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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
513 PM MDT Tuesday Sep 2 2014

Short term...this evening through Wednesday night
issued at 150 PM MDT Tuesday Sep 2 2014

Water vapor shows transitory upper ridge building through the northern
rockies into the northern plains...with upper trough working into the Pacific
northwest. At the surface...weak trough located just east of the Black Hills. Mostly
sunny skies overhead with warm temperatures in the 70s to lower 80s early
this afternoon.

Sharp upper trough works across southern Saskatchewan/Montana on Wednesday and southern Manitoba/ND
Wednesday night. Thermal ridge noses into the County warning forecast area ahead of this trough
resulting in very warm temperatures...especially south/east of the Black Hills
where temperatures will push into the lower 90s. Dry conditions expected
with strong cap in place.

Robust cold front will then push through the County warning forecast area Wednesday night. 6+mb/3hr
pressure rises and 40-50kt 850mb winds will result in a period of
gusty winds behind the front...and wind highlights may become
necessary. There will be some elevated instability and weak
Theta-E advection on the plains of western/central South Dakota overnight ahead of
the front...but given limited moisture will continue with a dry
forecast.

&&

Long term...Thursday through Tuesday
issued at 150 PM MDT Tuesday Sep 2 2014

An upper trough will cross ND/southern Canada Thursday...
with the best forcing remaining north/NE of the area. This will keep dry
weather across the area...with temperatures well below average Thursday and
into Friday. Could see lows fall into the 30s in a few areas Friday
morning. High pressure will dominate the upper Midwest into the
Great Plains for the end of the week...with return flow setting up
across the region. Warmer air will bring temperatures back to near average
over the weekend with dry conditions likely continuing.

As a broad upper trough moves into the western states early next
week...southwesterly flow will develop over the High Plains. Could
see at least isolated shower and thunderstorm activity returning by
early next week...with a gradual cooldown into the middle of next
week. Will keep slight chances for showers and storms over mostly
southern portions of the area late Sunday into early next week.

&&

Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 511 PM MDT Tuesday Sep 2 2014

VFR conditions through the forecast period. A low level jet will develop
over scentral South Dakota in response to an advecting northwest Continental U.S. Upper
trough. Expect breezy southerly winds there tonight through Wednesday
morning.

&&

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

$$

Short term...Johnson
long term...26
aviation...jc

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