Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 212318
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
518 PM MDT SUN AUG 21 2016

.SHORT TERM...(This Evening Through Monday Night)
Issued at 242 PM MDT Sun Aug 21 2016

Upper ridge across the wrn CONUS continues to build across the nrn
plains today. Surface analysis shows high pressure has moved into
the MS valley...with return flow across the cntrl/nrn plains. Temps
have reached the 80s across most areas. Clear skies will continue
tonight with lows dropping into the 50s to low 60s...warmest across
scntrl SD where the LLJ will be strongest tonight. Breezy SW
downsloping winds are also expected to develop late tonight across
the nrn/nern Foothills. Thermal ridge will cross the region Monday
ahead of the next trough crossing the nrn Rockies. Highs will reach
the 90s to lower 100s across the plains...and 80s/low 90s over the
BH. Breezy W/SW winds will develop across SCntrl/SW SD into parts of
the ne WY plains. Lows Mon night will drop into the 50s across ne WY
to upper 60s over scntrl SD.

.LONG TERM...(Tuesday Through Sunday)
Issued at 242 PM MDT Sun Aug 21 2016

Upper trough moving from southern AB into ND will push a cold
front through the area Tuesday morning. Gusty northwest winds are
expected behind it with near advisory winds possible on the east
side of the Black Hills over the normal squeeze areas.
Temperatures will be tricky given cold air advection.

Upper trough moves into the Great Lakes Wednesday and Thursday with
moisture slowly returning to the CWA. A couple of weak disturbances
will move through bringing chances for showers and thunderstorms.
Temperatures will be noticeably cooler.

Westerly flow aloft develops Friday and then southwesterly for the
weekend allowing thermal ridge to slowly build back into the CWA
supporting a warming trend.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 516 PM MDT Sun Aug 21 2016

VFR conditions with mostly clear skies will continue tonight and
on Monday. Low level wind shear will develop over the SD plains,
including KRAP, after 06Z, ending by 12Z.

&&

.FIRE WEATHER...
Issued At 242 PM MDT Sun Aug 21 2016

An upper level and thermal ridge will peak Monday bringing a
deeply mixed boundary layer and very dry minimum relative humidity
values. Readings from 10-15% are expected across the southwest
third of the area Monday afternoon and evening with 15-25% across
the rest of the region. With mixing heights approaching 9- 14Kft
AGL, suspect momentum transfer will be maximized with gusty west
to southwest winds possible across the far southwest. Will hoist
fire weather weather watch to highlight potential Monday afternoon
and early evening.

A cold front will slice through the area Tuesday with gusty
northwest winds on the SD plains most of the day. Minimum relative
humidities around 20% will preclude headlines at this point, but if
air comes in drier this thinking may need to be reassessed.

&&

.UNR Watches/Warnings/Advisories...
SD...Fire Weather Watch from Monday afternoon through Monday evening
     for SDZ263.

WY...Fire Weather Watch from Monday afternoon through Monday evening
     for WYZ259-298.

&&

$$

SHORT TERM...13
LONG TERM...Helgeson
AVIATION...10
FIRE WEATHER...Helgeson



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