METR 361                                                                                      Spring, 2017

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). Answer all parts of all four questions in the blue books except for the maps in questions 2 and 3. If you like, you may instead send me your answers in a text, Word, or Open Office (.odt) file. 

 

1. For this question, open the PowerPoint showing the NAM 1000-500 mb thickness/MSLP forecast out to 84 hours, starting at 00Z on an unspecified date.

       a. ( 6%) The storm that affects the northeast U.S. in the first 48 hours doesn’t seem to fit any of our three types.  If you had to pick one type and only one, how would you classify this storm?  Briefly explain why you picked your answer.

       b. ( 5%) Starting from the 24 hour forecast, is this an “Atlantic Bomb”?  State your reasoning, being as quantitative as you can.

       c. ( 4%) Based only on this guidance, how much precipitation (liquid equivalent) would you forecast to fall at New York City in the whole period? 

d. ( 4%)What type(s) of precipitation will fall at New York City?

       e. ( 4%) Based only on this guidance, how much precipitation (liquid equivalent) would you forecast to fall at Boston in the whole period? 

f. ( 4%) What type(s) of precipitation will fall at Boston?

       g. ( 8%) Toward the end of the forecast, another storm approaches the northeast U.S.  What type of storm is that one? Again, explain your choice using more than one characteristic of the storm..

 

2. This question is about the 250 mb map from 00Z on an unspecified date.  While they are not labeled, the color-filled contours are isotachs, every 20 knots.  The first one starts at 70 knots.  You also have a paper copy of this map.

       a. ( 12%) On the paper copy, draw arrows showing both the geostrophic wind vector and the ageostrophic wind vector at the points marked A and B.  Do not draw arrows anywhere else.

       b. ( 7%) What effect will the jet stream marked C have on the jets marked A and B?  As always, briefly explain your reasoning (Hint: the jet streak of C appears to be ~185 knots and is coming from the west.

 

3. For this question, refer to the PowerPoint showing NAM 500 mb/vorticity contours and colors.  You have been given 00Z and 12Z on Day 1 and Day 2.  You also have a surface map of 12Z on Day 2 and a paper U.S. base map. 

a. ( 12%) On that blank U.S. map, draw the 500 mb height contours that you should expect to be on the map for 00Z on Day 3, i.e., 12 hours after the last color map. 

b. ( 6%) The surface map at 12Z on Day 2 shows a surface circulation. There was a cyclogenesis but why is it in the middle of Nevada?  Describe the mechanism that caused the surface Low to be there.

c. ( 6%) Select one major U.S. city from this map of major U.S. cities that will be impacted by the upper air pattern shown in the eastern U.S. on Day 1.  Identify your city and give their residents a weather outlook for Day 1, based on the 500 mb maps shown in the PowerPoint.  This is not a detailed forecast, just an outlook of the expected surface conditions. 

d. ( 10%) What is your outlook for southern California during days 1 and 2, just based on the NAM 500 mb forecast shown?  

 

4. Get a NAM forecast, initialized at 12Z today, Feb 22, 2017.  Use any forecast maps from that package to create a forecast.  Do not use any other forecast of any kind but you may use any map from the NAM package.

 ( 12%) There will be a Colorado Hooker storm during this period. Make a WxChallenge-style forecast for Denver, Colorado (KDEN) for the 24 hours from 06Z Thursday Feb 23 to 06Z Friday Feb 24.  I will verify it from the National Weather Service daily climate report.  Forecast all four parameters required by WxChallenge, max temperature, min temperature, highest wind speed, and total liquid-equivalent precipitation.  Total error points of 12 or less get all 12%.  Total error points of 24 or more get 0%.  Other scores in between 12 and 24 will score proportionally, e.g., 18 error points gets you 6%. Come up with four numbers, based on the NAM guidance maps only (No MOS, no NWS, no USL, even if you know where to find them).  You may check the current Denver observations.