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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
152 PM MDT Wednesday Oct 1 2014

Short term...this evening through Thursday night
issued at 150 PM MDT Wednesday Oct 1 2014

Upper level wave is moving through Wyoming...continuing to
produce showers across northeast Wyoming and far western South Dakota. Fairly
tight pressure gradient is causing some breezy northwest winds
across the County Warning Area...especially in northwest South Dakota.

Light showers will transition eastward across southern South Dakota
tonight...and clouds will dissipate. Winds will become light...and
lows will be in the middle 30s to middle 40s.

A fast-moving Canadian low pressure system will sweep a cold front
through the northern plains on Thursday. Winds will become gusty
from the northwest Thursday afternoon into the evening. The mav
reaches Wind Advisory criteria across northwest South Dakota...but as usual it
is stronger than the other models. Highest pressure rises of 7-8
mb/3hr slide west of the usual windy areas and increase after
sunset...so at this point a Wind Advisory seems marginal. However
with the cold advection following the front...30-40kt 850mb
winds...and if models come into better agreement...later shifts may
decide to issue one.

Also following this cold front will be a chance for showers...mainly
across northeast Wyoming and far western South Dakota. These will be aided by upper
level divergence associated with the left exit region of the jet. As
temperatures cool Thursday night...some of the lingering showers may be in
the form of snow. Minimal accumulations are expected.

Temperatures on Thursday will be tricky with the timing of the cold
front. Middle 50s are in the forecast for northeast Wyoming and northwest
South Dakota...with middle 60s across south central South Dakota. On Thursday night...lows
will range from the 20s across the Black Hills...northeast Wyoming...and
northwest South Dakota...to the middle 30s over south central South Dakota. Frost/freeze
headlines may be necessary across central South Dakota where temperatures have not
dipped that low yet this season.

&&

Long term...Friday through Wednesday
issued at 150 PM MDT Wednesday Oct 1 2014

Upper ridging will build across the western Continental U.S. As
the large upper trough shifts into the Midwest. Little change to the
pattern is expected through the remainder of extended as the
longwave pattern becomes a bit persistent. Northwest flow over the
area will bring dry weather with some passing middle/high clouds.
Temperatures will be below average Friday...but then warmer air
advects in through the weekend with near average temperatures through early
next week. Occasional shortwaves will slide over the ridge...which
will bring breezy days to the area. Right now it looks like Friday
will be the windiest day in the extended period.

&&

Aviation...for the 18z tafs through 18z Thursday
issued at 150 PM MDT Wednesday Oct 1 2014

Isolated to scattered showers are expected across
northeast Wyoming and far western South Dakota this afternoon...then
spreading into south central South Dakota tonight. MVFR ceilings/visibility
are expected with any showers that develop. IFR ceilings are possible
with any shower development near the Black Hills. Breezy northwest
winds will persist through early evening across the
plains...especially across the South Dakota plains.

&&

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

$$

Short term...pojorlie
long term...15
aviation...15

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