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Area forecast discussion 
National Weather Service Aberdeen South Dakota 
350 am CST Sat Nov 21 2009 


Short term...today through Monday 
today will be breezy/windy across much of the County Warning Area as pressure 
gradient tightens ahead of an approaching cold front. 925/850 
winds on the order of 40-50 knots but do not expect wind gusts to 
be this high. The cold front tracks east across the County Warning Area 
tonight...bringing cooler temperatures for Sunday. After much 
above normal temperatures in the 50s today...highs will drop back down 
into the 40s for Sunday. Weak shortwave moves through the area on 
Sunday but best moisture availability remains east of the region 
in Minnesota so will keep forecast dry. Attention then turns to the 
approaching storm system which begins to affect the region late 
Sunday night and Monday. GFS remains the furthest north of all 
models and is quicker...but has shown a noticeable trend to the 
south...trying to come in line more with the more consistent ec 
and Canadian solutions...which have always been further south. The 
new 00z ec is even a tad further south than its previous run but 
whats interesting is that it has developed a more pronounced 
inverted trough which noses northward along the South Dakota/Minnesota border. This 
could spell out decent precipitation chances this far north...even though 
main surface low is well south of the area. Will have to keep an eye 
on this development. Thermal profiles still suggest mostly rain to 
start off...then changing over to snow from west to east towards 
the end of the event. Have not made real significant changes to 
weather/probability of precipitation during the short term period. 




Long term...Monday night through Friday 
a somewhat active pattern still appears on tap for the first part 
of the long term. All models still produce a decent looking yet 
progressive upper low over the central/northern plains through middle 
week. The European model (ecmwf) remains the slowest and furthest south of all 
deterministic 00z runs. Meanwhile the Gem has trended toward the 
GFS. With some uncertainty in the forecast...felt that the best 
policy was to stay somewhat close to the inherited solution. Rain 
and snow will be possible into Tuesday before becoming mostly snow 
by Tuesday night. It appears the highest precipitation probabilities will 
exist over the big Sioux Valley/Sisseton hills where an inverted 
trough may hang out for 24 hours or more. Temperatures were only 
modified slightly after looking at the latest long range temperature forecasts. 




&& 


Aviation... 
through today VFR conditions will prevail although blustery winds 
will arrive shortly after daybreak. 




&& 


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


$$ 
Short term...tmt 
long term...tdk 
aviation...tdk 


Weather.Gov/Aberdeen