932
FXUS65 KRIW 090926
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
226 AM MST Tue Dec 9 2025

.KEY MESSAGES...

- Moderate snowfall will continue across the NW higher
  elevations today and through Thursday. Total snow accumulation
  through Thursday will reach 2 to 3 feet. Warmer valley
  temperatures will inhibit most snowfall accumulations.

- Very windy across much of the state today, with High Wind
  Warnings in effect for much of southern and central Wyoming.

- Temperatures remain 10 to 20 degrees above normal

&&

.DISCUSSION...
Issued at 145 AM MST Tue Dec 9 2025

The next passing shortwave energy is beginning to impact the NW
higher elevations this morning, and the overall flow the next
several days continues to be favorable for continued snow
accumulation. Between orographic lifting and the passing wave,
accumulations of 2 to 3 feet are becoming more likely for the
Tetons and Absarokas, with 6 to 12 inches for remaining higher
mountain ranges and the greater YNP region. Current variety of
winter warnings and advisories are well positioned, so no
adjustments needed at this time. In a usual winter, temperatures
would be cold enough to help get some of this precip into the
lower valleys, but not this year. Temperatures today will be in
the 40s for the western valleys, and in the low 50s for the
lower elevations east of the Divide, so snowfall will be locked
into the mountains for the remainder of the week.

The core of the llvl jet streak will be passing by just to the
north today, and with temperatures in the 50s, a large chunk of
this wind energy will mix to the sfc during the afternoon. With
H7 winds at 70kts as they pass by, peak sfc wind gusts of 50 to
60 mph are likely for southern WY stretching NE into the Casper
vicinity. The only question is winds across northern Johnson
County late this afternoon as the cold front barrels through.
While winds sfc and aloft are aligned, models are not really
bringing winds up until the system gets a little farther east.
Will monitor this if High Wind Warnings are needed there.

Beyond this, the H5 ridge along the Rockies doesn`t move much
through the weekend, deflecting weather systems to the north and
east, and keeping the unusually warm temperatures in place.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 930 PM MST Mon Dec 8 2025

VFR conditions to start the period with JAC having low ceilings
but VFR. Snow showers for JAC but light in nature overnight with
all other TAF sites dry. A rain/snow mix likely at JAC after 15Z
due to warmer temperatures after sunrise becoming straight snow
after 01Z with nighttime cooling. Minimal chances at COD/WRL/CPR
after 19Z carrying only VCSH through 01Z. Otherwise, windy
conditions throughout the period remaining elevated overnight.
Strongest winds at COD/JAC/RIW up to 30kts with RKS up to 45kts
after 17Z remaining elevated overnight into Wednesday as well up
to 30-35kts. Other locations will be breezy but less winds up to
18-25kts. Mid level ceilings throughout for all locations
remaining VFR except JAC down to MVFR around 1-1.5kft in the
late afternoon/early evening timeframe.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on smoke, icing, and turbulence
forecasts.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 5 PM MST Wednesday for WYZ001-002.

Winter Weather Advisory from 5 AM early this morning to 5 PM
MST Wednesday for WYZ008-014-015-024.

Winter Storm Warning from 5 AM early this morning to 5 PM MST
Wednesday for WYZ012.

High Wind Warning until 2 PM MST this afternoon for WYZ016.

High Wind Warning until 5 AM MST Thursday for WYZ019-020-022-
027>030.

&&

$$

DISCUSSION...Straub
AVIATION...Lowe