546
FXUS65 KRIW 012254
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
354 PM MST Mon Dec 1 2025

.KEY MESSAGES...

- Dry conditions with more seasonable temperatures across the
  state today.

- A nearing disturbance will bring increased chances for
  precipitation starting this evening over northwestern/western.

- Strong gusty winds will accompany the first push of
  precipitation leading to blowing snow and hazardous conditions
  over some western mountain passes especially Tuesday morning.

- Precipitation chances spread east of the Divide Tuesday
  evening through Wednesday morning. A light accumulation of
  snow may be possible in some locations by Wednesday morning.

&&

.UPDATE...
Issued at 1208 PM MST Mon Dec 1 2025

The short term forecast remains mostly on track with little change
compared to the overnight. Temperatures today will be warmer than
the past few days across much of the state. Highs are forecast to
get into the upper 20s to low 30s. Low clouds are expected to linger
across western valleys through much of the day this includes
locations like Star Valley along with parts of Jackson Hole.
Forecasted winds look to be mostly unchanged with breezy conditions
developing through the afternoon today in portions of the state.
Stronger gusty winds will make their way into the area late this
evening into the early morning hours Tuesday. The timing and impacts
from the next disturbance thats expected to move through the region
tonight through Wednesday remain mostly unchanged. Snow showers look
to move into northwestern WY this evening gradually spreading east
and south through the day Tuesday into Wednesday. The best chances
for snow showers east of the Divide will arrive late Tuesday through
Wednesday morning. Models keep impacts minimal east of the Divide
with possibly a coating to an inch or two by Wednesday morning. A
Winter Weather Advisory goes into effect late this evening for the
Tetons and Gros Ventre Ranges. These mountains could see anywhere
from 3 to 6 inches with higher amounts nearing 6 to 12 inches
likely for the Tetons. Winds look to be gusty at times in
conjunction with the snowfall, which may lead to some hazardous
conditions over mountain passes such as Togwotee and Teton Pass.
Otherwise the remainder of the week looks on track with little
change in the forecast.

&&

.DISCUSSION...
Issued at 122 AM MST Mon Dec 1 2025

Snow ended across the area earlier Sunday evening. Apart from a few
high clouds, skies will be clear this morning for most of the area.
Some low clouds/fog could push into the Star Valley in the next few
hours, as well as areas along Hwy 28 near Farson. Conditions will
remain dry today, with temperatures about 5 to 10 degrees warmer.
Some locations will be 15 to 20 degrees warmer from Sunday, due to
highs in the teens yesterday. Winds will be a bit breezy today, with
gusts of 25 to 30 mph occurring across southern portions and Natrona
County. Areas near Dubois and Cody will also be breezy, with locally
higher gusts around 35 mph.

Another storm system will quickly make its to the CWA from the north
this evening, with snow developing over northwestern portions by 04Z
Tuesday and spreading southward through the rest of the night
tonight. Winds will increase over the east slopes of the Absaroka
and Wind River Mountains irt this latest (third) storm system. West
to northwest winds, with gusts of 35 to 45 mph, will develop by 06Z
and continue through much of the day Tuesday. These conditions will
occur at Dubois, Cody and Clark as well. These winds will then
spread across southern portions of Fremont and Natrona counties by
12Z. Gusts of 50 to 55 mph will be possible along Hwy 258 on the
south side of Casper. Gusts of 25 to 30 mph will then be common
after 18Z across areas west of the Divide and portions of the Wind
River Basin. Isolated snow showers will also occur across areas east
of the Divide through the afternoon and become more widespread in
the evening, as the associated cold front makes its way southward.
This system will be a bit slower than the previous two, with light
snow continuing through Wednesday morning. Snowfall amounts of 1 to
2 inches is expected over central portions and the western valleys,
with 3 to 6 inches in the mountains.

Snow will end across the area through the rest of the morning
Wednesday, as high pressure builds into the area from the north
through the afternoon. Conditions will remain dry Wednesday night
and Thursday, with a chance for snow over northwestern portions due
to upslope flow from another incoming system on Friday. Impacts from
this storm will be widespread once again, however it will track
further north so snowfall amounts look to stay on the light side
again. Periods of snow look possible Friday and Saturday across
western portions, due to the semi-consistent upslope flow. Exact
details will become clearer in the next few days as we progress
through the week.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 351 PM MST Mon Dec 1 2025

A shortwave will move through this evening, bringing increased cloud
cover and gusty winds to much of the area. With this, light snow
will also occur at KJAC. For the most part, snow showers will remain
along the surrounding terrain, but hi-res models do continue to
indicate a push of snow through the valley from 05Z to 09Z tonight
(70% chance), which could result in brief IFR or lower conditions at
KJAC (30% chance), most likely from 06Z to 08Z. MVFR or near MVFR
conditions will persist at KJAC after that through the rest of the
period with increasing chances after 16Z Tuesday morning.

As mentioned, gusty winds will accompany today`s shortwave,
particularly at KCPR and KRKS. KCPR and KRKS will see winds
increase slightly this evening with gusts around 25 to 35kts
continuing through Tuesday afternoon. KCOD will also see
increasing winds through the evening with gusts 20 to 30kts
through much of the night. There could be some LLWS/mountain
wave potential at KCOD during the evening and overnight (20 to
30% chance), but confidence is not high enough to include in the
TAF at this time.

A secondary shortwave will begin to push into the region late in the
period, which brings lowered cigs for KJAC, as well as a cold front.
The cold front looks to begin to push into northern terminals
(KCOD/KWRL) right at the end of the period, with impacts and gusty
north winds generally holding off until after 00Z Tuesday evening.

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 Weather Advisory from 11 PM this evening to 11 PM MST
Tuesday for WYZ012.

&&

$$

UPDATE...Dziewaltowski
DISCUSSION...LaVoie
AVIATION...Hensley