Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 120514
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1014 PM MST Wed Jan 11 2017

.SHORT TERM...(This Evening Through Thursday Night)
Issued at 230 PM MST Wed Jan 11 2017

Current surface analysis shows arctic front south of the forecast
area, with high pressure centered over northern MT. Upper level
analysis shows low southwest of Hudson Bay, with another low over
the Pacific NW. Near zonal flow over the northern and central
plains is bringing weak shortwave energy across the region. Lots
of clouds and areas of snow, mostly from the Black Hills to south
central SD at this time. Temps are in the single digits and lower
teens.

Near term models in pretty good agreement on some snow continuing into
the evening hours, especially for areas southeast of the Black Hills,
with accumulations of an inch or two expected across parts of south
central SD. Snow will end by midnight, with some clearing across the
area late tonight. Another surge of arctic air will slide southeast
into portions of the Northern Plains late tonight and early Thursday,
skirting northern and eastern portions of the cwa. Winds will increase
late tonight/early Thursday over northwest SD. Lows will mostly be in
the single digits below zero, with wind chills of 10 below to 20 below
zero later tonight and Thursday morning. However, some areas over
northwest SD will see wind chill values as low as 30 below zero, so
have issued a wind chill advisory there.

Some milder air will begin to move into at least northeast WY and the
Black Hills on Thursday. Highs will range from the single digits over
northwest SD to the upper teens and lower 20s over much of northeast WY
and the Black Hills. A weak disturbance will then cross southern SD
Thursday night, with a chance for light snow. Any accumulations at this
time look to be less than an inch. Lows will mostly be 5 below to 5
above zero.

.LONG TERM...(Friday Through Wednesday)
Issued at 230 PM MST Wed Jan 11 2017

By Friday, weak upper ridging will develop over the northwestern
CONUS, and the Canadian low pressure systems will shift eastward,
along with the arctic airmass. This will initiate a gradual
warming trend through early next week, with temperatures returning
to near average values (mid 30s) Sunday into Monday. Dry weather
is also expected through the weekend. An upper low will track
under the ridge and lift northeastward across the central plains
on Monday. Latest GFS/EC/GEM all show precip staying just
southeast of south central SD.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Thursday Night)
Issued At 1011 PM MST Wed Jan 11 2017

Areas of MVFR CIGS over parts of northeastern Wyoming and
southwestern into south central South Dakota will improve to VFR
during the areas of the night. VFR conditions will then continue
through Thursday and Thursday evening.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Chill Advisory until 11 AM MST Thursday for SDZ001-002-
     012>014-073.

WY...None.
&&

$$

SHORT TERM...26
LONG TERM...15
AVIATION...10



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