756
FXUS65 KCYS 192238
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
338 PM MST Wed Nov 19 2025

.KEY MESSAGES...

- Models continue to alternate on the strength and placement of
  a low later this week, but expecting at least some
  precipitation and snow with this system, mainly south of the
  North Platte River Valley. Snow accumulation will be possible.

- First real shot of cold air could arrive as early as next
  week, with high temperatures possibly in the 20s and 30s.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 332 PM MST Wed Nov 19 2025

A challenging forecast is expected over the next 48 hours as a storm
system begins to move into the region. Thursday, during the day,
will actually be relatively quiet. The weak ridge axis over the CWA
will push eastward as the strong trough swings into the Rockies. As
a result, part of the day could feature some sunshine before clouds
move in and thicken later in the afternoon. This bit of sunshine
along with 700 mb temperatures above 0C will lead to high
temperatures a few degrees above average. Most of the day will
remain dry until precipitation starts moving in late in the
afternoon as cyclogenesis takes place.

Both the GFS and ECMWF show leeside cyclogenesis occurring
Thursday afternoon in southeast Colorado. Previous runs of these
models placed the surface low in the same location but ejected
it eastward along the Kansas/Oklahoma border. Newer runs track
the surface low more northeasterly into west-central Kansas
where the system stalls for roughly 12 hours before ejecting
eastward. This change in track, albeit slight, does pose
substantial differences in impacts for the CWA. While the
southerly track posed little to no impacts for the CWA, the
northerly track will allow for higher QPF amounts from wrap
around moisture. Now that this storm is finally entering into a
timeframe where Hi-Res guidance can pick up on it, Hi-Res seems
to be in agreement with the more northward track. The HRRR is
the fastest out of the Hi-Res models, moving precipitation into
the southeastern part of the CWA my mid afternoon. Other models
are more keen on moving precipitation in during the evening
hours. Regardless of what time precipitation moves in, the bulk
of it will fall overnight. For most of this event, the eastern
half of the CWA will be in easterly upslope flow, allowing for
efficient precipitation generation. Models show the highest QPF
amounts along the Interstate 80 corridor between Cheyenne and
Sidney. Here, models and ensembles show anywhere from a quarter
to a half inch of QPF. The biggest forecast challenge lies in
whether this QPF will fall mostly as rain or snow, and if snow,
how much accumulation. Most models, both deterministic and Hi-
Res show little to no snow accumulation. This is likely because
the correct wet bulb temperatures will not be achieved to
generate snow. Even most ensemble members for both the GFS and
ECMWF do not show snow accumulations for cities east of the
Laramie Range. Both the 12Z and 18Z HRRR remain the biggest
outlier for this event, showing over Warning level snow
accumulations for most of Laramie County. This seems a bit
aggressive, but if more models start to come on board it is not
out of the question. For now, nudged snowfall totals along the
Cheyenne Ridge towards the NBM and HREF Grand Ensemble. These
models show about an inch of accumulation in these areas which
seem realistic given the current set-up.

Precipitation will continue into the day Friday as upslope flow
continues east of the Laramie Range. Nudged temperatures below
NBM guidance as precipitation and ample cloud cover will likely
cause temperatures to stay fairly steady throughout most of the
day. Precipitation will taper off by the evening hours. For now,
held off on issuing any products as confidence is still low
regarding accumulation with this system. Hopefully future shifts
will gain more clarity if models come into better agreement
with snowfall totals.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 332 PM MST Wed Nov 19 2025

This weekend a weak ridge sets up after Friday`s system continues to
push east. Temperatures look to maintain in the 50`s and 60`s east
of I-25 and 40`s to 50`s west of I-25 into the higher terrain.
Forecasted clear skies will allow radiational cooling to maximize
and drop the overnight temperatures to drop into the 20`s. Monday,
the Intermountain west will another southern system traverse the
region. The models are still a little uncertain in the placement of
the storm track but some models are showing a quicker more northern
track than others. If the more Northern solution occurs then some of
the southern counties may see some light precipitation however if
the more southern solution happens then the most likely outcome will
be cloudy skies and no precipitation. Tuesday morning, a deep trough
will begin to descend into the region with a cold front pushing
through to produce some needed precipitation for the region.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1017 AM MST Wed Nov 19 2025

VFR conditions are expected through the TAF period however, with
the easterly winds forecasted for the Panhandle there could be
some early morning fog between 12z and 18z tomorrow. Otherwise
winds in the afternoon should start gusting here shortly wind
light winds projected tomorrow.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.

&&

$$

SHORT TERM...SF
LONG TERM...MM
AVIATION...MM