Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 070449
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1049 PM CST Wed Dec 6 2017

.SHORT TERM...(This evening through Thursday)
Issued at 313 PM CST Wed Dec 6 2017

In the wake of the cold front that brought light snow to the
region this morning, a tight pressure gradient will continue to
force gusty northwest winds in the 25 to 35 mph range through
sunset. Most locations will have a chance for flurries through the
evening as the scattered to broken cloud layer sits in dendritic
growth layer. Clouds will clear throughout the night, leading to
a good scenario for strong radiational cooling. However, lingering
northwest winds may prevent the surface inversion reaching its
full potential. Nevertheless, 925 hPa temperatures of -12 to -14 C
mean that even without an inversion, tonight looks colder than
nights past, and one of the coldest so far this season, with lows
in the single digits. Wind chills will be in the negative single
digits midnight through mid-morning Thursday, so those spending
time outside will want to bundle up. High temperatures Thursday
will be below average with cold air firmly in place.

.LONG TERM...(Thursday night through Wednesday)
Issued at 313 PM CST Wed Dec 6 2017

Overall, the next 7 days looks quiet weather-wise, with a few
periods of light snow and slightly below average temperatures. The
large-scale weather pattern does not change much over this
timeframe, meaning no big changes in weather conditions. The
amplified upper-level flow pattern remains, with a ridge centered
over the the West Coast and a trough stretching from Hudson Bay down
through the eastern states. This puts our region under the
meridionally-oriented jet stream, with a number of weak weather
systems moving through over the next week. A few time periods are
worth noting:

Late in the day Thursday into Thursday night, mid-level warm air
advection will provide enough moisture for light snow Friday
morning. Amounts look well under an inch at this point, and flurries
with only trace accumulations may be more common.

On Sunday, the trough briefly retreats eastward, leading to warming
for the surface and mid-levels of the atmosphere. The forecast calls
for southwest and west winds with above average temperatures in the
high 30s to around 50 for south central SD Sunday afternoon. This
looks to be the warmest day out of the next 7.

A shortwave trough drops south out of Canada on Monday, bringing a
reinforcing shot of cold air and another chance for light snow. This
weak front could stall over the area, leading to lingering light
snow on Tuesday. However, models do not agree on the exact position
of these features, so confidence is low in exactly where this light
snow will fall.

Mid-next week into next weekend, this pattern of light snow
events every few days looks to repeat, with no major pattern
change.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1047 PM CST Wed Dec 6 2017

VFR conditions are expected through the TAF period with breezy
west-northwest winds of 10 to 15 knots, gusts to 20 knots.

&&

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

$$

SHORT TERM...VandenBoogart
LONG TERM...VandenBoogart
AVIATION...05



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