558
FXUS65 KRIW 182258
AFDRIW

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

.KEY MESSAGES...

- Isolated showers will persist over portions of the Bighorn
  Basin and Bighorn Mountains today into tonight.

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

- The weather pattern will favor cool 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 out ahead of it late
this week into this weekend. Some of the energy from the low out
ahead of the cut-off 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 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 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. 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 /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 358 PM MST Tue Nov 18 2025

Broken to overcast VFR ceilings are expected to persist at
terminals through tonight as additional moisture and clouds
spread into the area from the south. The mountains around KJAC
will see light precipitation chances increase around 12Z, though
confidence on terminal impacts remain on the lower side. Have
introduced a PROB30 group during the most likely period for
impacts through the Wednesday afternoon hours. Otherwise, KCPR
will see a breezy southwest wind through the period, with all
other terminals remaining under 10 knots.

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...Myers