Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 140506
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1006 PM MST Tue Feb 13 2018

.DISCUSSION...(This Evening Through Tuesday)
Issued at 320 PM MST Tue Feb 13 2018

Current surface analysis shows remnants of arctic front stretching
from eastern MT, to far eastern WY, to low pressure over southeast
CO. Upper level analysis shows persistent northwest flow from
southwest Canada through the Northern Plains, with an area of low
pressure cutoff along the CA coast. Skies are mainly clear across
the area with winds mostly from the south to southwest, though
winds in more terrain influenced areas are light and variable.
Temperatures are all over the place this afternoon, ranging from
around 20 over portions of northwest SD to the 40s over the
northern and eastern slopes of the Black Hills where downsloping
winds are occurring.

Milder air will continue to push northeast across the area late
today and tonight. Lows tonight will mostly be in the mid teens to
mid 20s, with sheltered areas of northwest SD being the coolest in
general. The northern and eastern foothills will likely be milder
overnight. Southwesterly winds can be expected in most areas, breezy
at times over northeast WY, especially the higher elevations of
Campbell County.

Gusty winds will continue into Wednesday across northeast WY. Highs
will be in the 40s across much of the area, possibly a bit cooler
across parts of northwest SD. Some 50s are likely over the northern
and eastern slopes of the Black Hills and foothills as downsloping
winds persist. Clouds will begin to increase from the north and west
in the afternoon as next cold front slides south across MT and ND.

The front will eventually move south across the forecast area
Wednesday night and early Thursday. The pcpn with the system will be
post frontal as shortwave moves across late Wednesday night and
Thursday. The best chances for snow will be across northeast WY into
the northern Black Hills and parts of northwest SD, where 1 to 2
inches are possible. Elsewhere, less than an inch is likely, with
south central SD likely seeing no snowfall. Gusty northwest winds on
Thursday behind the front could produce blowing and drifting of snow
in spots across the plains.

The coldest air will only be here for a brief time, mainly later
Thursday into Friday morning, before rising back to near average
levels for at least Friday afternoon and Saturday. Some unsettled
and colder weather is likely to return for Sunday and into early
next week as a broad trough is progged to dig south across the
western states. Some accumulating snowfall is looking increasing
likely during the period, especially across western and southern
portions of the CWA, as moist southwesterly flow develops and upper
level disturbances pass over the colder air at the surface.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Wednesday Night)
Issued At 1005 PM MST Tue Feb 13 2018

VFR conditions expected through the period. Breezy Southwest
winds will continue over northeast Wyoming and the Black Hills
through Wednesday morning.

&&

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

$$

DISCUSSION...26
AVIATION...JC



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