369
FXUS65 KRIW 300335
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
835 PM MST Sat Nov 29 2025

.KEY MESSAGES...

- A weak weather system brings light snow to western and
  southern Wyoming Sunday. The heaviest snow falls between 9 AM
  and 3 PM and produces amounts of one inch or less. Isolated
  areas in Sweetwater County could see up to 2 inches, while
  south Lincoln County may see 2 to 3 inches.

- A clearing sky Sunday night allows for single digit lows for
  most lower elevation locations. Seasonal average overnight
  lows range from the lower to mid teens.

- Multiple weak weather systems are expected through the coming
  week, bringing light snow chances and keeping temperatures
  cool to seasonal. The best chance for widespread light snow
  appears to come Tuesday and Tuesday night.

&&

.UPDATE...
Issued at 1108 AM MST Sat Nov 29 2025

With snow moving out of the area, the rest of today remains dry.
Current satellite shows most of the area in white, though southwest
Wyoming remains brown (no snow). This should change tomorrow as a
weak system brings snow chances across western and southern Wyoming.
Latest models have west of Divide locations generally seeing an inch
or less, with isolated areas closer to 1.5 inches where heavier snow
showers occur. Highest totals are expected over the Salt/Wyoming
Ranges (2 to 4 inches) and into the lower elevations of southern
Lincoln County (1 to 3 inches). Isolated areas close to 4 inches
could also occur (20 percent chances).

Sunday afternoon, some gusty north-northeast winds, 25 to 30 mph,
occur over I-80. With snow chances, this could cause some minor
winter travel conditions through the evening.

&&

.DISCUSSION...
Issued at 217 AM MST Sat Nov 29 2025

Winter has finally arrived and punched many locations in the mouth
Friday night. It was rather nasty when I arrived for my shift;
snow with wind gusts close to 50 mph. As I write this before 2
am, snow is still ongoing across portions of the area, mainly
the eastern portions. We should see the worst of this through
around 3 am, with improving conditions following that as the
front continues to move south away from the area. All snow
should be over by sunrise, if not before. As for wind, it
continues to be quite strong, especially in the northwest flow
locations. Buffalo and Greybull are continuing to have gusts to
around 50 mph, although they are decreasing elsewhere. We may
be able to cancel the Advisories somewhat early, if the wind
decreases a bit earlier than expected.

The main story today will be the cold temperatures, the coldest so
far this season. This will especially be the case in areas that saw
some accumulating snow, adding the assist from the fresh snow
increasing the albedo and the weak late November sun having a
limited effect. Most locations will stay in the 20s and some
areas in the teens. Tonight will be the coldest night of the
season for many, especially east of the Divide where most areas
have at least a 1 in 2 chance of lows falling into the single
digits. Increasing high clouds late tonight should keep most
locations above zero though.

The aforementioned clouds will be coming from the next wave that
will largely impact southern and southwestern Wyoming, as it
drops in from Idaho. This wave is also a fast mover and has
even less moisture to work with than last nights wave, and the
best dynamics remain to the south and west of Wyoming.
Probabilistic guidance shows even less snow than yesterday. The
only location with a greater than 1 in 2 chance of 2 inches or
more are the Salt and Wyoming Ranges, with only a 1 in 4 chance
of 4 inches. The lower elevations from Afton through Rock
Springs have around 1 in 3 chance of an inch or so of snow. As
for east of the Divide, a few showers may jump the Divide, but
any amounts should minuscule. All snow from this system should
end by midnight Sunday night.

Transitory ridging should bring a dry and somewhat warmer day for
Monday. The next system then drops in on our fast moving northwest
flow for Monday night and Tuesday. There continues to be some model
disagreement on the details of the system, but there is greater than
a 1 in 2 chance of some locations getting some snow from this
system, although probabilistic guidance also shows there is less
than a 1 in 4 chance anywhere in the lower elevations of 3
inches or more, so right now it is not looking like a major
storm. Another wave may approach for the end of the week, but
details are impossible to determine this far out. Temperatures
look to moderate to near normal to slightly below normal
through much of next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 416 PM MST Sat Nov 29 2025

VFR conditions continue through Saturday evening, with only
high cirrus increasing aloft from the west ahead of the next
weather system. This system spins to our west and south,
bringing increasing impacts to airports west of the Continental
Divide Sunday morning. The main impacts will reach KBPI/KPNA
mid-morning, with MVFR/IFR cigs and vis in combination with
light snow into early afternoon. KRKS will see quickly lowering
cigs late Sunday morning, and will be in low clouds and -sn
through the rest of the day. KJAC forecast is trickier, as it
will be on the edge of the system as it passes. Current forecast
keeps the airport out of the low clouds and precip, but have
kept a PROB30 for a modest chance of brief morning snow
showers. East of the Continental Divide, cigs fall to low-end
VFR heights at KLND/KRIW briefly in the afternoon. KCPR will
also be on the edge of the lower cloud deck, but chances remain
low for any MVFR cigs.

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.

&&

$$

UPDATE...Wittmann
DISCUSSION...Hattings
AVIATION...CNJ/Straub