747 
fxus63 kabr 230926 
afdabr 


Area forecast discussion 
National Weather Service Aberdeen South Dakota 
326 am CST Monday Nov 23 2009 


Short term...today through Wednesday 
current water vapor imagery and RUC analysis shows main 500mb 
trough over the northern rockies. Broad surface low exists across 
eastern Colorado and this low will deepen today as upper trough 
shifts east into the plains. RUC also showing a lead 700mb wave 
moving north across the County Warning Area with the best lift across the eastern 
County Warning Area. Scattered light showers have been ongoing over the past couple 
hours east of the James River. 


For today...inverted surface trough will become better defined along 
the South Dakota/Minnesota border with a wave of energy riding along this trough. 
Will maintain 30-50 probability of precipitation across the northeastern County Warning Area for today. 
Main upper/surface low will move east across the Central Plains today 
through Tuesday morning and models have shifted these features 
south a tad. Only expecting precipitation today near the inverted surface 
trough/weak upper wave combo...while any precipitation associated with 
the main surface low will stay south of the region. Late tonight into 
Tuesday morning there is a bit of uncertainty regarding if/when 
surface low takes a jog to the northeast and possibly spread precipitation 
into the far southeastern County Warning Area. Will keep chance probability of precipitation across the 
eastern County Warning Area and have not gone likely at this time. Thermal 
profiles still supporting a mostly rain event. Could be a 
rain/snow mix along the western edge of precipitation shield late tonight 
into Tuesday morning but do not expect much in the way of accums. 


Next shortwave drops southeast over the area late Tuesday night 
through Wednesday. Fairly wound up 500mb low looks to move through 
with fairly steep lapse rates due to the cold air aloft. 
Possibility exists for isolated/scattered light snow showers as this wave 
moves through and will stick with the 20/30 probability of precipitation. Could even be a 
light dusting of snow across the northeastern County Warning Area. Wednesday will 
also be breezy/windy across the entire County Warning Area as this quick moving 
wave moves through. 




Long term...Wednesday night through Sunday 
the 00z models maintain a progressive middle level flow situation 
through the long term...along with occasional split flow 
characteristics. Meanwhile the majority of the forecast period 
should be dry as middle level ridging asserts itself across the 
northern plains through Friday. Afterward an approaching middle level 
trough for the latter part of the weekend could bring some light 
precipitation...but for now chances look pretty minimal based on model 
soundings...thus will maintain dry forecast. Temperatures should 
average near to above normal for most of the time period. And 
based on latest European model (ecmwf)/GFS forecasts...did decide to bump up temperatures a 
touch ahead of advancing front next weekend. Otherwise no major 
changes were made to the forecast. 




&& 


Aviation... 
MVFR/IFR ceilings will continue around kabr/Katy through the 
morning...with improvement expected this afternoon. Meanwhile 
kpir/kmbg are expected to remain VFR through today. Visibilities 
meanwhile should be mainly VFR except perhaps around Katy where 
there is a better chance of light rain...and consequently some 
MVFR visibilities due to fog and rain. 




&& 


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


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


Weather.Gov/Aberdeen