148
FXUS63 KUNR 050940
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
240 AM MST Fri Dec 5 2025

.KEY MESSAGES...

- Light snow returns tonight into Friday, then another chance on
  Saturday and Sunday.

- Warmer and breezy conditions early next week.

- Unsettled weather may return for the middle of next week.

&&

.DISCUSSION...(Today Through Thursday)
Issued at 238 AM MST Fri Dec 5 2025

Upper air analysis shows northwest flow continuing from the Pac NW
all the way to the Upper Midwest, with a series of embedded waves.
The next disturbance to affect the area is crossing central/eastern
MT ATTM. Surface analysis shows a broad trough extending from the
Dakotas into central Canada, supporting W/NW winds of 10-20kt...and
gusts up to 30kt over the NW SD plains. KUDX radar shows light snow
moving into portions of NE WY and the northern Black Hills, which is
expected to bring an inch or two of snow by 12-14z this morning. The
wave will cross the area mid-morning...behind it weak mid-level
subsidence to the CWA, ending the best chance for accumulating
snowfall. However, steep low level lapse rates will persist through
the day, allowing for continued low clouds and flurries/light snow.
Any accumulations that does occur for the remainder of the day will
be less than an inch. Surface high pressure will move into the
Dakotas tonight, bringing a brief dry period before the next round
of unsettled weather moves in on Saturday. A surface low will
develop ahead of the next wave, along a stalled weak baroclinic
zone. Isentropic forcing will increase ahead of the low over south
central SD, then quickly move southeast of the CWA. Northerly flow
behind the low will reinforce the colder air and will be the focus
for precip Saturday and Saturday night. Snow is expected across much
of western SD and the northern Black Hills...with southwest SD as
the only exception. The highest snow amounts will be over NW SD (1-
3") and the northern Black Hills (1-4"). Lingering snow will be
possible on Sunday, especially as models suggest another wave
pushing through. Snow amounts will be minimal. Low amplitude dirty
ridge then builds over the western CONUS, supporting strong warm air
advection. In addition to dry weather, temps should reach into the
40s/low 50s on Monday...then about 5 degrees warmer on Tuesday,
along with breezy conditions. Unsettled weather could return toward
the middle of next week, but there remains much uncertainty at this
time.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Friday Night)
Issued At 946 PM MST Thu Dec 4 2025

MVFR/IFR conditions and areas of -SN will develop across
northeastern WY into northwestern SD and the northern Black Hills
through early this morning. Conditions should improve through the
day, though MVFR conditions may linger across northwestern SD
through late in the TAF period. Northwest winds will also pick up
through the overnight hours into the morning especially across
northwestern SD where gusts of up to 37 kt are possible.

&&

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

$$

DISCUSSION/KEY MESSAGES...13
AVIATION...Wong