Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 182315

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
515 PM MDT Fri Aug 18 2017

.DISCUSSION...(This Evening Through Friday)
Issued at 218 PM MDT Fri Aug 18 2017

Upper trough is sitting across the eastern half of the CONUS with
weak ridging across the northern Rockies into the northern High
Plains. At the low levels...northwest flow on the backside of the
low pressure across Great Lakes. Satellite shows mostly clear skies
across the region with temperatures in the upper 70s to upper 80s.
Quiet weather will continue tonight with clear skies and lows in the
50s. Upper ridge will weaken Saturday but remain over the northern
plains. Surface trough/weak cold front will cross the area Saturday
afternoon. Warm air advection early tomorrow will result in
temperatures rising into the mid 80s to upper 90s. Cooler temps will
then return as the frontal boundary crosses the area late Saturday
into the evening. Storms are not expected tomorrow with the very dry
low levels...but can`t rule out a storm or two developing in the
afternoon across the Black Hills.

Surface high will slide east of the area Sunday with return flow
bringing higher theta e back into the area. However not enough for
storm development aside from an isolated storm or two. Models are
progging an upper wave to cross northwest to west central SD with
a few showers or weak storms...but overall looks to be a weak
event. Can`t rule out a storm or two becoming strong. A shortwave
trough will cross the region Monday mainly in the afternoon and
evening. Some mid to high clouds are expected midday Monday...with
perhaps low clouds near central SD. Storms will develop mainly
across the Black Hills and the western SD plains. Relatively dry
weather is expected for the rest of the week with isolated chances
for showers and storms. Highs will generally be in the 80s.


.AVIATION...For the 00Z TAFS Through 00Z Saturday Evening
Issued At 513 PM MDT Fri Aug 18 2017

A few clouds over the area will dissipate this evening and skies
will be mostly clear through Saturday. A low pressure trof over
eastern MT and WY will slowly cross the area, with southeast
winds over SD and winds becoming NW behind it.




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