Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 142301

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
501 PM MDT Fri Jul 14 2017

.DISCUSSION...(This Evening Through Friday)
Issued at 123 PM MDT Fri Jul 14 2017

Surface analysis shows low over southeast MT with trof extending
southward across eastern WY. Warm front is lifting through
western SD and temps already near or at 100F across many plains
locations. Upper level energy can be seen on water vapor across
WY. The beginning of TSRA already forming across northeast WY
around the Gillette area along the surface trof.

Surface low and associated trof will track east tonight and will
be the main focus for TSRA into this evening, with best chances
for activity from northeast WY through the Blkhls into northwest
SD. MLCAPE values are 500-1500J/KG but shear is quite weak to
sustain rotating updrafts. However, DCAPE close to 2000J/KG would
support gusty winds so that will be the main severe threat from
any storms that develop. Activity should then dissipate late in
the evening as it tracks further east onto the SD plains.

Less instability will be available on Saturday with e/se boundary
layer flow with surface high building into the upper midwest. Best
chances for any storms would be northeast WY into the Blkhls.
Temps will likely be a degree or two cooler.

The hottest day should be Sunday as a surface front moves into far
western SD, with thermal ridge peaking overhead. Again, best
chances for storms from northeast WY into the Blkhls.

Upper ridge expected to flatten early next week with westerly flow
aloft for much of the week. This will result in a slight cool down
along with better chances for storms through the week as short
wave energy moves through the westerly flow.


.AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening)
Issued At 500 PM MDT Fri Jul 14 2017

Isolated to scattered thunderstorms are expected through mid
evening over northeastern Wyoming, the Black Hills, and
northwestern South Dakota. MVFR conditions and gusty winds will be
possible with these storms. Otherwise VFR conditions expected
through the period.


Issued at 123 PM MDT Fri Jul 14 2017

Hot weather expected through the weekend. Best chances for
thunderstorms will be from northeast WY into the Blkhls. Sunday
will be the hottest and driest day with minimum relative humidity
down into the teens and breezy southerly winds creating very
elevated fire wx concerns.




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