Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 202056

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
256 PM MDT Sun Aug 20 2017

.DISCUSSION...(This Evening Through Sunday)
Issued at 256 PM MDT Sun Aug 20 2017

Upper air analysis shows zonal flow across much of the northern
CONUS with a series of weak waves cross the central third of the
country. One of these waves brought showers to parts of northwest SD
earlier the morning. Surface analysis shows high pressure centered
across the Dakotas with mostly sunny skies across the area with
highs in the 70s to low 80s.

An overall quiet evening is expected...with increasing clouds. Short
range models are not agreeing very well with how storms may end up
developing this evening ahead of a very weak wave...though latest
trends show storms popping up across the southern Black Hills/SW SD
area. Good theta e advection will develop tonight as southeast
return flow sets up. Storms will develop ahead of another wave late
tonight over NW SD and push into better theta e air through the
western SD plains into Monday morning...then south central SD late
Monday morning into the early afternoon. Clouds across western SD
will likely be an issue for the eclipse...most most likely closer to
central SD. It`s looking better approaching the Black Hills
area...and into northeast WY. Highs will be in the mid 70s to mid

Drier weather is expected Tuesday and Wednesday with highs pressure
across the northern plains and upper ridging building over the
northern Rockies. More active weather is expected toward the second
half of the week as the next upper trough approaches from the
northwest CONUS. Temperatures near seasonal averages will continue.


.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1128 AM MDT Sun Aug 20 2017

Weak high pressure will remain over the region today. Another
impulse will bring ISOLD-SCT SHRA/TS to far southern areas later
tonight. Local MVFR conds possible in TS. MVFR stratus is likely
to develop over scentral SD Monday morning and may persist into
early Monday afternoon.




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