Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 202030

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
230 PM MDT Tue Mar 20 2018

.DISCUSSION...(This Evening Through Tuesday)
Issued at 229 PM MDT Tue Mar 20 2018

Compact vort max pushing through the Dakotas, supporting some
diurnal rain/snow showers, esp SE of the BH. Convection will begin
to wane late this afternoon, with showers trending SE into NE. An
ISOLD TS will still be possible, mainly around the Pine Ridge
area this afternoon. Some fog will be possible later tonight,
mainly over the eastern FA. WAA will prevail Wed through Fri as
trough re-loading commences over the western CONUS. Dry wx
expected Wed, with a WAA convergence zone possibly supporting a
few rain or snow showers across the NE half Thur night into
Friday. Deep western CONUS trough will eventually shift east this
weekend, with precip chances increasing across the Northern
Plains. This will support a period of rain or snow this weekend
into early next week. Chances for precip in this period will
likely waver over the coming days as models settle on a solution.

Temperatures will warm over the SW half the next few days where
the snow pack is either thin or missing. This will support spring
like temps through the work week there (cooler over the NE half)
with cooling temps into this weekend all places as the upper
trough shifts east.


.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1108 AM MDT Tue Mar 20 2018

VFR conditions are generally expected at KGCC/KRAP through the
TAF period. Brief SN/RA showers cannot be ruled out this
afternoon at KRAP and over the surrounding SD plains, which could
temporarily lower cigs/vsbys to MVFR/IFR. An isolated lightning
threat may also develop in deeper showers.

Tonight, patchy BR/FG may again develop, particularly in low-lying
areas of the SD plains with relatively fresh snowpack. If so,
MVFR/IFR and localized LIFR conditions will be possible.




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