounding for 12Z.

 

5. For this question you have analysis maps as follows: a PowerPoint loop of U.S. CONUS surface, and the 925 mb, 850 mb, 700 mb, 500 mb, and 250 mb maps, all from 12Z December 16, 2018.

            a. ( 6%) By 00Z December 17, 2018, a storm was located on the coast of the northeast U.S., near New York City but coastal cities did not report snow.  What was missing?

            b. ( 9%) Based on the maps shown, what would be the appropriate forecast for New York City (Central Park) for the period from 00Z December 16 to 00Z December 17?  Forecast the parameters the general public needs to know.

            c. ( 5%) Would a National Weather Service Office consider this storm to be a “bomb”?  Why or why not?

            d. ( 5%) In central Canada December 15-17, there is a storm shown on the surface map loop. It’s an Alberta Clipper.  Does this storm affect the CONUS in any way during the period of the surface loop? Explain.