Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 232341

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
541 PM MDT Fri Mar 23 2018

.DISCUSSION...(This Evening Through Friday)
Issued at 115 PM MDT Fri Mar 23 2018

Water vapor shows long wave trof over the western CONUS, with
shortwave embedded in SW flow aloft moving into the Dakotas. At
the surface, main low is centered over eastern CO/western KS with
weaker surface low over the Black Hills. Warm front that surged
through the Black Hills and southwestern SD has allowed temps to
warm well into the 50s and even 60s in those areas, while much
cooler 30s still entrenched across far northwest SD where areas
of fog still persist. Scattered showers have been increasing early
this afternoon with short wave overhead and some modest

Showers expected to cross the region this evening and be most
numerous over south central SD, with precipitation then ending
from west to east overnight. Northwest surface winds expected to
increase behind departing short wave, which should allow the fog
across northwest SD to gradually decrease in coverage.

On Saturday, short wave ridge will cross the Northern Plains and
bring and dry and relatively mild temps to the area. Next short
wave trof rotating around the larger western CONUS trof will bring
another round of showers (possibly mixed with snow) for Saturday

Majority of medium range guidance brings a rather strong northern
stream trof through the Northern Rockies into the Northern Plains
late Sunday into Monday, with a possible closed 700mb low moving
across Northeast WY and Northwest SD. This has the potential to
bring several inches of wet snow to far Northeast WY, Southeast
MT, and far Northwest SD. A watch may become necessary soon in
those areas if models remain consistent, so stay tuned.

A rather persistent northwest flow aloft pattern will likely
develop for mid to late next week, keeping things unsettled.

Temps through the next week should be rather close to average,
with the exception of Monday as northern stream trof brings colder
air and more widespread rain/snow to the region.


.AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening)
Issued At 534 PM MDT Fri Mar 23 2018

Isolated showers across portions of northeastern Wyoming and
western South Dakota will gradually wane this evening. Pockets of
MVFR/IFR conditions are possible in heavier showers. Could see
the development of patchy, thin fog at KRAP and across the South
Dakota plains tonight. Fog chances will increase at KRAP after
8-9z timeframe and could yield IFR/LIFR visibility before
dissipating after 14-15z Saturday morning.

Otherwise, VFR conditions will rule across the area tonight and




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