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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
303 am MDT sun Aug 2 2015

Short through Monday night
issued at 303 am MDT sun Aug 2 2015

Broad upper ridging will remain across the western Continental U.S. Today. Large
scale subsidence and dry air in place will keep skies mostly sunny
today. NE winds will develop through the day...becoming east/southeast
tonight as return flow sets back up over the County Warning Area. Highs will reach
the middle 80s to middle 90s. Theta-E advection will develop across the
area Monday as return flow increases. The Black Hills into SW South Dakota
may see isolated storms Monday afternoon...however chances will increase
into the evening and continue into Tuesday ahead of a strong wave
crossing the northern to central rockies. Best chance for overnight
storms will be across portions of NE Wyoming...through the Black Hills area
into SW/scntrl South Dakota.

Long term...Tuesday through Saturday
issued at 303 am MDT sun Aug 2 2015

Chance for thunderstorms increase this week...with best
chance coming Tuesday into Wednesday. 00z models continue to show
upper impulse knocking down ridge Tuesday/Tuesday night. Slight
differences with GFS/ECMWF/Gem...tracking surface low across
southern South Dakota/Nebraska. 00z NAM much stronger with surface
to 700mb low than the other models. It appears NAM is suffering with
convective feedback it dumps 6+ inches of rain over the
Black Hills. Area will be primed for thunderstorms as low level
easterly flow increases bl moisture and middle level moisture surges
northward from the southwestern U.S. Cape/shear suggest marginal
severe storms possible Tuesday...but main threat will be locally
heavy rain. Went with cooler temperatures for highs
Tuesday/Wednesday with abundant cloud cover/precipitation.

Thunderstorm chances continue into the weekend. GFS/European model (ecmwf) bring next
upper trough through the northern plains Thursday. Flat upper ridge
then sets over The Rockies as trough moves into the western Continental U.S..
several weak shortwaves move over the ridge into the northern


Aviation...for the 12z tafs through 12z Monday morning
issued at 303 am MDT sun Aug 2 2015

VFR conditions expected through tonight.


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


Short term...13
long term...7

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