Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 300911

Area Forecast Discussion
National Weather Service Sioux Falls SD
411 AM CDT Thu Mar 30 2017

.SHORT TERM...(Today and Tonight)
Issued at 410 AM CDT Thu Mar 30 2017

Weak returns showing up on the radar this morning showing light
rain/drizzle lingering across the area.  Isentropic lift on the 290K
surface is expected to transition to weak isentropic downglide
through the early morning hours.  Still have some relatively deep
saturation lingering across portions of southwest Minnesota into
northwest Iowa, so left some low pops for drizzle through the
morning hours. With relatively deep saturation and weak cold air
advection in the near surface layer, will be a struggle to warm
across the east.  Further to the west, drier air will advect in
allowing for some warming, but will still be a relatively cool day
with temperatures struggling to get to seasonal norms.

With stratus lingering into the overnight hours, have nudged
forecast lows up slightly.  Could see some fog develop in areas that
picked up rainfall over the past day or so.  At this point,
confidence is low enough that skies would clear that did not include
mention of fog, but if stratus shows signs of trying to build
towards the ground tonight, may need to add the mention.

.LONG TERM...(Friday through Wednesday)
Issued at 410 AM CDT Thu Mar 30 2017

Fairly quiet conditions expected Friday into Saturday, as ridging
surface and mid-upper level influence the region. Could still have a
fair amount of stratus around early Friday, but general subsidence
should bring increasing amounts of sunshine by afternoon, allowing
temperatures to climb into the 50s. Upper trough moves across the
region during the latter half of the weekend, which will spread more
cloud cover over the area, along with a chance of light rain. The
main question remains how far north the precipitation will spread.
GFS/NAM show a stronger trough, pulling deep moisture and resultant
precipitation farther to the north. Canadian/ECMWF are quite a bit
weaker with the trough, and spread little if any rainfall into our
area except across the far south. Will carry a chance up to Highway
14, but keep high chance/likely pops concentrated in the far south
Saturday afternoon/night. Trough and associated rain/clouds should
exit to the east through the day Sunday, with temperatures warming
into the 50s most areas, with some lower 60s possible west.

Another brief respite between systems on Monday/Monday night, before
another system moves across the Plains through the middle part of
next week. Deterministic models yesterday were showing fairly good
agreement with this system affecting the region Tuesday/Wednesday
next week. That is not the case with the latest 30/00Z runs, where
the Canadian now shows a much weaker/open wave swinging through,
while the GFS/ECMWF continue to show a stronger/more wrapped up
system tracking through the central Plains. Ensembles provide little
guidance in one direction or the other, as they too display much
variability in possible solutions in this time frame. All solutions
do show some potential for precipitation, especially late Tuesday
into Wednesday, so did not deviate from the broad model consensus
likely pops spreading into our west late Tuesday, then shifting into
eastern areas by Wednesday morning. The question will be just how
much precipitation will fall, and potentially whether we will see
some snow mix in at any point, as all three deterministic models are
indicating some sub-zero 850mb temperatures wrapping into the back
side of the system by later Wednesday/Wednesday night.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1041 PM CDT Wed Mar 29 2017

Low stratus will continue to blanket the region through the TAF
period. Expect MVFR ceilings throughout the forecast area, however
portions of south central SD, including HON may see some
spotty improvement to low end VFR late tonight into Thursday.
Light rain across far southeast SD and northwest Iowa will
continue to gradually taper off from west to east through Thursday




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