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fxus63 kunr 231139 

Area forecast discussion for western South Dakota and northeastern Wyoming
National Weather Service Rapid City South Dakota
539 am MDT Sat Sep 23 2017

Discussion...(today through friday)
issued at 221 am MDT Sat Sep 23 2017

Water vapor imagery shows deep upper trof across the western
Continental U.S. With southwest flow across The Rockies into the northern
plains. Scattered thunderstorms continue across south central
South Dakota with area of showers across the Black Hills into
northwest South Dakota. Models in decent agreement through Monday
with timing/placement of precipitation across the forecast area.

For today, shower/thunderstorm coverage will diminish this morning
as initial impulse lifts north of the area. Next shortwave lifts
out of The Rockies this afternoon/tonight. Warm air advection/850-700mb Theta-east
advection spreads across western South Dakota resulting in
widespread precipitation. With steep lapse rates, embedded
thunderstorms expected across southwest/south central South
Dakota. Highs 15-20f below average today. Temperatures marginally
cold enough late tonight for rain/snow mix in the higher
elevations of Black Hills.

Upper trof lifts into the northern plains Sunday-Sunday night
with cool temperatures and showers continuing. Temperatures aloft
a few degrees cooler Sunday night for better chance of snow in
the higher elevations of the Black Hills. Upper trof slide east of
the area Monday-Tuesday...with drier northwest flow across the
forecast area. A slow warmup in temperatures, with temperatures
still below average through mid week.


Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 538 am MDT Sat Sep 23 2017

MVFR to IFR conditions will continue across much of the area
through the forecast period as rain showers continue. LIFR
conditions will be possible at times...particularly across the
Black Hills area.


Unr watches/warnings/advisories...
South Dakota...none.

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