836
FXUS65 KRIW 072031
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
131 PM MST Fri Nov 7 2025

.KEY MESSAGES...

- Western mountain snow and valley rain chances through this
  evening (50-70%) with main impacts for Togwotee and Teton
  Passes.

- Gusty winds decrease for most areas this evening. Another weak
  front moves across eastern WY on Saturday, bringing gusty
  northwest winds across Johnson and Natrona Counties. Some
  crosswind gusts near 50 mph are possible along I-90.

- Warming and dry trend Sunday and into much of next week.

&&

.UPDATE...
Issued at 1247 PM MST Fri Nov 7 2025

The latest trough continues to sweep quickly across Montana, and
is progressing as scheduled. Northwest flow around the edge of
the trough continues to produce some snowfall for the NW
Mountains and should be moving across the Bighorn Range late
this afternoon. Snowfall has been slow to accumulate, if at
all, so impacts will remain limited to the main mountain passes.
The cold front is just now moving into the northern fringes of
the state, and will move deflect across areas east of the divide
overnight. Temperatures tomorrow will be about 10 degrees
colder than today, and will be accompanied by a brisk northwest
wind. Models have been struggling to pick up on the surge of
north winds tomorrow morning, so have nudged winds upwards,
especially along the more prone NW wind corridor across Johnson
County.

&&

.DISCUSSION...
Issued at 1230 AM MST Fri Nov 7 2025

WV imagery continues to reflect the westerly moisture rich flow
from the Pacific northwest becoming more northwesterly over the
state and into the Great Plains. IR shows the next shortwave
pushing across Idaho as of midnight, expecting to push into
western portions of Wyoming later this Friday morning. Radar
shows nothing of note currently and expected to remain dry until
after sunset for far west portions near the state line before
expanding east to the Divide by late morning.

A 90-100kt jet max aids in supporting the aforementioned
shortwave propagating to the expanding diffluence aloft as the
day progresses Friday. The surface front will makes its way
through the CWA during the afternoon hours expanding the
precipitation chances east of the Divide after sunset and
overnight into Saturday morning. Best chances here will be the
northern Bighorn Basin and across the Bighorns into
Johnson/Natrona Counties (40-60%). Light mountain snow for the
Bighorns to a bit of lower elevation rain as the precipitation
types with PWAT values less than a quarter inch. West of the
Divide will be the most impacted expected the higher elevation
snow and lower valley rain. Highest snow accumulations for the
Tetons to northern portions of the Winds up to 4 to 8 inches as
the most likely range. Teton Pass will see up to 3 to 4 inches
(70-80%) and Togwotee Pass up to 4 to 5 inches (80-90%). These
will be the areas of any concern for impacts outside of the
higher terrain travel wise.

Otherwise, expect the gradient to strengthen ahead of FROPA in
the afternoon hours. Wind gust up to 20 to 30 mph west of the
Divide and up to 30 to 40 mph to the east, with higher gusts
likely (80-90%) for the wind prone areas from Sweetwater to
Natrona County, as well as funneling through the upper Wind
River Basin. Winds will shift from more southwesterly to west-
northwesterly after FROPA diminishing with time towards sunset
as daytime heating dissipates to radiational cooling in the
evening and overnight. Precipitation lingers overnight into
early Saturday morning likely ending before sunrise.

The next subtle feature will be with another weak shortwave that
will push to the northeast affecting northern portions of
Johnson County Saturday afternoon. A weak frontal boundary will
tighten the gradient for these area off the Bighorns resulting
in wind gusts up to 40 to 50 mph, with isolated gusts over 50
mph possible (50-60%). High wind criteria being reached does not
look likely IAW HREF data, and opted to not do any wind
highlights at this time. Beyond that, high pressure and ridging
builds in from the west and southwest with a 595 dm high
centered near the Four Corner Region to expand through the upper
Rockies. This will give way to a warming and dry trend from
Sunday onward into much of next week. The next storm system
looks to push in by Thursday with low confidence on timing with
longer term models not in agreement on its speed. Strength wise,
however, there is better alignment on a bigger impact storm
possible for much of the CWA by week`s end and into the
following weekend. Stay tuned for updated forecasts in the
coming days.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1029 AM MST Fri Nov 7 2025

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

VRF/MVFR conditions will develop across nearly all terminals for the
start of the TAF period. Conditions will decrease through the
afternoon with most terminals seeing near to MVFR conditions. This
is the result of a nearing disturbance that will bring increased
winds, lowering ceilings and precipitation chances. KJAC looks to
see the greatest impacts with spotty showers around the terminal to
start the period. Ceilings will continue to lower as the bulk of the
precipitation enters the area this afternoon/evening. Prevailing
precipitation groups begin around 21Z Friday persisting through 01Z
Saturday with a few isolated showers nearby through 04Z.
Temperatures will be near freezing so there may be some mixing of
rain/snow but a transition over to snow will be likely later in the
evening. A brief period of IFR condition cannot be ruled out at
times. KPNA, KBPI, and KRKS have much lower chances for seeing
precipitation and due to this no precipitation groups are in
their TAFS. However, a brief isolated rain/snow shower cannot be
ruled out during the afternoon and evening today. VFR
conditions will gradually return to all terminals through the
overnight into the early morning hours on Saturday. The other
concern will be gusty winds at all terminals this
afternoon/evening. Winds of 15 to 20 knots will be possible
shortly after the start of the period with gusts of 25 to 30
knots at times. KRKS may see slightly stronger gusts of 35 to 40
knots. Winds weaken after sunset becoming light through the
remainder of the period. Mountain obscuration will be widespread
to start the TAF period with obscuration likely not improving
until the morning hours on Saturday.

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

VFR conditions will prevail for much of the period across nearly all
terminals. The only exception to this will be KCOD, KWRL, and KCPR
where a nearing disturbance will bring lowered ceilings and
precipitation chances this afternoon/evening. Rain/snow showers look
to start developing nearby KCOD and KWRL around 22Z Friday with KCPR
seeing showers around 00Z Saturday. MVFR to possibly IFR conditions
will be possible at these terminals around this time. Conditions
should begin to improve late Friday evening into the early morning
hours of Saturday. Winds will increase across all terminals this
afternoon/evening with speeds of 15 to 25 knots. Gusts of 20 to 30
knots will be possible at times with KCPR possibly seeing stronger
gusts of 35 to 40 knots. Winds gradually weaken after sunset
becoming light through the rest of the TAF period. Mountains will
likely become obscured shortly after the start of the period with
improvement not expected to occur until the morning hours on
Saturday.

&&

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

&&

$$

UPDATE...Straub
DISCUSSION...Lowe
AVIATION...Dziewaltowski