Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 111056
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
356 AM MST Thu Jan 11 2018

.DISCUSSION...(Today Through Wednesday)
Issued at 209 AM MST Thu Jan 11 2018

Latest upper analysis shows a trough over central North America
with the trough axis currently moving eastward and away from the
forecast area. At the surface, cold high pressure is moving into
the region from the northwest. A tight sfc pressure gradient is
producing gusty northwest winds over the South Dakota side of the
forecast area, which combined with the cold air, is producing very
cold windchill readings this morning. A Wind Chill Advisory has
been issued for far northeastern Wyoming, northwestern South
Dakota and the plains east of the Black Hills, until 1100 AM MDT
this morning. The winds will diminish some this afternoon but cold
temperatures will remain, with the afternoon highs ranging from
the lower 20s over parts of northeastern Wyoming and the Black
Hills, the the single digits above zero over northwestern South
Dakota.

The next shortwave system and a cold front will affect the area
tonight into Friday. Light snow or flurries will fall over much of
the area, however accumulations will be minimal, with less than an
inch at most locations. Cold weather will persist through Friday,
with a gradual warm up from Saturday into Sunday, ahead of the
next cold front. An upper shortwave trough on the west side of the
Hudson Bay low will swing southward across the northern plains
Sunday night bringing colder air back into the region and some
light snow or flurries. The colder air may be relatively short-lived
early next week before temperatures rise back to near average
levels by midweek.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Friday Morning)
Issued At 343 AM MST Thu Jan 11 2018

MVFR ceilings over northeastern WY and south central SD will
improve to VFR this morning, and breezy northwesterly winds over
the SD plains will gradually dissipate today. MVFR conditions
will return after midnight, as some light snow spreads over the
area.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Chill Advisory until 11 AM MST this morning for SDZ001-002-
     012>014-031-032-073.

WY...Wind Chill Advisory until 11 AM MST this morning for WYZ071.

&&

$$

DISCUSSION...10
AVIATION...Pojorlie



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