564
FXUS65 KRIW 132241
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
341 PM MST Thu Nov 13 2025

.KEY MESSAGES...

- Dry and mild today, with gusty winds (25 to 35 mph) from South
  Pass to Casper.

- Showers return to western Wyoming on Friday, with isolated
  strong wind (55+ mph) possible in areas like Casper and the
  Lee of the Absarokas.

- A cooler and wetter pattern begins Sunday, lasting into next
  week, though details on timing and placement of rain and snow
  remain uncertain.

&&

.UPDATE...
Issued at 1146 AM MST Thu Nov 13 2025

No notable updates to the forecast for today. Temperatures are quite
warm for mid-November, with highs across the area in the upper 50s
to mid-60s. Gusty southwest winds occur from South Pass to Casper,
generally 25 to 35 mph. These winds also occur across the Absaroka
and Wind River Mountains, as well as portions of Yellowstone. A
shortwave is still projected to move through tonight and tomorrow,
increasing winds for those previously mentioned locations (with
lesser increases elsewhere). Rain/snow chances will also increase
across the western mountains and valleys after 2am MST, with the
best chances Friday afternoon. Overall amounts have not changed
much. The highest elevations of the Wind River Range have
increased slightly, but still only up to about 5 inch totals.

&&

.DISCUSSION...
Issued at 251 AM MST Thu Nov 13 2025

All in all, things look to remain quiet today as ridging will remain
in place over the area for Thursday as well. The only concern will
be gusty wind in the favored southwesterly flow areas, like Casper,
but with 700 millibar winds only around 30 knots, high wind is not
expected. Temperatures will remain very mild as well, in some cases
over 20 degrees above normal. A few places, like Casper, will make a
run at 70 and could break a record high today.

Things finally begin to take a more active turn on Friday as a
Pacific trough approaches the area. As for precipitation, this looks
more like a nuisance event then anything. The system does not have a
lot of moisture to work with. Ensemble guidance gives at most a 1
out of 3 chance of 3 inches or more of snow snow from Friday through
Friday night and this is only in the southern Absarokas where
impacts are small to non existent. Temperatures also look to remain
fairly mild, with 700 millibar temperatures only falling to possibly
minus 2, which would keep snow levels at 7500 feet or higher and
away from the valleys. The main concern looks to be wind. The jet
will be close to the Montana border, putting much of the area in the
favored right front quadrant for downward forcing. The 700 millibar
winds are borderline though, only around 40 to 45 knots when I would
like to see 50 to 55 knots. The areas with a greater than 1 in 2
chance of wind gusts past 55 mph are generally restricted to the
higher elevations. I could see a stray gust over that in a place
like Wyoming Boulevard, but not widespread enough for any
highlights. The threat of higher wind should end Friday evening as
the trough moves through and the pressure gradient relaxes. This
will also bring a warm day, probably the warmest day of the period.
The best chance of seeing a 70 degree high is Friday, and if this
occurred at Casper, it would be the third latest 70 degree high
temperature in station history.

Ridging will build back over the area on Saturday, and bring a
mainly dry and somewhat cooler but still mild day. The next
potential weather maker then moves in for Sunday as an upper level
low moves onshore over California and moves toward the Cowboy State.
This system looks potentially more interesting as as it crosses the
Rockies to could bring lee cyclogenesis over Colorado and wrap more
moisture back into the area. There is not a lot of cold air though,
at this point this would be a rain event in the lower elevations or
possibly a rain / snow mix with snow levels remaining above 6500
feet so any impacts would be restricted to the mountains. Another
system then arrives early next week, and this one is potentially
cooler and may bring the first accumulating snow to the lower
elevations East of the Divide. However, upper level lows are
notoriously hard to forecast, especially in regards to details this
far out. So, although confidence is high in a transition to a cooler
and wetter pattern next week, confidence is still very low in
regards to the details of placement and amounts of precipitation.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 341 PM MST Thu Nov 13 2025


VFR flight conditions continue through the entire TAF period with
mid to high clouds. KCPR is expected to be the windiest terminal,
with gusts ranging from 25kts-35kts most of the TAF period. At all
other terminals, winds are forecast to be 10kts or less during the
overnight hours. Winds increase with gusts of 20-30kts after 16Z
Friday at all terminals except KWRL. Strong winds aloft could also
cause instances of LLWS after 09Z at KCPR and after 17Z at KCOD.
Confidence is lower (30%) in LLWS at KJAC, so there is no mention at
this time.

There is a 30% 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. Mountain
obscuration could occur around KJAC and KPNA.

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...Wittmann
DISCUSSION...Hattings
AVIATION...Gerhardt