METR 360                                                                                                         Fall, 2016

Exam 2                                                           

 

Directions:  Answer all parts of all questions in the blue books or write a text file which you may e-mail to Jerome.Blechman@oneonta.edu.  For calculations, show all work.  You may use any source, including your notes, any textbook or the Internet.  You may NOT talk during the exam, except to me.  Raise your hand if you have a question.

 

The following information may (or may not) be useful:

formulas

 

 

1. For this question, refer to the 12Z 500 hPa map. 

            a. ( 10%) You have a greyscale paper copy of the map.  Draw height contours using the standard contour interval, assuming perfectly geostrophic flow. Be sure you have the correct heights.  Label them properly. 

            b. ( 4%) Short answer:  The flow in the northern half of the central U.S. is most accurately described as

                                    A. Zonal     B. East to west     C. Cold advection     D. Meridional 

            c. ( 4%) Find the one station with a wind that is going in a direction that is exactly opposite to what the height contours require.  Circle it on the paper map and write the three-letter identifier in your blue book or text file. 

            d. ( 4%) On your paper map from part a, mark a trough and a ridge.  Write the words on the map in the proper places for those labels.

            e. ( 6%) Based on your answers to part d, where would you expect to find the surface High and Low?  Write the labels “High” and “Low” on the map.

            f. ( 6%) What would you expect of the movement for these surface features?

            g. ( 6%) The part of the map around New York State is expanded here. A fictional station identified NYX has been added.  What is the sign of the relative vorticity at NYX?  What is the sign of the absolute vorticity at NYX?  Do not show any calculations.

            h. (6%) Also at NYX, what weather would be expected from the vertical motion that would result solely from the absolute vorticity from part g?  Briefly explain.

 

 

2. This question is about the MOS guidance shown below:

 

KWOW   GFS MOS GUIDANCE     1200 UTC                      

 DT /OCT  12/OCT  13                /OCT  14                /OCT  15

 HR   18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 06 12

 N/X                    49          55          36          53    34

 TMP  59 60 56 53 51 51 51 52 53 51 46 43 40 38 37 44 49 50 45 38 36

 DPT  42 42 43 45 46 47 47 48 45 43 41 38 36 34 33 34 32 29 28 30 30

 CLD  CL CL CL BK CL SC OV OV OV OV CL CL CL FW FW CL CL CL CL CL CL

 WDR  19 18 18 18 18 18 19 21 28 31 32 33 33 33 33 01 35 35 02 10 15

 WSP  08 09 08 08 07 08 08 07 09 10 08 07 05 06 06 07 07 05 04 02 04

 P06         1     0     6    91    13     1    10     2     2  2  0

 P12                     7          91          10           5     5

 Q06         0     0     0     2     0     0     0     0     0  0  0

 Q12                     0           2           0           0     0

 T06      0/ 0  0/ 0  3/ 1  5/ 3  0/ 0  0/ 0  3/ 0  1/ 0  1/ 0  0/ 0

 T12            3/ 0        9/ 4        0/ 8        6/ 1     1/ 0   

 POZ   0  0  0  0  1  0  1  1  0  0  0  0  0  0  0  0  0  0  0  1  0

 POS   0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  4 16  0

 TYP   R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R

 SNW                     0                       0                 0

 CIG   8  8  8  8  8  8  4  2  2  4  8  8  8  8  8  8  8  8  8  8  8

 VIS   7  7  7  7  7  7  7  4  5  7  7  7  7  7  7  7  7  7  7  7  7

 OBV   N  N  N  N  N  N  N BR BR  N  N  N  N  N  N  N  N  N  N  N  N

    

 

The station KWOW exists but that’s not its real identifier of course. MOS was initialized at 1200 UTC on October 12.

 

 

            a. ( 6%) Assume this is a WxChallenge station so the forecast day goes from 06Z to 06Z.  You are forecasting on October 12 for the next day.  What is your forecast maximum and minimum temperatures from 06Z Oct 13 to 06Z Oct 14, based solely on this guidance?

            b. ( 4%) An obvious and significant meteorological event happens during your forecast period.  What is it?  Just name the event.

            c. ( 9%) Pick three forecast parameters that definitely identify your meteorological event from part b. At what time(s) are each of your three forecast parameters occurring on this guidance and how does each parameter uniquely point to the event you named in part b?

 

3. During the week of December 26, 2015 through  December 30, 2015, a series of waves can be seen on the 500 mb maps for that week. The maps are shown as a loop in PowerPoint format, each frame being a separate map.  If you are at a Linux computer, double-click it to run it in Open Office Presentation.

            a. ( 4%) At 00Z on Dec 26, 2015, a long wave trough was located in the southwest U.S.  It should be obvious from the loop that there is a short wave which exits the long wave trough.  By 00Z on Dec 29, three days later, the short wave trough is in northern Illinois after travelling 2400 km.  Calculate the wave speed directly from the distance travelled in 3 days (reminder:  there are 86400 seconds in each day). Show your work.   

            b. ( 8%) Using your wave speed from part a, and assuming the wave is at an average latitude of 40°N, and has a wavelength of 1000 km, what is the mean west-east wind required?   Show all work. 

            c. ( 5%) The mean west-east wind that you calculated in part b does not appear to be consistent with the map from 00Z December 26.  Assume you made no mistakes in part b and explain how U can be so different from what you seem to see on the map.

            d. ( 5%) The wave pattern at 00Z on December 30 looks very similar to the pattern at 00Z on December 26.  Offer a brief explanation based on the short and/or long wave movements. 

 

4. This is a question about lake effect.  You have a surface analysis map, a surface station plot map, the 850 mb map, and the GLSEA analysis.

 

            a. ( 8%) Suppose you are employed by a Great Lakes shipping company and need to alert drivers of lake effect snow (LES) on January 5.  Use the blank map provided to mark areas that drivers should avoid because of LES.  Also, mark the area where the LES would be heaviest.

            b. ( 5%) Briefly justify the areas you marked.  You are writing this justification to a meteorologist familiar with LES so you shouldn’t waste time explaining why it works. List the factors.  Be quantitative.