181 
FXUS63 KUNR 012329
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
529 PM MDT Tue Oct 1 2019

.DISCUSSION...(This Evening Through Tuesday)
Issued at 157 PM MDT Tue Oct 1 2019

Western CONUS upper trough is slowly pushing east today with 
light rain and snow showers across the area, even some freezing 
rain at times in the higher elevations. Fairly unusual setup for 
the time of year, with satellite and bufr progs confirming a lack 
of ice in the mid and upper levels given warm ll profiles, 
resulting in the the production of freezing rain when combined 
with unseasonably cool 2m temps. This setup will remain relatively
unchanged through the next 24 hours with the best FGEN forcing 
(deeper) remaining across far NW portions of the FA (mainly along 
and north of a line from KGCC to KBIS) where ice crystal 
production will favor snow from the next jet streak/impulse 
advecting through the area. Further south, a mix of rain, freezing
rain, and sleet will be possible. Although profiles support 
freezing rain (mainly in the Black Hills and portions of NE WY), 
any ice accretion will be highly limited given low expected QPF, 
warm surfaces, and temps right around freezing. Snow accums are 
expected across far northern Campbell county into Norther Harding 
and Perkins counties Wed morning where the best forcing for deep 
ascent will be. Current forecast snow amounts will are in the 
0.5-1.5 inch range, with the highest totals expected on ridge 
tops/buttes/hills and on grassy sfc’s. Another very cold day 
expected (for the season) with highs in the upper 30s and lower 
40s once again. Precip will shift NE during the day and wane with 
drier air expected to shift NE into the region from the SW late in
the day. This will begin to scour clouds out from SW-NE through 
the night with most places expected to clear and radiationally 
cool overnight, supporting widespread frost and a freeze most 
places. The exception will be south central SD and possibly far NW
SD. Clouds may linger with sustained mixing through the night 
across NW SD, holding temps up and possibly limiting frost. WAA 
and dry weather expected Thur through Friday. Another shortwave 
will push through the region Friday night into Sat, supporting a 
chance of showers most places and another brief cool down through 
the weekend. Forecast models are starting to agree on deep layer 
ridging next week, which would support a decent period of warm and
dry weather, with highs in the 70s and possibly 80s.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Wednesday Evening)
Issued At 522 PM MDT Tue Oct 1 2019

MVFR CIGS will persist over much of central South Dakota, with 
IFR conditions persisting over far western SD and northeastern 
Wyoming. Occasional rain and some light snow are expected over 
northeastern Wyoming and the Black Hills, with some light freezing
precipitation mixed in. Precipitation will begin to move out of 
the area toward the end of TAF period. 

&&

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

$$

DISCUSSION...JC
AVIATION...15