315
FXUS65 KRIW 041853
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1153 AM MST Tue Nov 4 2025

.KEY MESSAGES...

- Strong wind off the east slopes of the Absaroka, Wind River
  and Bighorn Mountains as well as the Wind Corridor continues
  this afternoon with isolated gusts of 50 to 60 mph expected
  for favored locations.

- Precipitation remains ongoing across northwestern Wyoming this
  afternoon. 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) Today and Wednesday.

- Fire weather conditions will be elevated this week, especially
  today 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.

&&

.UPDATE...
Issued at 1150 AM MST Tue Nov 4 2025

Rain and snow continues across northwest Wyoming this afternoon as
the shortwave pushes through the area. The precipitation type will
remain all rain below 8000 ft, with all snow above 8500 ft.
Precipitation comes to and end by sunrise Wednesday as the
weather system exits the area quickly. As expected it is breezy
to windy for most of the area already and this will continue
through the afternoon until sunset. Mountain lee high clouds are
limiting the warmup this morning in the Wind River Basin and
Bighorn Basin, but probably not enough to prevent mix- out from
occurring at some point this afternoon. With mix-out occurring
temperatures are rising well above normal into the low to mid
60s east of the Continental Divide. Due to the above normal
temperatures, dry conditions, and strong wind fire weather
conditions will remain elevated for much of the area through
this afternoon. Weather conditions will be similar tomorrow, so
fire weather concerns will continue. The overall weather pattern
remains consistent for the rest of this week, with zonal flow
and embedded shortwaves leading to persistent chances of
rain/snow across western Wyoming. Model guidance is fairly
certain the pattern will become more amplified this weekend into
next week.

&&

.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 /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1023 AM MST Tue Nov 4 2025

VFR conditions will prevail across nearly all terminals through much
of the TAF period. One exception to this will be KJAC where a
nearing disturbance is expected to bring in precipitation chances by
the start of the period. Ceilings will also begin to lower with MVFR
conditions possible throughout the afternoon and evening.
Precipitation chances are low, so only VCSH have been added to
KJAC`s TAF. Conditions are expected to begin to improve at KJAC by
the late evening Tuesday with improving ceilings through the
overnight. Other terminals will see increasing cloud cover with SCT-
BKN ceilings of 100-150 Tuesday evening into Wednesday morning.

The other concern is gusty winds expected across some terminals
through the TAF period. The strongest winds look to be at KCPR and
KCOD where winds of 20 to 30 knots are expected this afternoon and
evening with periodic gusts of 35 to 45 knots possible. Other
terminals will see increasing winds as well with speeds around 10 to
20 knots with gusts of 25 to 30 knots. Winds gradually dissipate
this evening into the early morning hours on Wednesday. Breezy winds
return by the end of the TAF period across mostly all terminals.
Mountain obscuration will be likely through much of the TAF period
mainly across western ranges especially nearby KJAC. Obscuration may
begin to improve by the morning hours Wednesday into the end of
the TAF period.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...Rowe
DISCUSSION...Hensley
AVIATION...Dziewaltowski