Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 282055

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
255 PM MDT TUE JUN 28 2016

.SHORT TERM...(This Evening Through Wednesday Night)
Issued at 255 PM MDT Tue Jun 28 2016

Current surface analysis shows low pressure over northeast WY,
with frontal boundary extending south across eastern WY and the
lee of the CO Rockies. Upper level analysis shows high pressure
centered over eastern UT, with ridge extending north across the
Northern Rockies. Weak shortwave noted on water vapor imagery
crossing southeast MT and eastern WY, moving southeast through our
area late this afternoon and evening. Instability is rather strong
to the east of the boundary, with cape values of 2000 to 3000 j/kg
currently from far northeast WY to southwest SD. A few storms
developed over the Black Hills around midday, but struggled to
move off the hills with strong cap in place. Cap is eroding now
across the plains and more robust storms are developing across
northeast WY ahead of the shortwave. Temps are in the 80s to
around 90 degrees with southeasterly winds at most locations,
especially to the east of the boundary.

Active weather is expected across a good portion of the cwa over the
next few hours, especially from northeast WY through southwest SD.
Strong to severe storms can be expected with large hail and strong
wind gusts the main threats. An isolated tornado cannot totally be
ruled out, but the threat looks to be rather low with low level
shear on the weaker side. The stronger storms should shift toward
southern portions of northeast WY and southwest SD by early evening,
with most of the stronger activity moving south-southeast out of the
cwa by mid evening. Isolated showers and storms will likely linger
across the area overnight, especially across southern SD. Lows
will be in the mid 50s to lower 60s.

Wednesday will see more showers and thunderstorms across the area,
mainly during the afternoon and evening hours, as another shortwave
rotates across the area. At this point, the threat for severe storms
looks to shift a bit further south, but will still cover most of the
Black Hills area and much of the southwest SD plains. Hail and wind
will be the main threats again. Temps will be a bit cooler, with
highs mostly in the 80s across the plains, 70s in the Black Hills.
Activity should become more isolated again overnight, with lows in
the mid 50s to lower 60s.

.LONG TERM...(Thursday Through Tuesday)
Issued at 255 PM MDT Tue Jun 28 2016

Progressive westerly to northwesterly upper level flow will
continue through the extended period with relatively moist
southeasterly upslope flow at the lower levels. As a series of
disturbances push through the area, the persistent flow of low/mid
level moisture will aid in the development of diurnal convection
nearly every day. Most days the coverage will be limited, with
only isolated to scattered thunderstorms. Deep layer shear aloft
will support the threat of severe storms; however, the lack of
strong upper level forcing will keep the coverage of severe storms
limited. Temperatures will remain slightly warmer than average,
with highs mainly in the 80s through the weekend leading into a
more significant warm-up early next week.


.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 255 PM MDT Tue Jun 28 2016

Scattered to numerous thunderstorms this afternoon and evening.
Some thunderstorms may be severe this afternoon and early evening,
with large hail and damaging wind gusts. VFR conditions will
prevail through the period except for local MVFR conditions near
any thunderstorms.


.UNR Watches/Warnings/Advisories...


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