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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
451 am MDT Thursday Jul 30 2015

Short term...today through Friday night
issued at 212 am MDT Thursday Jul 30 2015

08z surface analysis had weak high pressure over the County Warning Area with a
trough across Mt/ND. This trough will shift south through the County Warning Area
today in response to shortwave energy moving across southern sk
into the upper Midwest. Main effect will be a slight increase in
winds. Subsidence under right entrance region of 70kt jet streak
over the Central Plains will promote subsidence and mlcin high
enough to prevent convection along boundary. Temperatures this
afternoon near guidance.

Tonight/Friday...upper ridge over the western Continental U.S. Continues to
build with thermal ridge expanding eastward. Tail end of
aforementioned boundary will swing back north across southwest
portions of County Warning Area Friday afternoon with weak 700-850mb Theta-E ridge.
Could see isolated afternoon -tsra rooted over the higher terrain
with about 500j/kg MLCAPE...but mlcin will be notable and shortwave
forcing will be scant at best. Temperatures near guidance.

Long term...Saturday through Wednesday
issued at 212 am MDT Thursday Jul 30 2015

Drier west to northwest flow aloft will remain across the region
through the weekend. Isolated showers and thunderstorms will be
possible Saturday over far southwest into south central South Dakota. Temperatures
will be slightly above average through the weekend...with highs in
the 90s across the plains...80s in the Black Hills.

The weather pattern could become more unsettled early next week as
east to southeast winds bring increasing moisture...and weak upper
level disturbances pass through the area. Models are in disagreement
on the timing of these waves...with the European model (ecmwf) suggesting more
activity then the GFS. Although there is plenty of
uncertainty...Tuesday into Tuesday night still appear to have a
better chance of storms...as well as towards the end of the week.
Temperatures will be slightly cooler early next week...but still around
average.

&&

Aviation...for the 12z tafs through 12z Friday morning
issued at 451 am MDT Thursday Jul 30 2015

VFR conditions expected through tonight.

&&

Unr watches/warnings/advisories...
South Dakota...none.
Wyoming...none.
&&

$$

Short term...helgeson
long term...pojorlie
aviation...pojorlie

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