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Area forecast discussion 
National Weather Service Aberdeen South Dakota 
342 PM CDT Thursday Mar 18 2010 


Short term...tonight through Saturday night 
weak disturbance sliding through the region this afternoon is 
bringing a few very light rain showers/sprinkles. Best precipitation 
chances for the overnight hours still appear to be across the 
southwest County Warning Area. Thermal profiles still supporting a change to snow 
late tonight but not expecting any significant accums. Strong cold air advection 
develops overnight as northerly winds increase. Friday will be much 
cooler with continued breezy north winds. Skies will also be 
mostly cloudy with a few scattered light snow showers/flurries. Current 
satellite pic shows a wealth of clouds moving south across North 
Dakota within the cold air advection and these clouds will be over the region 
later tonight. Winds will slacken late Friday night as surface ridge 
slides across the area...so temperatures will likely sneak into the upper 
teens for many locations. 




Long term...Sunday through Thursday 
some significant model differences came up today. With the GFS 
being the big changer expect to lean more on the European model (ecmwf). The period 
opens with an upper level 500 mb ridge over The Rockies with a Pacific 
low moving onshore in southern Canada. By Monday afternoon the low 
has flattened the ridge and set up a zonal flow across The Rockies 
which will induce a Lee side trough that will move into the 
Midwest. The GFS is much faster and deeper with the approaching 
upper level low that is the remnants of the Pacific low. The European model (ecmwf) 
is advertising a split flow by Wednesday with a closed low over 
the Midwest under a fast westerly flow to the north. The main shot 
of precipitation with this will likely stay south of this area as 
the induced surface low is over Iowa by Wednesday afternoon. With 
time the upper level 500 mb low moves south and intensifies and 
further helps to pull lingering precipitation farther from here. 
Temperatures in the going grids looked good so no major changes 
were made there. 




&& 


Aviation... 
VFR conditions will prevail across the area this evening with ceilings 
generally between 3500 and 7000 feet. A brief -shra is possible 
which may produce a brief lowering into MVFR. 




&& 


Abr watches/warnings/advisories... 
South Dakota...none. 
Minnesota...none. 
&& 


$$ 
Short term...tmt 
long term...Keefe 
aviation...Keefe 


Weather.Gov/Aberdeen