237
FXUS65 KRIW 161659
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
959 AM MST Sun Nov 16 2025

.KEY MESSAGES...

- Scattered western mountain snow and valley rain chances
  (30-60%) through the afternoon hours today, with largely dry
  conditions elsewhere.

- Rain and mountain snow chances (60-100%) spread south to north
  across the state beginning after sunset and continuing through
  mid-day Monday. The heaviest precipitation is expected during
  the early Monday morning hours.

- The upcoming week is trending to have near normal temperatures
  and be more active (40-60% chance), specifically Wednesday
  into Thursday. There remains uncertainty in exact timing as
  well as rain and snow amounts.

&&

.DISCUSSION...
Issued at 112 AM MST Sun Nov 16 2025

It looks like the honeymoon of the unusually mild weather we
have had for the first half of November is coming to an end and
the weather will be giving us a slap back into reality. Radar is
showing some echoes across western Wyoming this morning, but
basically none are reaching the ground as of 1 am. Today
continues to look drier as guidance continues to slow the
arrival of the precipitation. As a result, we have lowered POPs
and QPF through the daylight hours. Today will be one more mild
day, especially East of the Divide which will be likely be dry
through the daylight hours. Many locations will see highs in
the 60s, likely for the last time this calendar year. A gusty
breeze will again develop across the wind corridor from Muddy
Gap through Casper, but high wind is not expected.

Precipitation will overspread much of the area between tonight and
Monday, with the steadiest and heaviest expected from midnight
through noon on Monday as the best upper level divergence and jet
support move over the state. The reasoning of the forecast
remains fairly similar to yesterday. The area of most concern
will be the Tetons where Teton and Togwotee pass have a greater
than 1 in 2 chance of 6 inches of snow or more through the
period. Given the possible impacts to travel over Teton and
Togwotee Passes, we went ahead and issued a Winter Weather
Advisory for this zone, although it was borderline. Other areas,
like the highest elevations of the Salt and Wyoming Range as
well as the western Wind River Range also have at least a 1 in 2
chance of 6 inches of snow or more. However, these are away
from the passes and with impacts expected to be limited we
elected to hold off for now. The day shift can take another look
and see if any additional highlights are needed since the
greatest impact would not be until later tonight.

This will be mainly a mountain snow event though. The 700 millibar
temperatures generally only fall to around minus 3 celsius, which
would put snow levels around 7000 feet. And this is by Monday
morning when the best lift moves out of the area. Places like
Bondurant could see a couple of slushy inches and even Pinedale
could see a slushy inch or so. The Jackson and Star Valleys
would likely only see a coating. Odds are less than 1 out of 3
for three inches in all these areas, so we will not issue any
advisories. As for East of the Divide, with 700 millibar
temperatures only falling to minus 1 celsius, snow levels should
remain above 8000 feet, with only rain for the populated areas.
There are still some disagreement on placement of the heaviest
amounts though, so we broadbrushed things for now. Most
precipitation should end from south to north starting Monday
afternoon as the upper level low moves away to the north and
east.

Cooler weather then moves in for Monday through much of next week.
However, with flow largely west or southwesterly, temperatures will
remain near to somewhat above normal through the week. Tuesday looks
mainly dry with only a few showers in northern Wyoming. Following
that, we have the same conundrum as previous days. We do look more
unsettled through the period. However, there are still large
disagreements in the guidance in regard to timing and movement of a
couple of systems moving through. So, although confidence remains
fairly high in a cooler and more unsettled pattern, details remain
highly uncertain.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 427 AM MST Sun Nov 16 2025

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

VFR conditions will persist across western terminals to start the
period. Mid to high SCT-BKN clouds are expected to gradually build
across the region today in association with a nearing disturbance.
Winds remain light from the south/west through the first half of the
period. Showers begin to move into the region around 15Z Sunday,
first at KJAC. PROB30 group is in place due to the uncertainty
regarding direct impacts from showers to the terminal. Showers
dissipate during the afternoon with the next round of precipitation
arriving after 00Z Monday. Showers may start around KRKS by 02Z with
other terminals such as KJAC, KPNA, and KBPI seeing showers by 05-
06Z Monday. Due to warm temperatures precipitation may initially
fall as rain or a mix before likely turning over to snow by the
morning hours Monday. Precipitation is expected to prevail at
western terminals through the end of the TAF period. MVFR to IFR
conditions may be possible at times due to dropping ceilings and
visibilities. Winds look to increase along with this push of
moisture leading to some terminals seeing winds of 10-15 knots
with gusts of 20-25 knots. Mountains will be obscured through
much of if not all of the the TAF period. Obscuration likely
increases by the afternoon/evening on Sunday as precipitation
increases and ceilings lower.

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

VFR conditions prevail across all terminals to start the TAF period.
Mid to high SCT-BKN clouds will continue to gradually build in over
the region throughout the day today. Winds remain light across most
terminals with KCPR being the only exception seeing winds of 15 to
20 knots and gusts around 30 knots starting by 18Z Sunday.
Precipitation begins to make its way east of the Divide shortly
after 06Z Sunday. Showers look to start developing nearby KCPR first
then chances increase at KLND and KRIW afterwards. Temperatures look
to warm for snow to fall at most terminals except for KCPR which may
see brief periods of mixing or wet snowfall at times. KWRL and KCOD
see precipitation chances increase around 10Z Monday. Precipitation
will linger across all terminals through the end of the TAF period.
Showers may produce periods of MVFR or IFR conditions especially at
KCPR, KLND, and KRIW by the early morning hours Monday. Winds
increase at KCPR and KRIW as precipitation begins to move into the
area with winds of 10 to 15 knots with gusts nearing 20 knots at
times. Mountain obscuration will gradually increase through the TAF
period especially after 00Z Monday through the end of the period.

Please see the Aviation Weather Center and/or CWSU ZLC and ZDV for
the latest information on smoke, icing, and turbulence
forecasts.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 PM this afternoon to 5 PM MST
Monday for WYZ012.

&&

$$

DISCUSSION...Hattings
AVIATION...Dziewaltowski