Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 141124

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
524 AM MDT Tue Aug 14 2018

.DISCUSSION...(Today Through Monday)
Issued at 401 AM MDT Tue Aug 14 2018

Current upper level analyses has complex flow across the area,
with closed low over Kansas, weak ridge over the southwest, and
trof dropping south across the northern Rockies. Skies are partly
to mostly cloudy across the forecast area, with showers and
thunderstorms across northeast Wyoming into far western South
Dakota. At the surface, high pressure is located across southern
Saskatchewan, with weak surface low just east of Pierre.
Temperatures at 4 am are in the 50s to lower 60s.

Weak shortwave energy will continue to move across the area in
west to southwest flow just ahead of the main trof in Montana.
Showers and thunderstorms are expected much of the day across
northeast Wyoming and far western South Dakota. Temperatures will
be cooler today, in the 70s to lower 80s under partly to mostly
cloudy skies.

A stronger shortwave with the main upper trof will bring better
chances for precipitation to the area tonight into Wednesday
morning, along with continued cool temperatures. Best chances for
precip will be across northeast Wyoming, the Black Hills, and
across souther portions of South Dakota. Rainfall amounts with
this system will range from a tenth of an inch, up to a half inch
in some locations. Lows tonight will be in the 50s to around 60
degrees, and highs on Wednesday will be in the 70s to lower 80s.

Models are showing another upper ridge building over the western
states for the end of the week, but both the GFS and ECMWF are in
agreement on another shortwave breaking down this ridge by the
weekend. Highs for the latter half of the week will be in the 80s.


.AVIATION...(For the 12Z TAFS Through 12Z Wednesday Morning)
Issued At 521 AM MDT Tue Aug 14 2018

VFR conditions are expected through the TAF period, although some
areas of smoke may lower the visibility to less than 10 miles at
times. Isolated thunderstorms will move across the northern third
this morning. Another impulse will bring a good chance of TS to
NE WY late this afternoon and evening, with activity pushing east
into western SD tonight.




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