Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 230929

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
329 AM MDT Thu Mar 23 2017

.SHORT TERM...(Today Through Friday Night)
Issued at 315 AM MDT Thu Mar 23 2017

Current surface map shows low deepening across eastern Colorado
with inverted trof extending northward along the Wyoming/South
Dakota border. Scattered showers and isolated thunderstorms across
northwest South Dakota in 700-600mb theta-e advection. Upper trof
moving across the western U.S. is beginning to close off in the
Four Corners area. Jet streak rotating out of trof will lifts into
western South Dakota today. Increasing lift with steep mid level
lapse rates will result in increasing coverage of precipitation
today, especially across northeast Wyoming and far western South
Dakota. Sufficient instability for a few thunderstorms across
portions of south central South Dakota late this afternoon/early
evening. As upper low tracks into the central plains on Friday,
focus for precipitation shifts southward tonight and Friday. As
precipitation ends over northeast Wyoming and Black Hills tonight,
thermal profiles support change over to snow. Could be a light
dusting of snow for the Black Hills

.LONG TERM...(Saturday Through Wednesday)
Issued at 315 AM MDT Thu Mar 23 2017

Progressive pattern will continue for the weekend into next week. Shortwave
ridging will result in dry and mild conditions for Saturday. Chance
for precipitation will return Saturday night and Sunday with next
trof. Another upper trof to impact the area Tuesday/Wednesday.
GFS/GEM/ECMWF trending towards a splitting flow, with closed low
over the southwestern CONUS and weaker/faster northern stream trof
crossing the northern plains.


.AVIATION...(For the 12Z TAFS Through 12Z Friday Morning)
Issued At 315 AM MDT Thu Mar 23 2017

Widespread showers expected across northeast Wyoming and western
South Dakota today. Ceilings will continue to lower this morning,
especially over northeast Wyoming and northwest South Dakota this
morning. By late morning MVFR/IFR ceilings expected over northeast
Wyoming and northwest South Dakota. This area will expand east
and south this afternoon and evening. Showers with isolated
thunderstorms possible over far south central South Dakota late
this afternoon and evening. As the precipitation shifts southward
tonight, rain will change over to snow for the Black Hills with
local IFR visibility.




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