813
FXUS65 KCYS 021803
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1103 AM MST Tue Dec 2 2025

.KEY MESSAGES...

- A High Wind Warning has been issued for the wind prone areas
  of southeast Wyoming beginning Monday evening and continuing
  through noon Tuesday.

- A Winter Weather Advisory has been issued for the Sierra-Madre
  and Snowy ranges for Tuesday morning through Wednesday
  morning.

- Long term remains active with multiple systems promoting
  prolonged periods of high winds, light snow and cold
  temperatures.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 259 AM MST Tue Dec 2 2025

Active weather is expected over the next 36 hours as an arctic front
brings much colder temperatures, light snow accumulations and high
winds to portions of the CWA. Ahead of the front, high winds will
continue into the early afternoon as MSLP gradients remain steep.
The GFS currently has 700 mb winds at about 50 to 55 kts with strong
subsidence. This is enough to get high winds blowing at Arlington
and the South Laramie Range early this morning. In-house guidance as
well as the GFS have winds peaking before sunrise this morning. High
winds will likely continue through the morning hours before
easing this afternoon as the cold front begins to push into the
CWA. Lift from the approaching front and increasing mid-level
moisture will likely lead to some scattered light snow showers
throughout the day. Accumulation with this first round of
showers is unlikely, except in the high terrain, where Winter
Weather Advisories go into effect this morning and continue
through Wednesday morning.

The arctic front will begin to push into the CWA from the north
later Tuesday evening. Along and behind the front, more widespread
precipitation is expected. Most precipitation will fall overnight,
leading to snowfall accumulations for portions of the forecast area.
Most models and ensembles are in very good agreement regarding
snowfall totals, giving confidence in the forecast. Outside of the
mountains, the highest totals will likely be along the Interstate 80
corridor between Cheyenne and Rawlins. Winds will be northerly
behind the front, leading to upslope flow and orographic enhancement
of snowfall totals for the Laramie Valley, central Carbon County,
and the Arlington area. About 1 to 2 inches of snow will be possible
in these areas. Outside of these zones, most other locations can
expect anywhere from a dusting to an inch of accumulation.

Light snow will likely continue through Wednesday morning before
tapering off. Accumulations will still be possible Wednesday morning
with the aforementioned locations still expected to be in upslope
flow. Snow will taper off early in the afternoon, but cold
temperatures from the arctic front will remain. High temperatures
will only be in the 20s, with wind chills expected to be in the
teens most of the day. Even colder temperatures and wind chills are
expected overnight. Overnight lows will be in the teens and single
digits, with wind chills below zero for most locations before
sunrise on Thursday.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 308 PM MST Mon Dec 1 2025

Mean northwest flow aloft looks to persist through the period with
hints of shortwave ridging intermittently putting a damper on what
seems to be near daily snow chances across the Snowy and Sierra
Madre ranges. Current ensembles and clusters paint this picture well
with a shortwave ridge both on Thursday and Monday passing within
the vicinity of the forecast area though slight variations exist in
the amplitude and track that could impact the nightly radiational
cooling potential (Thursday AM lows in the single digits to teens).
After a chilly Thursday morning highs climb back near freezing in
the afternoon.

High winds look to return Friday after a quiet few days wind-wise
Wednesday/Thursday with the in house guidance showing a greater than
60 percent chance for high wind criteria in the typically wind prone
areas. This is expected to be a long duration event with the 700mb
jet between 45-55kts per clusters and a tightening pressure gradient
working to get these winds to the surface. At the same time things
look to turn wintry once again by Friday afternoon in the mountains
with several inches likely in the Snowy and Sierra Madres through
Sunday as more shortwave activity brings moist flow to the higher
elevations. However once again shadowing effects are likely going to
limit how much accumulation we can produce outside of the high
terrain. Near average temperatures continue into the weekend as we
feel the impact of ridging (and the embedded shortwave activity on
its eastern periphery producing the snow) keeping highs in the 30s
and 40s through the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1052 AM MST Tue Dec 2 2025

Breezy conditions expected over the next several hours, though
winds have been under performing at most TAF sites. Still,
expect the potential for winds gusting 15-25 knots before
relaxing later this evening. A system then moves in and brings
lowered cloud decks alongside chances of snow showers, with MVFR
to IFR potential CIGs and VIS, but conditions could locally
deteriorate to LIFR status under heavier snow or even lower
cloud decks.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 5 PM MST this afternoon for WYZ106-116-
     117.
     High Wind Warning until 8 PM MST this evening for WYZ110.
     Winter Weather Advisory until 11 AM MST Wednesday for WYZ112-
     114.
NE...None.

&&

$$

SHORT TERM...SF
LONG TERM...TJT
AVIATION...CG