161
FXUS65 KRIW 190445
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
945 PM MST Tue Nov 18 2025

.KEY MESSAGES...

- There is a 10% chance for showers, mainly over the western
  mountains, tonight and Wednesday.

- Temperatures will be slightly warmer Wednesday for most of
  the area. This excludes western valleys.

- The weather pattern will favor cooler and mostly dry
  conditions for the rest of this week into this weekend as
  weather systems miss Wyoming to the south.

- There is a slight chance (10-15%) for some light rain/snow for
  southern portions of the area Thursday night into Friday.

&&

.UPDATE...
Issued at 1231 PM MST Tue Nov 18 2025

It is a bit warmer today and that will continue Wednesday thanks to
high pressure, but there will be enough cloud cover to prevent highs
from reaching values of last week. This means highs will be in the
50s east of the Continental Divide and 40s west of the Continental
Divide. There remains much uncertainty in regards to the weather
pattern and system late this week into this weekend. A mid-level low
will become cut-off and merge with another low upstream of it
late this week into this weekend. Some of the energy from this
second low may move far enough north to bring some light
rain/snow to southern Wyoming Thursday night into Friday, but
the chance remains low (10-15%) at this time. There will not be
much wind with this weather pattern as temperatures will remain
consistent preventing a tightening of the pressure gradient.

&&

.DISCUSSION...
Issued at 207 AM MST Tue Nov 18 2025

A soggy start to the week across the Cowboy State as Monday saw
periods of showers throughout the day. Isolated to scattered showers
will linger through the first half of the day. The best chances (20-
40%) for precipitation this morning remains over western WY. Central
parts of the state see lesser chances around 20%, with coverage
decreasing throughout the morning into the early afternoon. One
thing to monitor this morning will be the potential for some
areas of patchy fog. Due to the recent precipitation there is a
surplus of moisture currently sitting across the state. The best
chances (10- 30%) for some fog development looks to be across
western valleys such as Jackson Hole and Star Valley. Isolated
fog cannot be ruled out east of the Divide in portions of the
central basins this morning. Skies remain partly to mostly
cloudy which should limit any daytime heating. More seasonable
temperatures are forecast today with highs ranging from the 40s
west of the Divide and 50s east of the Divide.

The remainder of the week looks rather quiet and fall-like. Around
seasonable temperatures will persist with highs in the 40s west of
the Divide and 50s east of the Divide through the next couple
of days. An upper level low over the southwestern CONUS may push
moisture into the region throughout the week. This could lead
to some isolated showers at times with the best chances (10-30%)
being over portions of western and southern WY. Overall, things
will be mostly uneventful as multiple disturbances will track
too far from the area to see any noteworthy impacts here.

Models have come into better agreement regarding the aforementioned
upper level low currently over the southwestern CONUS. The consensus
looks to have this low shift more east than north, leading to little
to no impacts as a result. The next disturbance that digs south
from the PACNW by the second half of the week is starting to
look like it may do the same. Models have this low dig well too
south of the region by the weekend, resulting in little to no
impacts for the state as well. Instead, some weak ridging tries
to build in for the weekend, which would lead to seasonable and
mostly quiet weather prevailing into the start of next week.
While many snow lovers and ski resorts may be quite disappointed
by the string of bad luck regarding the lack of snow east and
west of the Divide to start the season, there is some hope. Long
range models do keep the jet stream active with multiple
disturbances moving across the western CONUS throughout next
week. So at this time, there is still way too much uncertainty
to really have a grasp on what we can expect. However, due to
the jet stream remaining active and the influx of energy all we
need is the right setup and track to possibly see some snow.
With that being said, those who are wanting some snow should
probably start looking for four leaf clovers to maybe increase
those chances.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 940 PM MST Tue Nov 18 2025

Broken to overcast VFR ceilings will continue across areas west
of the Continental Divide through the TAF period. This will
include mountain obscurations over the western mountains as
well. There is a 20% chance for VLIFR ceilings to return again
over the Jackson Valley after 12Z. Skies will be more scattered
over the valley Wednesday morning than they were on Tuesday, so
there is a chance conditions repeat in the morning. There is a
10% chance for showers over the western mountains through 18Z.
Have continued the PROB30 group in the KJAC forecast for rain in
the afternoon. Additional PROB30 groups were added for
KBPI/KPNA for showers between 23Z and 03Z. Ceilings look to drop
to MVFR at KJAC, KBPI and KPNA by 03Z in the wake of these
showers. SCT-BKN FL100-200 will be common east of the Divide
through the forecast. Winds will be light (10kt or less) at all
terminals through the forecast, with sustained winds around 12kt
at KCPR through 23Z.

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...Rowe
DISCUSSION...Dziewaltowski
AVIATION...LaVoie