731 
fxus63 kfsd 082027 
afdfsd 


Area forecast discussion for southeast South Dakota/southwest Minnesota/northwest Iowa 
National Weather Service Sioux Falls South Dakota 
300 PM CDT Friday Aug 8 2008 


Discussion... 
instblty and moisture still seem enough for spotty showers/thunderstorms to develop 
through this evening off the edge of more concentratd activity moving over eastern 
ND and west-central Minnesota this afternoon. For our forecast area this could affect southwestern 
Minnesota into the Spirit Lake/spw area of northwestern Iowa with the threat for 
continued spotty development this area possibly down to slb latr tonight. Main 
shortwave associated with concentratd activity leaves sme weak support behind it 
on NAM and GFS. Threat of precipitation seems none further west and S as activity 
trying to move over NE should stay S/SW of forecast area. Nothng much to 
say on temperatures...lingrng low level srly flow should keep temperatures from 
dropping below guidance values despite mostly clear skies much of the night...60 
to 65 range should cover forecast area. 




Not much to focus on this weekend. For Sat morning...southern wave passing 
through Nebraska might clip far southern County Warning Area with a few trw-...but confidence is 
low and will only go with a 20% pop there. Further NE across portions of 
SW Minnesota...a few thunderstorm- may still be lingering just NE of weak surface fnt 
which will sag into far northern County Warning Area tonight. Short wave should be exiting SW early 
Sat morning and will need to keep at least a small chance there through 15z. 
Fnt will likely remain across far northestern County Warning Area through Sat and could be the focus 
for more spotty thunderstorm- Sat afternoon. This fnt should sag slowly southwestward Sat 
night as surface high builds southward across Minnesota. Drier middle level air will also 
spread into SW Minnesota. So any threat of precipitation Sat night should end from NE 
to SW...but could linger western or southwestern County Warning Area through the night as fnt will 
likely hang up there. Again not much to trigger thunderstorm so will keep probability of precipitation 
very low through Sat night. 


On sun...drier middle level air will push a little further west with fnt still 
lingering over west. Surface heating and temperatures aloft not capped...could southeast spotty 
thunderstorm develop along moist axis whiel eastern County Warning Area expected to be dry. 
Therefore small probability of precipitation warranted for western County Warning Area sun into Sun night. 


Stronger short wave and cold front expected to move across County Warning Area Monday into Monday night 
and this will bring a better chance of thunderstorm to the County Warning Area. Fnt should exit County Warning Area 
Tuesday morning and most of County Warning Area should be dry Tuesday. Another short wave later Wednesday 
into Thursday will bring another fnt across County Warning Area and again another chance of 
thunderstorm. 


Temperatures through sun will be close to norm with some slight cooling sun across 
northestern County Warning Area. As surface high build into western Great Lakes region. Not 
expecting any major swings in temperatures through next week with relatively 
weak will flow aloft through middle week. GFS seems to be the odd model out 
for Thursday and Friday as it tries to dig upper low over Dakotas resulting 
on cooler temperatures and unstable air aloft for convection. Feel more 
zonal flow aloft will occur with upper low further north. This would keep 
bulk of instabil and cooler air to the north. 


&& 


Aviation... 
gnly VFR through 10/00z. Only aviatn concern is very spotty thunderstorm treat 
over northestern part of forecast area. Low level srly flow should keep even any 
MVFR fog threat as well as any St development away...esply with surface ridge 
and unexcitng dewpoints from east to S of area. 


&& 


Fsd watches/warnings/advisories... 


South Dakota...none. 
Minnesota...none. 
Iowa...none. 
NE...none. 


&& 


$$ 
Williams/