541
FXUS65 KRIW 232326
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
426 PM MST Fri Jan 23 2026

.KEY MESSAGES...

- Much colder today with areas of light snow following the
  passage of an Arctic Front.

- Another front brings another chance of light snow from
  Saturday night into Sunday.

- The beginning and middle of next week looks largely dry with
  moderating temperatures.

&&

.UPDATE...
Issued at 1200 PM MST Fri Jan 23 2026

IR continues to depict the cold cloud tops across the state
wrapping around the upper level trough positively tilted across
the upper Rockies. The main finger of the PFJ will continue to
push south and southeast that will finally tap into much better
moisture as it progresses later tonight. This will be the big
impact winter weather event for the Great Plains and southern
regions of the country. As for here in our CWA, radar indicates
the light snow tapering off with its southeastward progression
this afternoon. Cloudy skies remain through sunset improving
overnight that will give way to the coldest morning low
temperatures east of the Divide Saturday morning.

The cold frontal passage later Saturday evening still on track
with minimal impact outside of the some light snow in similar
areas as today before tapering off Sunday morning. Ridging then
builds back in with dry conditions and a warming trend back to
seasonable temperatures Sunday and even above average Monday and
through much of next week. No indications of any big weather
system in the long term with mainly dry conditions the remainder
of the month and into early February.

&&

.DISCUSSION...
Issued at 250 AM MST Fri Jan 23 2026

If you live in western and central Wyoming and don`t like winter,
you have been living a charmed life so far. Well that has come to an
end this morning as an Arctic Front has dropped southward across the
area and given a slap in the face of the fine people of western and
central Wyoming and snapped us back to reality. There is also some
light snow falling across the area. We will talk about these below.

We will start with the snow. For the most part is has been light
given the very dry air mass behind the front. There has been a bit
of wind but by Wyoming standards this is nothing. Reasoning remains
similar to yesterday as well. The most impacted areas will be areas
prone to northerly flow, with an emphasis on areas east of
Thermopolis and especially around Casper where there will be a bit
of right rear quadrant jet energy to enhance the lift of what little
moisture we have. The main area of concern is Natrona County. Areas
near Casper have around a 1 out 2 chance of an inch of more of snow
but the chance of 3 inches is 1 out of 6 at most. The other area of
concern is Thermopolis to Ten Sleep with around 1 in 2 chance of an
inch of snow but being further from the jet energy the chance of 3
inches is almost zero. This, combined with wind that is not very
strong and expected to decrease through the day means impacts will
not be severe and we will not issue any highlights. There could be
some snow in southern Wyoming as well but amounts here would be
light. All snow should end in the evening as the front moves away.

And now we move on to temperatures. With the Arctic air moving in
and cloud cover lingering, temperatures will not rise much at
all today and may slowly fall, remaining in the teens and single
digits East of the Divide. This still looks to be the coldest
air of the season so far with 700 millibar temperatures falling
to around minus 20. We lowered highs several degrees as a
result. The next question is tonight, will some areas see below
zero lows for the first time this season? We are now strongly
leaning toward yes. It now appears we will see some clearing
after midnight, allowing for better radiational cooling. The
ensembles give at least a 2 out of 3 chance of lows below zero
for most locations. Areas where the cold air pools and areas
with some snow cover, like Natrona and Johnson County as well as
portions of the Bighorn Basin, have a chance to drop under 10
below zero. The next question is, do we need cold highlights?
Right now, the answer is no. The chance of lows of 20 below zero
are very small, and with wind expected to be light, most areas
will not reach criteria. It will be coldest night in quite a
while though.

Saturday looks like a mainly dry but cold day across the area but a
bit milder for some with some breezes mixing the atmosphere a bit,
especially in the wind prone areas. Then, the final in a series of
Arctic Fronts drops across the area for Saturday night. Like the
others, there is not a lot of moisture with it. This one has a bit
more jet forcing with it though. So, it looks a bit wetter than
yesterday. At this time, things still look sub advisory with
snowfall amounts with the only location with greater than a 1 in 2
chance of 3 inches or more is the western Bighorns where there may
be a bit of upslope to enhance rates a bit. With the jet, this could
be more of a banded type of snow, with most guidance favoring from
Worland through Casper. Again, this is not a major storm but will
likely be some more accumulating snow. Any snow here should end by
sunset on Sunday. It will bring some reinforcing cold air, with
another day of very cold temperatures and a cold night Sunday night.

We should then enter a quieter period as ridging builds into the
area. Temperatures are the main question here. Normally breezier
areas should mix out and see a return to near to somewhat above
normal temperatures by Tuesday. There is more of a question for the
basins where inversions may keep temperatures cooler. Still up in
the air right now. However, no major storms are expected through at
least the middle of next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 426 PM MST Fri Jan 23 2026

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

All west of the Divide terminals are forecast to remain dry and
largely VFR throughout the TAF period. Clouds are now expected to
gradually diminish through roughly 06Z to 10Z as drier air behind a
weak boundary moves into the area. However, low clouds remain
possible during this timeframe, and perhaps a few hours beyond 10Z,
at all west of the Divide terminals. Confidence in these low clouds
being dense enough to cause MVFR flight conditions is between 20% and
30%. Given this lower confidence, VFR flight conditions are being
maintained at this time but the potential is reflected in a SCT015,
SCT030, or FEW030 group. Otherwise, expect relatively light winds
much of the TAF period. Winds increase and become breezy late in the
TAF period, especially at KPNA and KBPI where gusts between 20 kts
and 25 kts are forecast.

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

At KCPR and KWRL, light snow and any associated reduced flight
conditions are expected to diminish by 01Z, with MVFR clouds
lingering a few hours longer at KCPR. Confidence has increased to
around 40% in MVFR flight conditions at KRIW and KLND to start the
TAF period. There is higher confidence that MVFR ceilings will
persist at KLND through the overnight hours compared to KRIW. All
east of the Divide terminals can expect dry conditions a majority,
if not the entire TAF period. The exception is KCOD where there is a
30% chance of light snow along a cold front after 22Z Saturday.
Winds remain relatively light throughout the TAF period. Mountain
obscuration is expected through at least 02Z around KCOD and 09Z
around KCPR.

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

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...Lowe
DISCUSSION...Hattings
AVIATION...Gerhardt