267 
FXUS63 KFSD 221133
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
533 AM CST Sun Jan 22 2017

.SHORT TERM...(Today and Tonight)
Issued at 319 AM CST Sun Jan 22 2017

Persistent stratus will continue to blanket much of the forecast 
area today, in the wake of slowly departing upper low. One last lobe 
of vorticity swinging through lingering cyclonic flow aloft could 
produce enough weak lift for patchy light precip across eastern 
portions of our area. CAMs have picked up on this with some splotchy 
very light QPF, and seeing some very light echoes develop on 
regional radar north of Sioux Falls, so will carry some low pops 
from east of Brookings to Orange City line through this morning. 
Lack of mid level/ice-bearing moisture layer evident on satellite 
and in forecast soundings, so drizzle/freezing drizzle should be the 
dominant precip type. With stratus expected to remain extensive, 
expect another day with highs generally in the mid-upper 30s. 

Could see some clearing work as far east as the James Valley or 
possibly lower portions of the I-29 corridor by sunset. Model RH 
progs indicate stratus could remain pretty stubborn across southwest 
MN/northwest IA through tonight, though fog does not appear as 
likely, as continued westerly low level flow should allow some drier 
near-surface air to work eastward. The lack of stratus and light 
winds in our west should allow temperatures to fall into the lower 
20s tonight, while eastern areas hold in the mid-upper 20s under the 
lingering stratus.

.LONG TERM...(Monday through Saturday)
Issued at 319 AM CST Sun Jan 22 2017

Focus in the long term will be on snow chances Mon night through Wed.

As a longwave trough approaches the plains on Monday GFS/ECM are in 
fair agreement on strength and timing of the H5 low and associated 
surface features.  Moisture is readily available throughout the 
duration as evidenced by soundings and time/height sections. Daytime 
warming on Tues will allow for some RA/SN mix with a period of all 
rain to the south around SUX before changing over to snow by Tuesday 
evening.

Because of the duration of this event, going from late Monday night 
with snow finally tapering off by Wed morning, 3-6" storm total is 
still a good possibility.  Best chances/timing of snow looks to be 
from late Tues night into Wed morning as the ECM is showing some 
negative tilt and deepening of the H5 low (GFS not so much on the 
tilt but does show some deepening) as well as a stronger shortwave 
passing through around 00z.  It's still a bit early to get too 
specific on where exactly the higher snow amounts will fall so I 
didn't make huge changes from the previous forecast.

After this system moves off to the east by Wed, temps will go back 
to at or below freezing for highs and teens for lows.  Also in it's 
wake will be increased wind as surface gradient remains tight until 
at least Wed night.  This will allow for blowing snow and have kept 
a mention of this in the forecast.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 533 AM CST Sun Jan 22 2017

Stratus/areas of fog will continue to be the primary aviation
concerns through this TAF period. Will start with areas of MVFR to
IFR visibility in fog, mainly near/north of I-90, with localized
LIFR east of the Buffalo Ridge. Visibility is expected to be less
of an issue as the day progresses, as westerly flow works to dry
out the near-surface air. Stratus will be much more stubborn,
however, with MVFR-IFR ceilings expected to persist for much of
the area. Western edge of stratus may shift east of the James 
Valley at times, but is likely to spread back into the area late 
in the TAF period.

&&

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

$$

SHORT TERM...JH
LONG TERM...Sally
AVIATION...JH