Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 241722
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1122 AM MDT TUE MAY 24 2016

.SHORT TERM...(Today Through Wednesday Night)
Issued at 310 AM MDT Tue May 24 2016

Current surface map high pressure across Montana with weak trof
from northeast to southwest South Dakota. Mostly clear skies
across the forecast. Upper low continues to spin across southern
Saskatchewan with shortwave moving through eastern Dakotas.
Another upper low is located over California. Sunny skies and
rapid warmup in store for the area this morning, then becoming
very active this afternoon and evening. Short range models in very
good agreement with shortwave lifting through eastern Wyoming into
western South Dakota with strong lift enhanced by right entrance
region of jet streak across North Dakota. Convective allowing
models show widespread thunderstorms late this afternoon into the
evening hours. The biggest issue will be return of low level
moisture and amount of instability. Surface dewpoints currently in
the 30s to lower 40s across the forecast area. Latest RAP/NAM
bring some lower 50 dewpoints into southwest South Dakota this
afternoon, while HRRR maintains lower to mid 40 dewpoints. With
lack of stronger return flow until this afternoon, RAP/NAM may a
little on the high side. Either way, the best instability will be
along southern portions of forecast area. Sufficient shear for
supercells, especially from southern Black Hills/Southwest South
Dakota. Bulk of convection should move north and east of the
forecast area after midnight. Upper low shift into eastern Montana
on Wednesday. Steep mid level lapse rates with marginal Boundary
layer moisture will result in scattered showers/thunderstorms.

.LONG TERM...(Thursday Through Monday)
Issued at 310 AM MDT Tue May 24 2016

Persistent upper level troughing over the northwest
CONUS will keep active southwest flow across the Northern Plains
through the Memorial Day weekend. Periodic shortwave energy will
eject out of the trough, keeping a daily chance of showers and
thunderstorms in the forecast through the holiday weekend.
Temperatures will be near seasonal averages, with highs each day in
the mid 60s to upper 70s. Lows at night will be in the 40s to mid
50s.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1120 AM MDT Tue May 24 2016

Showers and thunderstorms will develop across the area this
afternoon into the evening. Some strong storms will be
possible...mainly near the Nebraska border. MVFR/IFR conditions
will be possible near any precipitation.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

SHORT TERM...7
LONG TERM...15
AVIATION...13



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