533
FXUS65 KRIW 171135
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
435 AM MST Tue Feb 17 2026

.KEY MESSAGES...

- Active today with moderate snow in western Wyoming this
  morning and strong to high wind across much of the area.

- Another weather system brings more widespread light to
  moderate snow from Wednesday through Thursday morning.

- The coldest temperatures in some time move in Thursday and
  should last through at least Saturday.

&&

.DISCUSSION...
Issued at 228 AM MST Tue Feb 17 2026

Active weather has returned to western and central Wyoming and a we
have little to talk about and a lot of time to do it. Wait, strike
that, reverse that, I mean we have a lot to talk about and little
time to do it. For a change, we will split the discussion
differently. With around an active 54 hours or so, we will tackle
each day individually, talking about each hazard individually. So,
let us begin.

Snow...Today and tonight...Snow has already begin across the west,
with Jackson reporting snow as of 1 am along with many of the
western mountains. As for this forecast, the advisories so far look
to be on track and we will not make many changes this morning.
Timing of the greatest impacts still looks to be through this
morning, with the most before 9 am as the trough axis and cold front
move through the area. One thing the day shift may consider is if
they could cancel the advisory a bit early, as most of the snow may
be over by noon. Amounts still look reasonable as well. There has
been a bit of drop, but there is still around a 1 in 2 chance of 3
inches or more in the valleys. And this, combined with the expected
strong wind, should bring enough impacts to warrant them. Amounts
still look reasonable in the mountains as well, with a greater than
1 in 2 chance of 6 inches or more in the areas with the advisories.
Chances of 12 inches of snow are fairly small though and largely
limited to the highest elevations where impacts would be minimal.
Elsewhere, we are still watching for possible brief heavy snow in
Sweetwater County, this would best be handled with short term
statements. As for East of the Divide, any showers would be limited
except for the mountains, like the Bighorns which may see a few
inches. In addition, the screaming downslope (that sounds like a
good name for an alternative rock band of meteorologists) should
keep any showers to a minimum. The best chance would be around
Casper but anything here should be brief. A last area of concern
this afternoon may be in northern Johnson County, where some
snow showers may develop with the front and bring a small
accumulation. Following that, there should be a lull before the
next system approaches from the west after midnight, but any
snow amounts should be light until Wednesday.

Wind...Today and tonight...We have already had some high wind gusts
tonight, with gusts past 60 mph in Lander, Buffalo and Rock Springs
already. We do have a good setup for high wind with the trough and
front moving through along with some strong 700 millibar winds up to
60 knots. Around noon today, we will also have a 24 millibar
northeast to southwest pressure gradient from around Gillette to
Evanston. In the realm of probabilistic guidance, the NBM ensemble
gives a greater than 4 in 5 chance of wind gusts past 55 mph across
the warned area, with some of the more wind prone areas having a 1
in 2 chance of wind gusts past 70 mph. As a result, we will keep the
high wind warnings as is. Guidance is also showing a fairly decent
drop in the wind after around 5 pm, so the timing of the endings
still look good as well.

Fire...Today...There will continue to be elevated fire weather
across much of the area East of the Divide this afternoon. Dew
points could get very low this afternoon, falling into the
single digits. However, temperatures will be falling at the same
time. Nevertheless, there could be brief periods of critical
fire weather this afternoon in Natrona and Johnson Counties.
However, we feel that wind is the greater threat right now. We
have include wording of rapid fire spread this afternoon though.
Conditions should improve tonight as the wind decreases.

Snow...Wednesday and Wednesday night. The second piece of energy in
the form of an upper level low opening into a negatively tilted
trough will swing across the area at this time. Snow should increase
in intensity across western Wyoming. More highlights look likely as
well, with at least a 1 in 2 chance of inches of snow or more in the
Jackson and Star Valleys and at least a 5 in 6 chance of 6 inches or
more across the western mountains. Like this system, the chance of
12 inches or more is less than 1 in 5 except across the highest
elevations, so it looks more like advisories than warnings. In
addition, there would be less wind with this system. The heaviest
snow here should end early in the evening, and then our attention
shifts to East of the Divide. At this point, this looks like the
best chance of seeing some accumulating snow that we have had in a
couple of months. For reference, the last time Casper had an inch of
snow was December 27th. At our other two snow sites, Lander and
Riverton, it has been since December 3rd. Snow will spread into the
area starting Wednesday afternoon, although the steadiest snow
still looks to fall at night. This is when low level low should
turn easterly and allow more moisture to flow into the area. Most of
the area has at least a 9 out of 10 chance of an inch of snow or
more. The area of the heaviest snow is still somewhat in flux
though, and it all depends on the movement of a mesoscale 700
millibar low and its exact position. And there are still model
differences. At this point, the best chance of 3 inches or more
would be east of a Worland to Riverton line. The chance of 6 inches
or more looks fairly limited at this time. The best chance is near
Casper where there is around a 2 in 5 chance of 6 inches or more,
with the best chance in the mountains. The chance of 12 inches
remains very low though. We will likely need advisories East of the
Divide for Wednesday night and possibly into Thursday morning before
the snow tapers off.

Following this, quieter weather should return for Friday and the
weekend. A weak system may bring some further snow showers for the
northwestern mountains Friday, but any amounts should be on the
light side. The next question is temperatures. Temperatures on
Thursday will be coldest we have seen in a while, especially at
night with the fresh snow cover and decreasing wind. The air mass is
Pacific though, and that will keep bitterly cold temperatures away.
However, below normal temperatures look likely through at least
Saturday. Following that, ridging should build back over the area.
One question is for inversions in the basins, we will likely have
some initially. However, they may not last. It will be late
February, with the sun angle back to the equivalent of mid to late
October. With any sunny skies, snow would melt quicker than if this
occurred during January, and therefore weaken the inversions.
However, most areas East of the Divide  should have at least a few
days of winter weather, something that has been sorely lacking this
season.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 433 AM MST Tue Feb 17 2026

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

An incoming system will bring snow and wind to the area through much
of the period. MVFR to IFR impacts are expected, especially through
the morning hours when snow is most persistent. West to southwest
wind will continue to ramp up during this time, with gusts to 30
knots at KJAC, and 35 to 45 knots at KBPI, KPNA, and KRKS. Wind will
decrease between 00Z and 03Z Wednesday with lighter wind expected
through the end of the period. VFR conditions are expected at all
terminals by sunset. However, the next system will follow quickly,
returning snow and MVFR conditions to KJAC after 05Z.

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

A system will bring wind and some precipitation impacts to the area
through much of the period. Wind gusts of 40 to 50 knots will be
widespread, generally out of the west or southwest, strongest this
morning through 00Z Wednesday. Rain and snow is largely expected to
remain over the mountains, though brief impacts are possible at KCPR
and KLND this morning. Skies will become scattered or few by 00Z,
with lighter wind then expected through the rest of the period.

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

&&

.FIRE WEATHER...
Issued at 228 AM MST Tue Feb 17 2026

Strong wind and low humidity will bring elevated fire weather to
many areas East of the Continental Divide this afternoon. Brief
periods of critical fire weather will be possible this afternoon
in Johnson and Natrona Counties as well. Fire weather concerns
should end tonight and tomorrow as cooler and wetter weather
moves into western and central Wyoming.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST this afternoon for
WYZ001-012>014-023-024.

High Wind Warning until 5 PM MST this afternoon for WYZ002-003-
009>011-015>018.

High Wind Warning until 7 PM MST this evening for WYZ019-020-
030.

&&

$$

DISCUSSION...Hattings
AVIATION...Myers
FIRE WEATHER...Hattings