158
FXUS65 KRIW 290928
AFDRIW

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

.KEY MESSAGES...

- Snow ending and wind decreasing today for a dry but cold day
  today.

- The next system brings light to southern and southwestern
  Wyoming Sunday into Sunday evening.

- An active pattern for next week with a couple of chances of
  light snow for portions of the area.

&&

.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 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 as well, 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 of 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. And tonight will be the coldest of the season for
many, especially East of the Divide where most areas have at least a
1 in 2 chance 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 is the Salt and
Wyoming Range, 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
1 in 4 chance anywhere in 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 average near to
slightly below normal through much of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 930 PM MST Fri Nov 28 2025

IFR to MVFR ceilings with light snow and gusty winds behind the
cold frontal passage. BPI/PNA/COD/WRL should be done with
snowfall at the start of this cycle by ongoing elsewhere
further south and east. RKS/LND should be done by 08Z, RIW by
09Z, and CPR by 10Z but still lingering around through mid
Saturday morning by 16Z. Ceilings will lift to VFR after the
snow ends respectively and scatter out by 12Z at most
locations. Upper level clouds will continue to spill across the
state from the upper level ridge to the west increasing in
coverage after 00Z Saturday evening ahead of the next wave for
Sunday.

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 8 AM MST this morning for WYZ010-
011-020.

&&

$$

DISCUSSION...Hattings
AVIATION...Lowe