964
FXUS65 KRIW 291809
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1109 AM MST Sat Nov 29 2025

.KEY MESSAGES...

- The remainder of today is dry and cold, with highs in the
  upper teens to low 20s for most of the area.

- A weak weather system brings light snow to western and
  southern Wyoming Sunday. Most of that area should see an inch
  or less, with isolated areas up to 2 inches. Southern Lincoln
  County could see up to about 3 inches.

- Multiple weak weather systems are expected through the coming
  week, bringing light snow chances and keeping temperatures
  cool to seasonal.

&&

.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 /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1018 AM MST Sat Nov 29 2025

The last of the low clouds from overnight snow has eroded in the
past hour, with only high cirrus drifting overhead across the
state. This cirrus will continue to increase as the next weather
system sweeps in overnight tonight. Cloud cover will increase
and lower through the night for sites west of the Divide,
reaching low MVFR/IFR levels by tomorrow morning. Have not yet
added precip to these sites, as this may not occur until 18Z/30.

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...Straub