913
FXUS65 KRIW 141121
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
421 AM MST Fri Nov 14 2025

.KEY MESSAGES...

- Strong wind from Muddy Gap through Casper and the Lee of the
  Absarokas today.

- Light snow returns to the northwestern mountains today and
  this evening.

- More record high temperatures are possible today.

- There will be a transition into a cooler and more active
  pattern starting Sunday and continuing into next week.

&&

.DISCUSSION...
Issued at 251 AM MST Fri Nov 14 2025

More active weather has finally returned to the area after a long
lull. And, we have two concerns today, nothing earth shattering, but
something to talk about. That is why we write these discussions of
course. An approaching Pacific trough is the cause of this.

The first concern is snow. Radar shows some echoes over Idaho and
these will spread into western Wyoming this morning, although the
steadiest precipitation would be during the afternoon and early
evening. The best forcing looks to remain to the north, and as a
result so will the best snow. This will only be a concern for the
northwestern mountains. And, the chance of 3 inches or greater is at
most 1 out of 3 and this is in the Absarokas where impacts would be
slim to none. There is little no cold air with this system as well,
with 700 millibar temperatures only falling to minus 1, which would
keep snow levels to 8000 feet or higher. So, no highlights will be
needed. Downsloping flow should keep areas East of the Divide
largely dry though. But this leads into the second and possibly
greater concern.

And this concern is strong wind. We did give some thought to  a high
wind warning for Natrona County today. The 700 millibar winds have
increased to around 50 knots at times. There will also be an 110
knot jet moving across northern Wyoming, with that region in the
favored right front quadrant of it. It is a bit too far north though
for ideal forcing. As for the ensembles, the National Blend of
Models only gives around a 1 in 4 chance of wind gusts past 55 mph
along the south side of Casper, which is the main region of concern
in regards to impacts. Criteria is also higher here, needing gusts
to 65 mph. With this, we have decided to not issue. There could be
an isolated gust to 60 or 65 mph, but at this point this seems to be
the exception. The time of greatest concern may be this morning,
with gradually improving conditions later this afternoon. The
downsloping flow will also bring another unusually warm day, with
temperatures 20 degrees above normal. Some locations, like Casper,
could make a run at 70 with most lower elevations East of the Divide
having at least a 3 out of 4 chance of high temperatures over 60.

Ridging then builds back over the area for Saturday, bring a dry
day. Temperatures will be somewhat cooler, but still well above
normal for this time of year. The next weather maker in the form of
an upper level low moving northeastward from California will bring
the next chance of showers, this one more widespread than the system
today. There is somewhat better agreement today with the highest
amounts of precipitation across northern Wyoming with wrap around
moisture from a low developing in the Lee of the Rockies. Amounts
don`t look excessive at this time though. Temperatures will be
cooler with this system, but 700 millibar temperatures generally
remain above minus 4 through the period, so again it looks like
mainly rain for the lower elevations. There are still differences in
timing of the heaviest precipitation though, spanning anywhere from
later Sunday night through Monday evening. We will likely then see
more typical November weather, with near normal temperatures and a
few chances of rain and snow, although details are still fuzzy this
far out.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 417 AM MST Fri Nov 14 2025

VFR flight conditions are expected for most of the TAF period.
KCPR will be the windiest terminal, with gusts ranging between
25 knots to 35 knots with a 1 in 3 chance of gusts over 40
knots until at least 03Z. Winds increase with gusts of 20-30 kt
by 18Z at all terminals except KWRL. Strong winds aloft will
lead to LLWS over the western mountains at the start of the
forecast period, before spreading to KCOD by 14Z.

There is a 1 in 3 chance of light rain at KJAC between 21Z-00Z
Friday afternoon with an associated lower chance (20%) for MVFR
ceilings. However, given the low confidence in exact timing and
location, PROB30 group reflects these precipitation chances.
Marginal MVFR ceilings will remain in place over KJAC and KPNA
after 00Z. Mountain obscurations will develop over most of the
western mountains this morning and remain in place through
Friday night.

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.

&&

$$

DISCUSSION...Hattings
AVIATION...Hattings