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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
539 PM MDT Sat Jul 30 2016

Short term...(this evening through Sunday night)
issued at 153 PM MDT Sat Jul 30 2016

20z surface analysis had boundary from central Montana into northeast
Colorado. Ahead of boundary, 1-2kj/kg MLCAPE is developing. Mlcin
eroding, especially over the higher terrain. Cumulus field perking up a
bit from southeast Montana into the Black Hills, which is ahead of a
very subtle shortwave over southeast Mt, indicated by weak altocumulus castellanus
field. With upper ridge building over the County Warning Area per water vapour
matinee, convective potential somewhat lower than yesterday but
severe threat is similar with storms that develop given 15-20m/S
0-6km bulk shear. Cams suggest strong to severe storms to occur
in and near the Black Hills into south central South Dakota where richest
boundary layer moisture exists. Activity will shift southeast
overnight. Temperatures will be near guidance.

Sunday, upper ridge over the northern plains with upper low moving
across south central Canada as tail end shortwave moves across
Mt/ND. Aforementioned boundary shifts east with modest MLCAPE
developing ahead of it over western South Dakota. Mlcin will be higher than
today with enough shear for severe storms if storms develop in the
afternoon and evening. Additional storms will occur Sunday night as
elevated convection on the South Dakota plains pops up late given 25-35kt low
level jet. Temperatures will be near guidance ahead of boundary and
above guidance in the drier air behind it.

Long term...(monday through saturday)
issued at 153 PM MDT Sat Jul 30 2016

Zonal flow aloft early in the week will give way to southwesterly
flow Tuesday and Wednesday as upper level low moves across the
Pacific northwest and eventually into the southern Canadian prairie
provinces. Weak disturbances in the flow will bring mostly
diurnally driven shower and thunderstorm activity Monday and
Tuesday, with the best chances across the Black Hills each
afternoon. Above average temperatures can be expected across much
of the area Monday and Tuesday, before a cold front passage late
Tuesday night and Wednesday brings more seasonable temperatures
for the rest of the week. Drier west-northwest flow late in the
week should bring mostly dry conditions, with just a slight chance
of thunderstorms at this point in some areas for Thursday and
Friday.

&&

Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 533 PM MDT Sat Jul 30 2016

VFR conditions will prevail tonight and on Sunday. Scattered
thunderstorms will be located from northeastern Wyoming, across
the Black Hills and into south central South Dakota during the
early evening. Small hail and strong gusty winds are expected with
the thunderstorms.

&&

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

$$

Short term...helgeson
long term...26
aviation...10

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