291 
FXUS63 KFSD 202052
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
252 PM CST Wed Dec 20 2017

.SHORT TERM...(This evening through Thursday)
Issued at 251 PM CST Wed Dec 20 2017

Models have bounced back a touch, but still indicating less than 2 
inches for pretty much all locations. Forcing pretty much the same 
as the past couple of days and due to the unfavorable temperature 
profile and a general lack of moisture not expecting any measurable 
precipitation before about 9z tonight. Soundings still indicate a 
brief window over northwest IA late tonight and early Thursday 
morning where a little light freezing drizzle will be possible but 
at this time not expecting any major problems. A very small chance 
that some patchy very light freezing drizzle could occur as far 
north as Interstate 90 but not a good enough chance to mention.

Closer to 12z around Chamberlain and Huron temperatures will begin 
to become cold enough to support precipitation and at this time it 
looks to be all snow. With the main component of the low and mid 
level frontal forcing cold air advection expect the band to be on 
the lighter side. There is a hint of a little instability above the 
mid level front so there could be a quick uptick in snow development 
from about 13z through 17z, but still do not think that this will 
cause any localized heavier snow. Not out of the question for 
someone to get closer to 3 inches, but pretty unlikely. This forcing 
slides south through the day and should slip into northwest IA by 
late afternoon. Did bump up snow amounts a touch, aiming for 
something close to an inch in southeast SD and southwest MN. Amounts 
should be less over northwest IA as forcing is weakening. There is a 
trailing mid level band of cold air advection collocated with some 
decent dendritic temperatures, so will linger the chance for light 
snow a little longer in case this band produces something, but will 
be pretty light.

Temperatures will drop some this evening but remain steady through 
much of the night with stronger winds and clouds in place. MVFR 
stratus will continue to advect northward through the night from 
central Nebraska. Temperatures will be at about the warmest around 
sunrise, then steady or falling through the day. The exception could 
be central SD where some sunshine will be possible in the afternoon. 
 
.LONG TERM...(Thursday night through Wednesday)
Issued at 251 PM CST Wed Dec 20 2017
 
Upper level energy remains somewhat zonal Friday through Saturday 
night before turning more northerly. This will keep less cold air in 
place for the weekend. Highs should be in the upper teens to mid 20s 
with lows about 5 to 15 above. 

Will not really mess much with what is given Monday through 
Wednesday. Models have been all over the place on how to handle the 
low level cold air. Some colder air lingering out there so there is 
good potential for a couple of pretty cold days, just not easy to 
say which days. The latest ECMWF would hint that Tuesday could be 
the coldest but not that cold Monday or Wednesday. Also suspect
that we will have a few periods of light snow next week with some
fairly favorable dendritic temperatures in the vicinity so that
any wave producing some convergence will have a good chance to
produce snowfall.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1140 AM CST Wed Dec 20 2017

MVFR ceilings streaming north through central Nebraska to just
south of KYKN at 1740z. Expect this northward transport to slow a
bit through the warmer part of the day, but then lift north and
east after sunset. Widespread MVFR ceilings after about 5z
Thursday, maybe some IFR conditions in northwest IA. Patchy light
freezing drizzle will be possible in northwest IA early Thursday
morning but confidence not real high. A band of snowfall will
develop in central SD and spread south and east through the day.
Lighter accumulations less than 2 inches are anticipated.


&&

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

$$

SHORT TERM...08
LONG TERM...08
AVIATION...08