Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 151701

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1101 AM MDT Wed Aug 15 2018

.DISCUSSION...(Today Through Tuesday)
Issued at 347 AM MDT Wed Aug 15 2018

Current upper level analysis has compact closed low moving into
northeastern Wyoming, with ridging over the Northern Rockies.
Local radar has showers and thunderstorms over southwestern SD at
the moment. At the surface, high pressure is located across
eastern ND, with winds light and variable across the area.
Temperatures at 3 am are in the 50s to lower 60s.

Unsettled weather will continue today as the upper closed low
slowly moves across the forecast area. Shower and storms will
continue to develop and move across southern portions of SD this
morning, with additional storms developing this afternoon as
instability increases. The best instability late this afternoon
and evening will be across the Black Hills and far southern SD,
with around 1000 to 1500 j/kg MUCAPE. Shear is rather marginal
across southern SD, but with great dynamics and ample CAPE, a few
strong to severe storms will be possible across southern and south
central SD this afternoon, with large hail and strong wind gusts
the main threats. With precipitable water values 115 to 120
percent of average, there will be a small chance of locally heavy
rainfall with stronger storms today and tonight.

The upper low will shift east on Thursday as the western ridge
builds into the Northern Plains. Mainly dry conditions are
expected with temperatures returning to near average. Warm and dry
conditions will persist into Friday.

Another fairly strong upper level system for this time of year will
move across the area over the weekend, bringing good chances for
showers and storms Saturday and Sunday. There is potential for some
severe storms and heavier rainfall across at least portions of the
area. That system will exit early in the week, with some drier
weather returning for the first half of the week.


.AVIATION...(For the 18Z TAFS Through 18Z Thursday)
Issued At 1100 AM MDT Wed Aug 15 2018

Scattered showers and thunderstorms are expected today with local
MVFR/IFR conditions, mainly in the Black Hills and south central
South Dakota. Outside of any showers or thunderstorms, VFR
conditions are expected through the period.




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