283
FXUS65 KRIW 040917
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
217 AM MST Tue Nov 4 2025

.KEY MESSAGES...

- Increased winds off the east slopes of the Absaroka, Wind
  River and Bighorn Mountains continue overnight with isolated
  gusts of 50 to 60 mph expected for favored locations.

- Precipitation chances increase across northwest WY this
  morning. Impacts will be limited with only light snowfall
  accumulations above 8000ft in the northwest WY mountains.

- Temperatures remain well above normal through the rest of this
  week, with warmest temperatures (10 to 15 degrees above
  normal) on Tuesday and Wednesday.

- Several more weak weather systems will bring chances (30 to
  50%) for rain and mountain snow showers to western WY
  Wednesday night into Thursday and again on Friday into
  Saturday.

&&

.DISCUSSION...
Issued at 216 AM MST Tue Nov 4 2025

A shortwave will continue to push through the region today, with the
main impact being wind. Favored locations will generally be the
Cody/Clark area including Chief Joseph highway. 700mb flow of 50 to
60kts is progged with the passage of the trough axis and winds
should peak around late morning, before slowly decreasing through
the afternoon. Mountain waves are possible as this system moves
through. Westerly winds gusting 40 to 50 mph are expected for the
aforementioned locations, with occasional gusts to 60 to 65 mph
possible (20% chance). As the trough axis slides from west to east
through the day, increasing westerly winds are expected across much
of the region. Gusts around 30 to 35 mph will be expected for
westerly flow favored locations notably from South Pass to Casper
and across Sweetwater County. Portions of Bighorn County also are
expected see some gusty winds through the afternoon, as well as
around Dubois.

With this shortwave, there will be a bit of precipitation as well.
Precipitation chances generally increase around sunrise this
morning, with 20 to 30% chances persisting across the northwest WY
mountains and YNP through much of the afternoon. Given dominant
ridging, temperatures remain warmer than normal and thus snow levels
will remain at or above 8000 ft, well above valley level. Snowfall
accumulations above 8000 ft will be limited (2 to 4 inches at the
highest peaks). Valleys could see some occasional rain showers
through the day with this system as well, but any amounts will be
limited, as the shortwave becomes quickly cutoff from any Pacific
moisture flux. Precip chances decrease through the evening and any
lingering light showers will end by sunrise Wednesday.

Ridging does continue to dominate the pattern through the rest of
the week. That means the above normal temperatures continue. Today
and Wednesday will see temps 10 to 15 degrees above normal, despite
the shortwave moving through. Downsloping winds will lead to a well-
mixed boundary layer today, and thus temperatures will quickly climb
into the 60s for many locations east of the Divide today. Though we
may flirt with a few daily temperature records, temperatures at this
time look to stay below record warm values. The gusty westerly winds
and unseasonably warm temps will lead to elevated fire weather
conditions across much of the area, especially across southwest WY
and the Wind Corridor where RHs will flirt with critical values.

A broad low will start to push down into the Pacific NW Wednesday
night which will filter more consistent moisture in zonal flow into
western WY. This will come in two waves, the first being Wednesday
night into Thursday and the other Friday into Saturday. Amounts for
both events look marginal at this time, with the second wave looking
to be more potent than the first. Impacts look to remain focused
across the western mountains, with snow levels remaining above valley
levels through much of the event.

Ridging looks to rebuild by the second half of the weekend and
persist into the early next week. Temperatures will moderate back to
near seasonal norms Thursday through Saturday with the Pacific
moisture influence and more widespread cloud cover. But with the
rebuilding ridge, expect temperatures to rebound to much above
normal Sunday and especially by Monday.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1000 PM MST Mon Nov 3 2025

Turbulent winds will be in place over the Absarokas and
Yellowstone NP to start the forecast, increasing along the east
slopes of the Wind River and Bighorn Mountains. LLWS will
result over these areas, with winds ranging between 35 to 50 kt.
KCOD will be the only terminal to be impacted through 18Z. Sfc
winds, with gusts of 20 to 40 kt, will become widespread across
the forecast area by 18Z. The higher winds of 40 to 50 kt will
continue over the east slopes of the Absaroka, Bighorn and Wind
River Mountains. These winds will subside after 00Z, lingering
over the mountains through the rest of the TAF period.

Lee enhanced clouds will be in place over the Bighorn Basin and
Johnson County to start the forecast and remain in place through
18Z. Clouds will increase over Yellowstone and Teton County
after 12Z. Conditions will remain VFR, but ceilings will drop to
around 5000ft over the Jackson Valley by 18Z. These conditions
will continue into the evening, before beginning to lift by 06Z
Wednesday.

Mountain obscurations will increase over Yellowstone, the
Tetons/Gros Ventres and the west slopes of the Absaroka and Wind
River Mountains after 15Z. These conditions will remain in place
for most of these areas through the rest of the forecast.

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...
None.

&&

$$

DISCUSSION...Hensley
AVIATION...LaVoie