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fxus63 kabr 062028 
afdabr 


Area forecast discussion 
National Weather Service Aberdeen South Dakota 
328 PM CDT Sat Sep 6 2008 


Short term...tonight through Monday night 
isolated/widely scattered showers and thunderstorms continue across the area 
this afternoon...with a stronger small line of storms moving south 
across northern Spink County. With low freezing levels...hail 
continues to be main concern with dime sized hail reported in 
Warner earlier this afternoon. More development of showers noted 
upstream across northwestern South Dakota and southwestern North 
Dakota closer to main upper wave. This wave will move through the 
region tonight and still looking at a good chance for showers 
across much of the area. Left likely probability of precipitation in grids for overnight 
hours as this upper wave moves through. Could see a few lingering 
showers Sunday morning across the east and have left low probability of precipitation in 
the grids during this time. Next system moves in Sunday night and 
Monday and models have trended much farther north with this system 
and associated area of precipitation. A good bet that much of southern 
South Dakota receives rainfall with this system and have 
added/increased probability of precipitation quite a bit for Sunday night and Monday. 
Plenty of upglide taking place across the southern County Warning Area Sunday 
night. Precipitation moves out of the region Monday night as high 
pressure builds in. 


Temperatures will remain cool throughout the period with highs 
generally in the 60s and lows in the 40s. 




Long term...Tuesday through Saturday. 
Focus of the extended period is on the Wednesday frontal boundary 
moving across the area. Models are doing pretty good with this at 
least on the broad scale. The period opens with this area under 
northwest 500 mb flow aloft. There is also a closed low off the West 
Coast of California. An upper level 500 mb trough is rotating south 
through western Canada as it strengthens and absorbs the remnants 
of the West Coast low. By Wednesday this trough flattens the upper 
level flow and this area is left under zonal flow. This also 
induces a Lee side surface trough along the Front Range of The 
Rockies. As the upper level 500 mb trough continues to move east the 
cold air behind it from central Canada helps form a cold front 
that will move through the region late Wednesday. With mostly 
Pacific air upstream Wednesday the cold front will be moderated 
and have a fleeting affect on temperatures. However it will likely 
set off a round of thunderstorms Wednesday afternoon into 
Thursday. Have stayed very close to going grids as there was 
nothing in the new model data to contradict the going package. 
After the front passes the 500 mb upper level ridge will rebuild and 
surface high pressure will build into the area. This will allow 
temperatures to rebound late in the period. Mex guidance suggests 
temperatures of two or three degrees above climatology in the 
final period where climatology strongly moderates extremes. 




&& 


Aviation... 
several upper level features will affect the weather across the 
region today. The first wave is causing showers in parts of eastern 
South Dakota. Most of these showers are south of this area on the 
latest WSR-88D returns. Katy may see some showers this afternoon. 
Thunderstorms will be more likely this evening as a stronger wave 
and a surface front move across the region. Ceilings are good VFR 
at this time and visibility is unrestricted. This evening it will 
be possible to have some brief periods of MVFR ceilings and 
visibility with the heavier showers. 




&& 


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


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


Weather.Gov/Aberdeen