Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 152118
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
218 PM MST Thu Feb 15 2018

.DISCUSSION...(This Evening Through Thursday)
Issued at 152 PM MST Thu Feb 15 2018

Upper level analysis has broad trof sliding across the northern
Plains with weak shortwave crossing the CWA at the moment. Skies
are cloudy with light snow still falling from the Black Hills
east. At the surface, arctic cold front has moved south of the
area with temperatures steadily falling through this afternoon.
North winds behind the front have been very brisk, with gusts to
40 mph across the South Dakota plains.

Light snow will continue to diminish and shift east this
afternoon. Gusty northerly winds will also slowly diminish through
the remainder of the afternoon. Temperatures will continue to fall
into the evening hours.

Arctic high pressure will slide across the Black Hills area by
midnight and shift south east by early Friday morning. Skies will
become partly cloudy to clear across the area overnight.

After a relatively chilly morning on Friday, temperatures will
warm back up into the 30s as WAA develops. A weak shortwave and
cold front will cross the area Friday night into Saturday morning
bringing a brief period of snow, with little accumulation. The
rest of Saturday into Saturday night will be dry, with
temperatures in the 30s again on Saturday.

A large upper trof will dive into the Pacific Northwest on Sunday
as a strong and quick moving shortwave skirts the northern
portions of the CWA. The associated surface low will drag another
arctic front through the area Sunday morning, bringing another
round of light snow to the area, along with colder temperatures.
Later Sunday night, the next upper shortwave ejects out of the
central Rockies into the northern Plains. Strong forcing
associated with the upper trof may bring wrap around precip into
the CWA through Monday. Much of the area should see snowfall, but
models still differ a bit on where the heaviest band of snow will
fall. Both the GFS/ECMWF are showing the potential for a swath of
5 to 10 inches across the area. Cool and dry weather is expected
toward the middle of next week.


&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1021 AM MST Thu Feb 15 2018

Widespread MVFR conditions in light snow will occur across the
region through this afternoon. Areas of IFR conditions with LIFR
conditions in SN will occur on the plains east and southeast of
the Black Hills this afternoon along the cold front pushing
southeastward across the area. Gusty northwest winds will occur
this afternoon, decreasing toward evening. Snow will end and conditions
will improve to VFR early this evening as drier and colder air
flows into the region.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 6 PM MST this evening for SDZ001-
     002-012>014-024>026-031-032-072-073.

WY...Winter Weather Advisory until 6 PM MST this evening for WYZ054-
     056-057-071.

&&

$$

DISCUSSION...15
AVIATION...10


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