633
FXUS65 KRIW 031902
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1202 PM MST Mon Nov 3 2025

.KEY MESSAGES...

- Temperatures remain well above normal through the rest of this
  week, with warmest temperatures (10 to 15 degrees above normal)
  on Tuesday and Wednesday.

- Precipitation chances skirt across northern parts of the state
  (40- 60%) Monday night into Tuesday. Impacts will be limited
  with only light snowfall accumulations above 8000ft.

- Several more weak weather systems will bring chances (30 to
  50%) for rain and mountain snow showers to western WY later in
  the week into the weekend.

&&

.UPDATE...
Issued at 1200 PM MST Mon Nov 3 2025

No meaningful changes to the forecast today. High clouds will
continue to pass overhead this afternoon, with increasing mid-level
clouds across northwest Wyoming this evening into tonight as the
shortwave moves in. Rain and mountain snow (above 8k ft) will
develop Tuesday morning, with minimal amounts for the higher peaks
in YNP, the Tetons, and western Absarokas. Up to 3-5 inches of new
snow will fall at the highest elevations of the aforementioned
areas. This snow will fall between 5 AM Tuesday and 11 PM Tuesday.
With this forecast package I did increase wind for Tuesday afternoon
as wind will be 40-50 knots at 700mb. Outer Drive (WY258) could have
a gust or two that approaches the 50 knot mark, but overall the
westerly wind direction will limit gust potential there. Fire
weather conditions will be elevated beginning Tuesday afternoon
thanks to dry conditions, low Relative Humidity, and strong wind.
The long term forecast remains on track as the general weather
pattern will be embedded shortwaves in zonal flow.

&&

.DISCUSSION...
Issued at 1215 AM MST Mon Nov 3 2025

Ridging remains the dominant weather pattern for at least the next
week or so. This means zonal flow, above normal temperatures, and
relatively quiet weather. With zonal flow in November, we can expect
shortwaves to move through and bring snow to the western mountains
and that does look to occur on several occasions over the next week.

The first is the exiting shortwave this morning. Gusty winds through
the day Sunday were the main impact from that shortwave, though
there were a few very light showers as well, mainly across the
northwest part of the state. A touch of lingering low-level moisture
with WAA behind the exiting shortwave and overnight light winds and
clear skies can mean only one thing, however. Fog could develop by
sunrise this morning across portions of the region. The central
Green River Basin looks to be the most likely location to see fog
development (30 to 40% chance) with lesser confidence in Yellowstone
Park and Jackson Hole Valley (10% chance) with even lesser chances
across the Bighorn Basin. Any fog that does develop would scatter
out by late morning. Behind yesterday`s shortwave, today will also
be cooler (but still 3 to 5 degrees above normal).

Winds will start to increase this evening and overnight in the
westerly wind favored locations as another shortwave starts to move
in by Tuesday morning. Expect light snow showers across the
northwest WY mountains through much of the day Tuesday (50 to 60%
chances), decreasing Tuesday night. Snow levels look to remain
around or even above 8000ft, so any snow accumulations will be
limited to only the highest elevations. Snowfall rates will also be
limited, so over the 12 to 18 hour event, only a few inches of
snowfall is expected at those higher peaks across the Tetons,
Absarokas, and YNP. A few light rain showers across the lower
elevations of northwest WY are possible on and off through the day
Tuesday, but otherwise, impacts with this shortwave will be minimal.

The next shortwave looks to be a bit more potent (though only
slightly), and in continued westerly flow, impacts will again remain
limited mostly focused across western and northwestern WY. Yet
another similar shortwave looks to also bring more light snow to the
northwest mountains Friday, but again, impacts look to remain
minimal.

The bigger story, perhaps, will be the above normal temperatures. I
have mentioned the warm temperatures a few times, but I want to
mention them a bit more in detail. Yesterday (Sunday) saw record
warm temperatures across much of the region, including at Riverton
Airport, where the all-time November record was broken, making it
the latest ever 70+ degree day for Riverton Airport (POR dating back
to 1996). Though records are not at this time expected to be broken
the rest of the week, we will certainly come close on both Tuesday
and Wednesday. Temperatures both days will be 10 to 15 degrees above
seasonal normals. With the more persistent shortwave influence,
temperatures cool off Thursday and into the weekend, but remain
above normal.

Looking ahead, both the GFS and ECMWF indicate a high-amplitude
ridge setting up in the early part of next week, with 700mb
temps increasing to +6 to +10C, which would have the potential
to result in 70F at the surface across portions of central WY.
If that comes to fruition, it would shatter more November
temperature records. We are still 7+ days out, but that set-up
is perhaps worth keeping an eye on.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1005 AM MST Mon Nov 3 2025

VFR conditions are expected to prevail across all terminals through
the TAF period. High clouds have begun and will continue to filter
across the region this afternoon as a result of a nearing weak
disturbance. A second disturbance will begin to approach from the
west late this evening into early Tuesday morning. As a result
clouds will begin to increase over western WY with VCSH possibly
developing nearby KJAC by the end of the period.

Winds remain light for nearly all terminals through the afternoon
with increasing speeds and some directions shifts expected as a
result of the nearing disturbance later this evening. LLWS may
develop nearby KCOD and KCPR this evening between 02Z and 06Z
Tuesday with it likely improving by sunrise on Tuesday. Winds will
begin to increase across some terminals by the end of the TAF
period. KCOD, KCPR, KJAC, and KRKS are expected to see
increasing winds by the end of the period. Winds look to
increase furthermore for nearly all terminals shortly after 18Z
Tuesday. Mountains will likely remain unobscured through nearly
all of the TAF period with obscuration possibly developing
across western ranges by Tuesday morning.

&&

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

&&

$$

UPDATE...Rowe
DISCUSSION...Hensley
AVIATION...Dziewaltowski