383
FXUS65 KRIW 131127
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
427 AM MST Thu Nov 13 2025

.KEY MESSAGES...

- Another dry and mild day today with a gusty wind from Muddy
  Gap through Casper.

- Showers return to western Wyoming on Friday, with strong wind
  possible (a 1 in 2 chance) in areas like Casper and the Lee of
  the Absarokas.

- A cooler and wetter pattern likely begins on Sunday and lasts
  into next week, but details on timing and placement of rain
  and snow remain highly uncertain.

&&

.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 /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 425 AM MST Thu Nov 13 2025

VFR conditions through the next 24 hours, with only mid to high
level cloud cover increasing this afternoon. Winds will
increase later this morning for KCOD/KCPR/KJAC/KRKS, with gusts
generally 20 to 25kts through the afternoon. Lighter winds
return overnight tonight.

&&

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

&&

$$

DISCUSSION...Hattings
AVIATION...Straub