Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 252031

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
231 PM MDT Tue Jul 25 2017

.DISCUSSION...(This Evening Through Tuesday)
Issued at 203 PM MDT Tue Jul 25 2017

Latest analysis shows an upper low over Manitoba moving eastward
through a broad ridge that covers much of North America. This is
producing southwesterly flow aloft over the forecast area with a
shortwave approaching the forecast area. Multiple surface
boundaries combined with the shortwave, will lead to widespread
showers some thunderstorms this afternoon and tonight. A surface
boundary lying diagonally from SW-NE across south central South
Dakota will be the focus for possible severe thunderstorm
development. As moisture pools along the boundary, MUCAPE has
risen to 2500-3500J/KG. Could see some training storms and/or
locally heavy rain, especially with light steering winds.

On Wednesday and Thursday, the upper ridge will begin to rebuild
over the western CONUS. Temperatures will be slightly cooler than
on previous days with the chance for showers and storms, mainly
over northeastern Wyoming and far western South Dakota.

Friday through Sunday, the upper ridge will build over the high
plains with warmer temperatures and small chances for thunderstorms.


.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 203 PM MDT Tue Jul 25 2017

Thunderstorms are expected to develop across much of the area
this afternoon and overnight. MVFR conditions will be possible in
storms, otherwise VFR conditions are expected.




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