438
FXUS65 KRIW 021848
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1148 AM MST Mon Nov 2 2026

.KEY MESSAGES...

- Rain and mountain snow decreases through the afternoon, ending
  by midnight for most locations. Gusty north winds persist
  around Johnson County into tonight, becoming calm by sunrise.

- Recent moisture and a clearing sky favors valley and basin fog Tuesday
  morning, which could impact the morning commute.

- Drier conditions for the rest of the week, with seasonal to
  slightly below average temperatures.

&&

.UPDATE...
Issued at 1147 AM MST Mon Nov 2 2026

No notable changes with this update. As the system tracks eastwards,
rain and snow decreases, along with winds, through the afternoon.
Winds remain gusty around Johnson County overnight, but should fall
under less than 10 mph between midnight and sunrise. Fog will be the
forecast concern for Tuesday morning. Recent moisture and a clearing
sky early Tuesday morning are good conditions for fog formation in
valleys and basins.

&&

.DISCUSSION...
Issued at 158 AM MST Mon Nov 2 2026

Light rain showers continue from areas around Muddy Gap to
northwest Natrona County as of 08Z (1AM) this morning, with
additional showers near Dubois and Pavillion in the Wind River
Basin. North to northwest winds with gusts of 30 to 40 mph have
also developed across areas east of the Divide in the last hour
or so as the main sfc low has now moved over western portions of
SD/NE. This trend (of winds and precipitation) will continue
through the rest of the day today as the main storm system
continues its eastward progression over the Northern/Central
Plains. The highest amounts of precipitation will occur through
the morning hours (focused over areas east of the Divide as well
as Sweetwater County) as most of the supporting upper level
dynamics will have shifted well to the east by 18Z. Natrona and
southern portions of Johnson County are expected to receive the
highest amounts, ranging between 0.20 to 0.50". Winds will
increase over western portions by 12Z, with gusts of 25 to 35
mph, before decreasing after 18Z. At the same time, gusts of 50
to 60 mph will develop over northern portions of Johnson County
and continue through much of the day. This remains in line with
the current High Wind Warning for northern Johnson County that
is in effect through 3PM. Snowfall amounts remain largely
unchanged, with Winter Weather Advisories for the east slopes of
the Wind River and Bighorn Mountains in effect through 5PM.
Advisory amounts of snow (6") for Casper amounts are still on
the marginal side with confidence remaining too low to issue an
Advisory at this time. Overall, it will be a cloudy and windy
day across the CWA today with daytime highs in the 40s.

Winds will decrease through the evening as the gradient begins
to weaken and the main storm system continues its eastward
progression. Gusts up to 35 mph will continue over much of
Johnson County through the night. Clouds will also begin to
scatter out from west to east in the evening. Possible fog
formation will be a concern Tuesday morning as a result,
especially for areas east of the Divide. Precipitation amounts
today will likely help drive this from occurring.

Conditions are expected to remain dry through the rest of the
week. An area of high pressure will settle over MT Tuesday and
keep temperatures at or slightly below normal and winds light.
This high center will also keep a weak Pacific system to the
south over UT/CO Wednesday, with the main impact being mainly in
the form of cloudy skies over southern/southwestern portions.
The pattern briefly becomes more active by Thursday as another
weak trough moves over the Northern Rockies and a second cold
front clips northeastern portions of the state on Friday. High
winds look possible again over northern Johnson County in the
wake of this front, with a 110 to 120kt jet supporting the
front. Wind looks to be the main impact with this front for now
with conditions remaining dry through the weekend as a strong
ridge moves over the Northern Rockies into Alberta/Saskatchewan.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1019 AM MST Mon Nov 2 2026

Scattered light rain continues mainly east of the divide this
morning, and will slowly fade through the early afternoon. A few
showers are drifting in the vicinity of KJAC right now, so added
brief mention, but cigs there should remain above 4000. Rain
should end at KRIW/KLND by 21Z, with light rain/drizzle at KCPR
through sunset. Mostly clear skies most likely overnight, but
have some concern for fog/low cloud formation. Plenty of surface
moisture from precip the past 24 hours has low levels saturated,
so colder temperatures could condense near the sfc pretty
quickly. Signal from models is very low, but atmosphere is well
primed for it, so have started with some VCFG at the most prone
locations KJAC/KBPI/KPNA to start, and will monitor trends for
increased confidence.

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 5 PM MST this afternoon for
WYZ009-015.

&&

$$

UPDATE...Wittmann
DISCUSSION...LaVoie
AVIATION...Straub