743
FXUS63 KUNR 221155
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
455 AM MST Fri Nov 22 2024

.KEY MESSAGES...

- Weak cold front tonight with some fog potential on the plains
  north and east of the Black Hills.

- Cold front Sunday with gusty northwest winds and small
  chance(<35%) of light snow/flurries

- Below average temperatures through Thanksgiving with slight
  chance(<20%) of snow.

&&

.DISCUSSION...(Today Through Thursday)
Issued at 126 AM MST Fri Nov 22 2024

Current surface map places high pressure across the eastern
Dakotas with trough/warm front across western South Dakota.
Abundant mid/high clouds across the Northern Plains. Quite day
today with partly sunny skies. Highs in the 40s to mid
50s...warmest across southwestern South Dakota. Weak cold front
slips into western South Dakota tonight, with shallow/moist
upslope flow late. Forecast soundings support low stratus/fog on
the plains north and east of the Black Hills. HREF probability of
visibility <3 miles is 50-75%; highest along the I-90 corridor.
Return flow increases on Saturday with broad area of pressure
falls across the Northern Plains. Temperatures a bit tricky on
Saturday with cooler southeasterly flow reinforcing shallow
boundary layer inversion. This will result in wide range of highs
Saturday; from the lower 30s in northwestern South Dakota to the
mid 50s in northeastern Wyoming and far southwestern South Dakota.

Shortwave tracks across Montana/North Dakota Saturday night, with
cold front moving through the area late Saturday night into Sunday
morning. 3-4mb/3hr pressure rises and robust cold advection will
bring a period of gusty northwest winds behind the front. There is
a chance of light snow/flurries (<35%) on Sunday, mainly over the
Black Hills and northeastern Wyoming. Little to no accumulation
expected.

Upper flow transitions from zonal to northwesterly for the
upcoming holiday week, setting the stage for below average
temperatures. A few weak impulses move through the area bringing
small chances (<20%) of light snow.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 454 AM MST Fri Nov 22 2024

VFR conditions will persist through Friday. Patchy fog will
develop across the western South Dakota plains after 09-11z
Saturday morning, although probability in impacts at KRAP is low
at this time.

&&

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

$$

DISCUSSION/KEY MESSAGES...7
AVIATION...SE