133
FXUS65 KRIW 020504
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1004 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 /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 950 PM MST Mon Dec 1 2025

West of the Continental Divide...KJAC/KRKS/KPNA/KBPI Terminals

Snow already starting to pick up at KJAC this evening, and is
still expected to pass through in two waves during the next 24
hours. The first is now through around 09Z with TEMPO MVFR vis
and cigs. There will be a break the rest of the night into
Tuesday morning, with snow confined to nearby higher terrain.
The next wave still expected around 16Z, with a better
probability of lower cigs and vis reaching IFR ranges.
Likelihood of precip at KBPI/KPNA/KRKS remains low with this
system, with main impacts being lower cigs after 00Z/03. Gusty
winds at KRKS will continue well into the day Tuesday, with
frequent gusts near 35kts.

East of the Continental Divide...KCPR/KCOD/KRIW/KLND/KWRL Terminals

Cloud cover will remain confined to mid to higher level decks
through tomorrow morning. The second wave will come through east
of the divide during the day Tuesday, with gradually lowering
cigs. Winds will shift from the north during the afternoon as
the cold front starts to push through. The main push will be
after 00Z/03, and will quickly bring lower cigs and -sn to
these sites. Have added a -sn/low vis line late in TAFs for
this, but timing is still not set in stone yet. Once the front
does move through, expect cigs to fall quickly to IFR/LIFR,
with -sn through the rest of the night.

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 until 11 PM MST Tuesday for WYZ012.

&&

$$

UPDATE...Dziewaltowski
DISCUSSION...LaVoie
AVIATION...Straub