487 
fxus63 kfsd 120913 
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Area forecast discussion for southeast South Dakota/southwest Minnesota/northwest Iowa 
National Weather Service Sioux Falls South Dakota 
315 am CST Friday Mar 12 2010 


Discussion... 
will continue advisory across southwestern County Warning Area through expiration of 12z as web cams and 
surface observation continue to show reduced visibilities along with areas of snow. Also will 
continue dense fog advisory across SW Minnesota through 15z where fog is widespread...and 
locally dense. For now will leave northwest Iowa out of advisory although areas of 
dense fog can also be expected. 


Upper low over SW Iowa will continue to drop southeastward through Sat with weak lift 
persisting across County Warning Area espec today into this evening. So will need to keep 
probability of precipitation fairly high across County Warning Area today into early evening. With temperatures above 
freezing not much threat for accumulate snow...but will keep the mix 
mention for at least this morning...and then rain this afternoon as 
warmer air alofts wraps southwestward across County Warning Area. Precipitation chance should decrease 
overnight and may end up just being areas of drizzle and fog most of 
night into Sat morning. Not much range in dirunal temperatures today 
and today with a 2 to 5 degree vaiance through the period. 


Doesn't look too impressive for much precipitation on Sat or sun but could 
still see a stray light shower or 2 clip eastern County Warning Area with cyclonic flow 
aloft. This flow will keep County Warning Area cloudy or mostly cloudy through sun. This will have 
an effect on temperatures and slightly cooler than guidance seems the way to go 
and indicated by ensemble MOS guidance. Next short wave will drop southeastward across County Warning Area 
on Monday and may produce a few rain shower- and will keep lop probability of precipitation across eastern County Warning Area 
for now. This short wave should help push along the this stubborn upper low. 
Most of next week looks warmer with zonal flow aloft...with another 
storm possible by next weekend. 


&& 


Aviation... 


Periodic rain/snow will continue across the region today...with 
general IFR conditions expected across the area through 15z. Will 
see visibilities generally improve into the MVFR range after this 
time...though ceilings will remain in the IFR range. Sustained 
northwesterly winds of 15 to 20 kts...with higher gusts...will 
persist from the Interstate 29 corridor westward through 00z this 
evening...before diminishing tonight. 


&& 


Fsd watches/warnings/advisories... 
Iowa...none. 


Minnesota...dense fog advisory until 9 am CST Friday for 
mnz072-080-081-089-090. 


NE...none. 


South Dakota...Winter Weather Advisory until 6 am CST Friday for 
sdz050-057-063. 


&& 


$$