Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 102200
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
300 PM MST Wed Jan 10 2018

.DISCUSSION...(This Evening Through Wednesday)
Issued at 300 PM MST Wed Jan 10 2018

Current surface analysis shows cold front now exiting far
southern and southeastern portions of the forecast area, with much
colder air quickly pushing in behind it. Snow and wind have moved
in behind the front as upper level shortwave moves quickly east
across eastern portions of MT and WY right now. Winds are gusting
to 50 mph in a few areas. KUDX radar shows snow across northeast
WY and much of far western SD, spreading eastward. This will be a
quick hitting system, with snow exiting quickly from west to east
across the CWA this evening. Temps range from the single digits
over parts of northeast WY and far northwest SD to the 30s across
far southern SD.

As mentioned, snow will end rather quickly from west to east this
evening. Snowfall totals of 1 to 3 inches are expected across a good
portion of the advisory area, locally higher amounts still possible
across far northwest SD. The Rapid City area will see a quick burst
of snow for a couple of hours late this afternoon, with less an inch
or less expected. After the snow ends, areas of blowing snow will
persist across the SD plains tonight into Thursday, especially
toward south central SD. Lows tonight will generally be in the 5
below to 5 above range, with wind chills from 10 below to around 25
below late tonight and early Thursday, lowest values across far
northwest SD. A wind chill advisory may eventually be issued for far
northwest SD after the snow ends. Thursday will be cold and dry with
highs ranging from the single digits over northwest SD to the 20s
over the higher elevations of northeast WY and the Black Hills.

The next shortwave system and cold front will move into the area
later Thursday night and Friday. Areas of light snow are expected
with accumulations mostly an inch or less. The best potential for
accumulating snowfall at this time looks to be across northeast WY,
the Black Hills, and possibly northwest SD. Cold weather will
persist into Saturday for most areas with a brief warmup likely on
Sunday ahead of the next cold front. An upper low will swing
southeast across central Canada later in the weekend, bringing
another cold front and shot of arctic air across the Northern
Plains. Some light snow/flurries are possible with the front late
Sunday and Sunday night. Colder air may be relatively short-lived
early next week before temperatures rise back to near average levels
midweek.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Thursday)
Issued At 1051 AM MST Wed Jan 10 2018

A fast moving storm system will cause conditions to continue to
deteriorate this afternoon, before improving again overnight. Snow
and blowing snow will cause widespread IFR and some areas of LIFR
conditions this afternoon and evening. Conditions will improve to
MVFR and VFR overnight as this system moves eastward. Gusty
northwest winds will continue through the forecast period.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 11 PM MST this evening for SDZ001-
     002-012>014-024-025-031-042-072-073.

     Winter Weather Advisory until 5 AM MST /6 AM CST/ Thursday for
     SDZ044-046-047-049.

     Winter Weather Advisory until 2 AM MST Thursday for SDZ032-043.

     Winter Weather Advisory until 8 PM MST this evening for SDZ026-
     030-074.

WY...Winter Weather Advisory until 11 PM MST this evening for WYZ057-
     071.

     Winter Weather Advisory until 8 PM MST this evening for WYZ054-
     056.

&&

$$

DISCUSSION...26
AVIATION...MLS



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