260
FXUS65 KCYS 041136
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
436 AM MST Thu Dec 4 2025

.KEY MESSAGES...

- Winds will pick up again Thursday morning in the wind prone
  areas. Another round of High Wind Warnings have been issued.

- Areas of blowing snow Thursday may impact travel conditions
  in the wind prone areas of southeast Wyoming.

- Prolonged period of mountain snow expected Thursday night
  through Sunday Morning. Winter Storm Warnings have been issued
  for Sierra Madre and Snowy Ranges.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 253 AM MST Thu Dec 4 2025

Active weather continues in the short term with high winds and
mountain snow returning to the CWA. Early this morning, patchy
freezing fog keeps popping up and dissipating. Light winds with
clear skies and moisture from snow on the ground has contributed to
the sporadic fog. This will likely continue through about sunrise,
when winds are expected to increase. Besides fog, the clear, calm
conditions and snow have contributed to very cold temperatures.
Single digits as well as below zero temperatures have been
observed out west in valley locations. These temperatures will
heat up relatively quickly once the wind picks up.

Today, High Wind Warnings are in effect for the usual southeast
Wyoming wind prones through Friday morning. Weak disturbances aloft
will traverse the CWA, causing MSLP gradients along and west of the
Laramie Range to steepen. 850 and 700 mb CAG to CPR height gradients
will also strengthen, causing winds aloft to increase up to 55 kts.
Strong subsidence will also exist, helping send these winds down to
the surface. Although parameters are marginal, in-house guidance is
quite confident in high winds occurring, with over 80 percent
probabilities of high winds at Arlington and the South Laramie Range
between now and early Friday morning. Although it will be windy,
downsloping winds will not be enough to combat the cold temperatures
expected again today. It will be warmer than yesterday, but high
temperatures will still be in the 20s and 30s for the majority
of the CWA with perhaps a few low 40s sneaking into the North
Platte River Valley.

High winds will continue into Thursday night, with mountain snow
returning to both the Sierra Madre and Snowy Ranges. Northwest flow
will funnel Pacific moisture into the CWA for several days, leading
to a prolonged mountain snow event. Issued a Winter Storm Warning
for the mountains starting tonight as 1 to 2 feet of snow could be
possible over the next few days. Opted for a long duration Warning
as strong winds are expected over the next few days and there did
not appear to be any real lull in snow as well. Snowfall rates will
be rather impressive at times, especially in the Sierra Madre Range
as orographic lift dominates. The Winter Storm Warnings continue
through Saturday night.

Mountain snow will continue into the day Friday with mid-level
moisture being funneled in the CWA. A brief break in high winds is
expected during the day, but chilly temperatures will remain in
place with highs mainly in the 30s. A stronger upper-level
disturbance arrives Friday night, likely leading to another high
wind event for the wind prones and potentially wind prone adjacent
areas.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 245 PM MST Wed Dec 3 2025

Ensemble clusters continue to depict northwest flow across the
central and northern Rockies through next week with slight
variations in the zonal vs meridional component by early next week.
Overall with ridging centered over or just offshore southern
California and dominant troughing in the Canadian Maritimes it does
not look to be a particularly amplified pattern the next several
days with low amplitude shortwaves keeping active precipitation
chances in the mountains which occasionally spill into the adjacent
zones and high plains through the period. Temperatures will
gradually warm through the end of the period with highs on the front
range and NE panhandle reaching into the 50s early next week. Most
notably through the extended will be periods of high to very high
winds especially early next week.

- Snow Chances

The high elevation snow that starts on Friday in the Snowy and
Sierra Madre ranges will continue through the weekend with the bulk
of the snowfall coming on Saturday and tapering off on Sunday.
Elevations above 7000ft in the Sierra and 8000ft in the Snowy can
expect greater than 6" from Friday to Sunday and 1-3 feet for areas
over 9000ft elevation. A few more weak shortwaves then rotate
through the northwest flow later in the period bringing more chances
for light snow to the higher elevations but the snow shadow should
be in effect for the front range with only a dusting expected
through the extended period.

- Wind, Wind, and More Wind

Breezy for some of the high elevations on Saturday though not sold
on high wind criteria just yet as in house guidance shows things
improving markedly from the high wind warning that is in effect from
Thursday morning into Friday morning. Currently looking at a 20-40%
chance for high wind criteria for that Saturday surge. Looking
further ahead to early next week 700mb flow of 50-60 kts and as high
as 70-75 kts combined with deeply negative omega will bring strong
winds to the surface early next week. Ensembles certainly support
this with mean gusts ranging from 50-60 mph on the low end for the
wind prone areas with this being another long duration event lasting
from Monday well into the heart of next week. There is even a
greater than 30% chance that lower elevation areas on the front
range like Cheyenne proper get in on the fun by Tuesday.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 435 AM MST Thu Dec 4 2025

Lingering low stratus in the southern Nebraska panhandle will likely
dissipate by mid-morning. Main aviation concern today will be strong
gusty winds at southeast Wyoming terminals. West winds with gusts
over 30 kts will be possible throughout the day. Strong winds will
continue overnight. Clouds will also build in overnight as snow
moves into the mountains out west. Overall, VFR conditions are
expected at most terminals for the majority of the TAF period.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 6 AM MST Friday for WYZ106.
     High Wind Warning until noon MST Friday for WYZ110-116.
     Winter Storm Warning from 11 PM this evening to 5 AM MST
     Sunday for WYZ112-114.
NE...None.

&&

$$

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