209 
fxus63 kfsd 062023 
afdfsd 


Area forecast discussion for southeast South Dakota/southwest Minnesota/northwest Iowa 
National Weather Service Sioux Falls South Dakota 
323 PM CDT Monday Oct 6 2008 


Discussion... 
for tonight...the band of rain over the western County Warning Area should slowly 
decrease in coverage as the showers and thunderstorms over Nebraska 
move north and take over. Continues to look like a very good chance 
for an additional inch to inch and a half of rainfall generally 
south and east of a Brookings to Yankton line in a very moist 
atmosphere. Low level shear along and just ahead of the incoming 
front fairly impressive and some concern that a few funnels will be 
possible the evening...but hail and strong winds seem unlikely with 
very Low Cape values. Otherwise...much drier air will filter in from 
the west with a fairly distinct back edge to the precipitation 
expected to develop. Lows should range from the middle 40s west to the 
middle 40s around Storm Lake. 


Outside of some early morning rain over parts of northwest Iowa on 
Tuesday morning...the Tuesday through Thursday time frame looks to 
be relatively quiet. A fairly weak cold front will push through on 
Tuesday morning with winds stirring up into the 15 to 25 miles per hour range 
for most locations. Do expect these winds to slowly taper off during 
the middle to late afternoon as the pressure gradient relaxes. Being 
fairly mixy...expect highs to be mild and climb into the middle and 
upper 60s. Maybe even some lower 70s in central South Dakota. 


Tuesday night still looking mostly clear and calm so will continue 
lows in the upper 30s to lower 40s. 


Wednesday should be another moderately mixy day...although winds 
should mainly be in the 10 to 20 miles per hour range. Expect mild highs again 
with little in the way of any significant clouds...ranging from the 
upper 60s to middle 70s. 


Wednesday night will see a reinforcement of the drier air from the 
north and expect lows in the middle 30s to lower 40s. May see a slight 
increase in high clouds over the northern County Warning Area...but not much to be 
concerned about. 


Thursday should see the winds slowly becoming more northeasterly as 
low pressure begins to develop over the western High Plains. 
This...along with increasing clouds will keep highs down a few 
degrees and mainly in the 60s. Chances for any rainfall should 
remain north and west of the area. 


By Thursday night the right rear quadrant of a strong northern stream 
jet will likely aid in focusing some middle level banded precipitation. 
Better middle level frontal forcing expected to be north and west of 
the County Warning Area but still close enough to warrant a small pop over central 
South Dakota. 


In the latter periods(fri-mon)...fairly large differences still 
exist from model to model and run to run so confidence is somewhat 
low...but a little higher than the past couple of days. 
Overall...still looks like a strong upper level wave will develop 
over The Rockies on Friday and lift onto the plains Friday into 
Sunday. The GFS and Canadian models continue to be faster than the 
European model (ecmwf) as has been the case the last couple of days. But...a look at 
the Canadian and GFS spaghetti plots show that the 0z runs of each 
model are on the quick side compared with the rest of the members 
and that many members now support the slower European model (ecmwf) output. So...will 
side a little closer to the European model (ecmwf) output for this event. What does 
this mean...mainly warmer temperatures for the weekend with somewhat 
less of a chance for precipitation early in the period. Will be 
reducing probability of precipitation for Friday but continuing with Middle Range probability of precipitation Saturday 
and Sunday. Regardless...still looks like off an on chances for rain 
on the weekend. By Monday...expect most of the energy to be east of 
the area but this is still pretty much up in the air. Will not stray 
too far from climatology but lean on the cool side. 


&& 


Aviation... 
mostly MVFR with local IFR conditions into the James Valley where 
numerous showers are occurring. Showers will slowly shift ewrd 
today...eventually moving into SW Minnesota and northwest late in the afternoon. 
Clearing from west to east late tonight and tomorrow as surface trough 
pushes into eastern Minnesota and eastern Iowa. 


&& 


Fsd watches/warnings/advisories... 
South Dakota...none. 
Minnesota...none. 
Iowa...none. 
NE...none. 


&& 


$$ 
Ryrholm/Williams