Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 121748
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1048 AM MST Fri Jan 12 2018

.DISCUSSION...(Today Through Thursday)
Issued at 250 AM MST Fri Jan 12 2018

Latest analysis shows a shortwave crossing the area, with weak
isentropic lift producing some light snow and flurries as colder
air moves in at the surface. Snow accumulations will be minimal
as this system moves through this morning. Most areas will see
less than 1/2 inch of new snow accumulation although locally
higher amounts are expected, especially over the northern Black
Hills, where 1 to 3 inches are possible.

The Wind Chill Advisory that was previously issued for
northwestern South Dakota will remain in effect until 11 AM MDT
this morning as the combination cold temperatures and wind will
keep wind chill readings as cold as 25 below zero this morning.

Much colder air will continue to flow into the region today and
tonight with the center of 1044+mb high dropping into the central
and eastern Dakotas tonight. The surface high will quick be
displaced to the east on Saturday, as a warm front pushes into
northeastern Wyoming and western South Dakota. Some uncertainty
remains as to how quickly the temperatures will warm on the
plains of western South Dakota, but the Black hills and
northeastern Wyoming will see highs in the 30s. A relatively mild
day is expected across the area Sunday as warmer air continues to
move in from the southwest. An upper trough rotating around the
west side of a Hudson Bay low will drop into the Dakotas late
Sunday/Sunday night. This will bring another round of light snow
as yet another arctic front backs into the forecast area.

Models remain in general agreement for middle of next week, with
an upper level ridge shifting across the northern plains. Above
average temperatures expected for much of the area from
Wednesday into the end of the week.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1048 AM MST Fri Jan 12 2018

Areas of MVFR conditions will continue through the afternoon and
into tonight, with some IFR conditions redeveloping tonight,
especially across the Black Hills area. Areas of light snow and
flurries over western and south central SD will dissipate early
this afternoon. There is a chance for light snow tonight into
Saturday morning from far northeast WY to the northern Black Hills
area.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION...10
AVIATION...26



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