A World of Weather
Fundamentals of Meteorology

Laboratory Exercise #5

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MOS (pronounced "moss"), short for Model Ouput Statistics, is a statistical scheme that weather forecasters use to help them better predict surface temperatures, surface winds, and several other forecast parameters.  MOS forecasts are typically presented in the form of a very compact table - here are instructions for interpreting NAM MOS (Description of the NAM MOS) and GFS MOS (Description of the GFS MOS) - you probably want to keep those descriptions open while doing this problem.

You are given the NAM MOS and GFS MOS for St. Louis, MO (KSTL), from the 12 UTC 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 21 UTC on December 8? 

d.   What were the NAM MOS and GFS MOS predicted wind direction and wind speed for 00 UTC 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.