Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 071055
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
355 AM MST Wed Dec 7 2016

.SHORT TERM...(Today Through Thursday Night)
Issued at 255 AM MST Wed Dec 7 2016

Upper level analysis has large trof over most of the CONUS with
closed low over northern MN. Fast cyclonic flow in place across
the southern half of the CONUS, with another disturbance over the
Central Rockies moving east toward the Central Plains. Skies are
partly to mostly cloudy across the Dakotas, with high clouds
streaming across southern SD, and lower stratus decks across
northern SD and northeast WY. At the surface...gusty west to
northwest winds continue to the northeast of the Black Hills.
Temps at 3am range from near zero to around 5 degrees.

Today...Frigid air will continue to push into the area as Arctic
high pressure settles into the Northern Plains. Skies will be
variably cloudy today, with Colorado shortwave moving east through
Nebraska. Main band of snow with this system will remain south of
the forecast area. Today will be the coldest day of the week with
high temperatures mainly in the single digits to around 10 degrees
in a few places. With the breezy winds, wind chill values will
remain 15 to 30 degrees below zero through the morning hours. Some
moderation in wind will occur by late afternoon across western
portions of the area.

Lows late tonight will plummet well below zero in most locations
as Arctic high pressure center slides into western portions of the
area. Some locations will see temps fall below 10 degrees below
zero. West to northwest winds of 10 to 20 mph will push wind
chill readings back down to 20 to 30 degrees below zero across
much of the area. A wind chill advisory will likely have to be
issued again for Northeast Wyoming and Western SD.

Arctic high pressure moves across the Dakotas on Thursday. After
a very chilly start, temperatures will moderate a bit, but remain
in the single digits to teens for most locations. Winds will be
light. By Thursday night, light return flow begins across western
portions of the area. Low temperatures will range from zero to ten
below zero.

.LONG TERM...(Friday Through Tuesday)
Issued at 255 AM MST Wed Dec 7 2016

Warm front pushes into the cwfa Friday allowing temps to modestly
warm from nern WY through srn SD, with a small chance for light
snow or flurries across cntrl SD. A robust upper trof will then
work through the nrn plains on Saturday and bring a good chance of
light snow to much of the area, although moisture will be limited
and snow totals only an inch or two. Longer range guidance still
suggesting another strong push of arctic air early next week, with
the ECMWF being the most aggressive at this time.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 255 AM MST Wed Dec 7 2016

Gusty northwest winds will continue on the South Dakota plains
through the period. Mainly VFR conditions will dominate
southwestern South Dakota. Areas MVFR CIGS are expected across
northwest South Dakota and northeast Wyoming through this
afternoon with improvement tonight.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Chill Advisory until noon MST today for SDZ001-002-012-013-
     024-025-027>029-041-072-073.

WY...Wind Chill Advisory until noon MST today for WYZ054>058-071.

&&

$$

SHORT TERM...15
LONG TERM...Johnson
AVIATION...Johnson



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