096 
FXUS63 KFSD 041946
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
246 PM CDT Wed Oct 4 2017

.SHORT TERM...(This evening through Thursday)
Issued at 242 PM CDT Wed Oct 4 2017

Mid level clouds are rapidly thickening from the south this 
afternoon as an otherwise very nice Fall day continues. The main 
forecast concerns continue to focus on rain chances over the 
upcoming 72 hours. 

Tonight: Shortwave ridging at 850 mb slides to the northeast this 
evening, allowing broad southwesterly warm advection and 
isentropic lift to develop across the Tri-State area. Model 
guidance has trended drier today with overnight rain chances 
focusing over north central and northeastern SD after midnight 
tonight. Very scattered showers and perhaps a few rumbles of 
thunder will be possible through daybreak even further south, as 
more widespread convection tries to build along and north of the 
warm front in North Central and eastern Nebraska by daybreak. 

Thursday: High resolution models suggesting an inverted sfc trough 
begins to pivot across the CWA through the day. Convection south
of the CWA early in the day should take some of the focus for 
precipitation away from the area, but the gradual advection of 
lower stratus should intensify prior to daybreak. Soundings 
showing an increased potential for drizzle or sprinkles along and
east of the sfc front into the afternoon as the lift appears more
shallow in nature. Have generally reduced QPF over much of the 
CWA through the day. 


.LONG TERM...(Thursday night through Wednesday)
Issued at 242 PM CDT Wed Oct 4 2017

Thursday Night:  Winds at the sfc turn more northernly and shortwave 
ridging slides in during the late afternoon hours, which should help 
push the risk for precipitation southward briefly. A stronger 
shortwave and more favorable upr jet structure moves in Thursday 
night into Friday with an increasing rain chance after midnight and 
into Friday. 

Friday-Friday Night: Upper troughing swings through the Plains 
Friday night, and keeps the chance of rain high from Friday 
afternoon through midnight Friday, focused along a Lake Andes to 
Sioux Falls and Marshall line eastward. The risk of thunder is 
generally low, but confined to the southeastern third of the CWA. 
The heavy rain threat looks to stay across Central and Southern 
Iowa. 

This weekend: Broad westerly flow will bring warmer temperatures on 
Saturday, albeit very breezy.  Have bumped up winds a few knots on 
Saturday afternoon. Continued dry conditions into Sunday. 

Next week:  A large upper trough swings through the central US to 
start the week, ushering in below normal temperatures quickly on 
MOnday and Tuesday. GFS/ECMWF in a high degree of disagreement 
for Monday and Tuesday regarding an upper trough moving through 
the CONUS. With more ensemble agreement towards the GFS/GEM 
solutions, have maintained PoPs Monday night into Tuesday. Still a
large area of wiggle room for this portion of the forecast to 
change. Have lowered temperatures slightly through early next 
week, with decent chances of a widespread frost in the region 
Wednesday morning.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1216 PM CDT Wed Oct 4 2017

VFR conditions expected into the overnight hours. Lower ceilings
begin to advect north later tonight, with a chance for showers and
isolated thunderstorms after midnight. IFR ceilings will be
possible Thursday morning, with greater probabilities of drizzle
or light showers through the morning. If more widespread drizzle
could form, then visibilities, especially along and east of I-29
could fall into MVFR levels. 


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...Dux
LONG TERM...Dux
AVIATION...Dux