Area Forecast Discussion
Issued by NWS Rapid City, SD

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096
FXUS63 KUNR 231631
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1031 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 18Z TAFS Through 18Z Friday)
Issued At 1027 AM MDT Thu Mar 23 2017

MVFR/IFR cigs due to -shra expected to continue spreading from
nern WY through far wrn SD this afternoon, then across cntrl SD
this evening. Isolated thunderstorms possible over the srn Blkhls
and across srn SD late this afternoon and evening. As the
precipitation shifts southward tonight, rain will change over to
snow for the Blkhls with local IFR visibility. Pcpn will end from
west to east late tonight, although it will continue across scntrl
SD through midday Friday.

&&

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

$$

SHORT TERM...7
LONG TERM...7
AVIATION...Johnson



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