Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 210529

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1029 PM MST Tue Feb 20 2018

.DISCUSSION...(This Evening Through Tuesday)
Issued at 226 PM MST Tue Feb 20 2018

Upper trough is centered across the western half of the CONUS with
surface high pressure crossing the Dakotas. Skies have become
mostly sunny aside from some light smoke over some portions of the
CWA. Clear skies will continue tonight with temps dropping to well
below freezing once again. Southerly flow will set up overnight as
high pressure slides east of the region. Winds combined with cold
temps will result in wind chills of 20 below to 30 below zero.
Wind Chill Advisory has been issued for all areas except the SD
Black Hills where temps will be warmer, but still below zero.
Upper trough will persist over the western CONUS and intensify
Thursday as a strong shortwave drops down the Pacific Coast. A
series of shortwaves will eject out across the central Plains
bringing snow to Nebraska and eastern South Dakota. At this time
it appears the snow will graze south central South Dakota Thursday
afternoon/evening. However, snowfall totals will be limited to an
inch or so. Gradually warmer temps are expected each day through
the second half of the week, reaching the mid 30s in some
locations by Saturday or Sunday. Dry weather is expected across
the CWA as the main active flow remains to the south/east.


.AVIATION...(For the 06Z TAFS Through 06Z Wednesday Night)
Issued At 1028 PM MST Tue Feb 20 2018

VFR conditions are expected through Thursday afternoon across
most of the area, including at TAF sites. Patchy low-level smoke
remains possible near the Black Hills overnight due to prescribed
burns from earlier Wednesday.

Near the end of the TAF period, BR/FG will likely develop across
portions of the area due to continued south and southeasterly flow
over widespread snowpack. Confidence is currently low in associated
impacts at TAF sites, but we will need to monitor the potential
for reduced cigs/vsbys after 00z, particularly at KRAP.


SD...Wind Chill Advisory until 9 AM MST /10 AM CST/ Wednesday for

WY...Wind Chill Advisory until 9 AM MST Wednesday for WYZ054>058-071.



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