A World of Weather
Fundamentals of Meteorology

Laboratory Exercise #5

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First, read this background material on Model Ouput Statistics (meteorologists shorten this forecasting tool to MOS...pronounced "moss").  For the record, MOS is a statistical scheme that weather forecasters use to help them better predict surface temperatures, surface winds, and several other forecast parameters. After you're finished reading and studying the background material on MOS, you'll be ready to answer the questions below.  We recommend that you keep the Web pages for interpreting NAM MOS (Description of the NAM MOS) and GFS MOS (Description of the GFS MOS) open while you work through this problem.

You are given the NAM MOS and GFS MOS for St. Louis, MO (KSTL), from the 12Z runs on December 6, 2009.

(a)  What were the high temperature forecasts from the GFS MOS and NAM MOS for December 7 and December 8?  Provide a brief comparison.

(b)  What were the low temperature forecasts from the GFS MOS and NAM MOS for December 7 and December 8?  Provide a brief comparison.

(c)  What were the NAM MOS and GFS MOS predicted temperatures for 21Z on December 8? 

(d)  What were the NAM MOS and GFS MOS predicted wind direction and wind speed for 00Z on December 9?  Express wind direction in both degrees and cardinal direction. Proper units on wind speed are a must!  Provide a brief comparison.

(e)  Give the time and date when the NAM MOS and GFS MOS predicted the lowest cloud ceilings.  At what altitude were the ceilings predicted to be?  Proper units are a must.

(f)  Referring to part (e), did the NAM MOS and/or the GFS MOS predict any obstructions to visibility?  If so, provide the specific obstruction to visibility.  Please explain, incorporating your answer in part (d) where it's appropriate.