Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 182336

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
536 PM MDT Wed Oct 18 2017

.DISCUSSION...(This Evening Through Wednesday)
Issued at 241 PM MDT Wed Oct 18 2017

Upper level analysis has fast moving upper trof across central
Canada, with ridge rebuilding across the western CONUS. Skies are
mostly clear across the Northern Plains with just some
intermittent cirrus streaming across the area. At the surface,
high pressure has moved into the Northern Plains, with the weak
cold front now well south and east of the area. Lee trof is
quickly redeveloping across Wyoming and Montana. Temperatures
across the area are in the 60s with north winds across central SD
and southerly winds developing across northeast WY.

Upper ridge will rebuild for the latter half of the week, and
strong southwesterly boundary layer flow will help temperatures
climb into the 70s and 80s. The next upper trough will move into
the region Friday night, bringing chances for light rain/snow
showers into Saturday. Some instability across south central SD
may allow for a few thunderstorms there. Saturday will be breezy
with highs cooling to the 50s and lower 60s. Sunday will be a
little warmer as shortwave ridging slides across the area. Both
medium range models are now showing a secondary wave possibly
producing a few showers Sunday night into Monday. Nonetheless,
both models agree on another large ridge building over the western
CONUS for the middle of next week.


.AVIATION...(For the 00Z TAFS Through 00Z Thursday Evening)
Issued At 534 PM MDT Wed Oct 18 2017

VFR conditions will continue through the period.


Issued At 241 PM MDT Wed Oct 18 2017

Minimum RH could fall below 15 percent, and gusty southwesterly
winds could approach 30 mph across parts of northeastern WY on
Thursday. This may result in critical fire weather conditions.
Have expanded the Fire Weather Watch to all northeastern Wyoming
fire weather zones for Thursday afternoon.


WY...Fire Weather Watch from Thursday morning through Thursday
     afternoon for WYZ259-297>299.



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