Expires:No;;141727
FXUS63 KUNR 040522
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1022 PM MST Tue Dec 3 2024

.KEY MESSAGES...

-Highly variable temperatures through the period as a frontal 
 boundary wavers over the region

-Mainly dry in the period with chances for light snow and 
 flurries with any passing system, best chances over northwest SD

&&

.DISCUSSION...(This Evening Through Tuesday)
Issued at 125 PM MST Tue Dec 3 2024

Frontal boundary will continue to waver over the region through 
the period as a series of impulses ride SE along the frontside of 
the mean western NOAM ridge. Warm Pac downslope flow has spread 
across the region today, with temps in the 50s and 60s most 
places. Strong impulse is diving SE across eastern MT and will 
bring a cold front in the region tonight. Some light snow/flurries
will be possible behind the front, mainly over NW SD, with 
chances shifting west during the day Wednesday. Highs will occur 
tomorrow morning most areas with temps falling during the day. 
Much colder temps Thur with the SD plains once gain stuck under 
the inversion as warm air starts to push back east aloft. This 
will allow milder temps in NE WY and the BH once again. Did knock 
temps down on the SD Plains Thur given expected inversion. Temps 
will quickly moderate with another round of mild westerly flow 
through the end of the week as the western NOAM ridge shifts east,
warmest Saturday. Models continue to advertise a stronger cold 
front Sun-Monday as the northeast Pac upper trough tops the ridge 
and drags down another chunk of arctic air. Some light snow is 
also likely with this system with light accums possible wherever 
FGEN sets up. Deeper trough will then settle into the western 
CONUS, supporting a little longer duration of cooler temps into 
mid week, with some warming toward the end of next week as semi- 
zonal flow looks to become established.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Wednesday Night)
Issued At 1018 PM MST Tue Dec 3 2024

A back door cold front will slip southwest across the area
overnight into Wednesday. Along the front, a band of MVFR CIGS
will develop, mainly over northwestern SD into far northeastern 
WY, including the higher Black Hills where local IFR CIGS are
possible. The probability the lower clouds will affect the 
KRAP/KGCC terminals is low, so will leave out for now with CIGS
around 4kft AGL. Gusty north/northwest winds (~40kts) will 
develop behind the front, especially for northwest into south-
central SD.

&&

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

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...Helgeson