Area Forecast Discussion
Issued by NWS Rapid City, SD

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473
FXUS63 KUNR 221136
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
536 AM MDT Mon May 22 2017

.DISCUSSION...(Today Through Sunday)
Issued at 147 AM MDT Mon May 22 2017

Cyclonic upper flow will continue over the area today as the low
pressure system remains over swrn Ontario and a series of
disturbances across the northern plains as an upper trough rotates
across the region today. Mid level CAA through much of the day
combined with diurnal heating will generate enough instability for
scattered-numerous showers and isolated thunderstorms today,
ending this evening. Windy conditions are expect over most of the
forecast are today, esp over parts of northeastern Wyoming this
afternoon, with wind gusts enhanced with deep mixing as the
showers pass through. Showers, clouds, and cool thermal fields
will support below normal temps once again with highs on the
plains mainly in the 50s. Shortwave ridging will affect the area
on Tuesday, with perhaps a lingering shower early over south
central SD. Dry and warmer weather can be expected midweek before
the next trough arrives toward the end of the work week.

Large scale flow is trending toward blocking by next weekend per
western NOAM sustained ridging, which would stall or support slow
eastward progression of the expected NW CONUS upper trough/closed
low. This would leave the region in unsettled cyclonic flow for
potentially several days akin to GFS and CMC solutions. Therefore,
expect a return to cool conds after Thur, with chances for precip
returning to the area. It is quite possible that temps will
verify even cooler than current forecast numbers in this period.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Tuesday Morning)
Issued At 529 AM MDT Mon May 22 2017

Mainly VFR conditions expected through the period. Scattered
-SHRA/isolated TS are expected through early evening with local
MVFR conditions. Gusty northwest will persist through early
evening.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION...10
AVIATION...15



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