956
FXUS65 KCYS 291150
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
450 AM MST Sat Nov 29 2025

.KEY MESSAGES...

- An arctic front will move south of the region this morning,
  bringing much colder temperatures along with light to moderate
  snowfall to the forecast area through the weekend.

- Very active long term forecast expected with multiple troughs
  moving through and promoting snow chances, as well as a high
  wind event possible Tuesday.

- Temperatures will remain very cold through mid-week, before a
  weak warming trend arrives Wednesday onwards.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 255 AM MST Sat Nov 29 2025

Potent upper level trough and associated arctic cold front
continue to impact southeast Wyoming and western Nebraska early
this morning with strong gusty winds up to 55 mph, rapidly
falling temperatures into the teens and likely single digits
here shortly, locally heavy snowfall, and very cold wind chills
as low as 10 below zero. Periods of snowfall continue up north
along Route 26, 18, and 385 through Chadron. Winter Weather
Advisory looks good up there with blowing and drifting snow
continuing and several periods of a quarter mile visibility or
less. Further south, the main surprise has been the persistent
band of snow which is colocated with the axis of peak
frontogenesis initialized very well on the 00Z ECMWF. There has
been a pretty consistent band of moderate to heavy snow between
Laramie and Cheyenne over the past 3 hours and wouldn`t be
surprised if 3 to 5 inches of snow fell northwest of Cheyenne.
However, it should be localized enough to not need a last minute
Winter Weather Advisory. Kept the Special Weather Statement
going for local travel hazards in and around the Interstate 80
corridor from near Laramie to the Nebraska border. In fact,
Cheyenne has over-performed a bit during this system with
visibility down to one half mile in moderate snow. Snow band
appears to be weakening, but could see an additional inch of
snow accumulation by sunrise.

Wind Chill/apparent Temperatures are approaching cold weather
advisory criteria early this morning in a few locations with
readings around 10 below zero. Will continue to keep an eye on
this, but expect readings to stay above 15 below zero for the
rest of the night.

For the rest of Saturday, upper level trough axis will push east
of the region by noon today. Most high res guidance shows the
snowfall coming to an end by 600 to 900 AM, and perhaps a few
hours later for Dawes County. However, windy conditions are
going to continue for much of the day with gusts up to 40 to 50
mph. This will result in patchy blowing snow and some drifting
on area roadways, especially over the Laramie Range and the Pine
Ridge from Lusk to Chadron Nebraska. Wind Chill temperatures
will likely remain in the single digits above and below zero
for most areas. For tonight, all models show a shortwave ridge
axis building along the Front Range. This will be short-lived as
the next clipper system will dig southeast into Idaho and Utah
on Sunday. Very cold temperatures tonight with lows likely in
the single digits every where. Some below zero readings are
expected where there is snowpack, likely across east central
Wyoming and the northern Nebraska Panhandle where Chadron may
dip down under 5 below zero. Wind Chill temperatures won`t be
too bad due to the lack of wind.

Not much of a break between progressive weather systems, as
models show the next one ejecting east into Utah and eventually
Colorado. Although synoptic models show minimal to low impacts,
short range ensemble guidance and high resolution guidance show
that we need to watch this clipper closely as it moves
east...and we`ll need to monitor how far south in digs before it
marches eastward. This system will keep temperatures cold,
possibly even colder than Saturday, with highs struggling to
reach the low to mid 20s as another cold front digs south across
the region. Cloud cover will increase early Sunday
morning...limiting surface heating. The mountains and adjacent
foothills may need a Winter Weather Advisory for Carbon and
parts of Albany county for 2 to 5 inches of snow. Some guidance
shows these snow bands extending into Platte and Laramie county
as well with decent snowfall rates, so will need to watch
additional impacts east of I-25 with decent isentropic lift
ahead of the main trough axis. These systems tend to surprise
us, especially when associated with arctic airmasses. Remaining
cold Sunday night with lows back into the single digits in
periods of light snow and/or flurries.


&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 225 AM MST Sat Nov 29 2025

Previous long term forecast looks good with only a few tweaks to
POP Tuesday night and early Wednesday in addition to nudging
winds near High Wind criteria Monday night/Tuesday morning for
the wind prone areas. Adjusted wording to avoid duplication
late in the short term period.

Previous LONG TERM Discussion...
Issued at 135 PM MST Fri Nov 28 2025

Fairly active long term weather forecast for southeast Wyoming and
western Nebraska as multiple troughs dig through the region
throughout the week. As the 700mb system pushes through Sunday
night and into Monday morning, a surface trough will develop
with an attendant cold front, dropping 700mb temperatures into
the -12 to -10C range, from the -9 to -6C range, by the early
morning hours Monday. As a result, surface overnight lows into
Monday morning will remain in the single digits.

Cold conditions will continue into the day Monday as the upper-
level trough pushes over the CWA, funneling continental arctic
air from Canada into the region. The trough will begin to pinch
off throughout the day Monday as the next upper-level trough
from Canada digs into the northwestern CONUS, with very brief
ridging possible early Tuesday morning. The departing and
weakening upper-level trough will keep 700mb temperatures in the
negative single digits Monday, before a briefly warming into
the -3 to 0C range for the early morning hours Tuesday. With the
transitioning upper- level pattern, Monday will be mostly dry,
though cold. Surface high temperatures will remain in the
mid-20s to mid-30s Monday. Winds begin to increase throughout
the day Monday, with high winds possible on Tuesday. With the
cooler temperatures and increasing winds, apparent temperatures
will remain in the teens to 20s for the afternoon on Monday.
Overnight lows Monday into Tuesday will be a bit warmer, thanks
to the brief upper- level ridging expected Monday night into
early Tuesday morning. Tuesday morning lows will only bottom out
in the teens to mid-20s, much warmer than the single digits
from the night before.

The warming will be short-lived as the upper-level ridging quickly
gets shunted to the east early Tuesday afternoon and the next upper-
level trough pushes into the region. Snow chances increase west to
east on Tuesday as the positively tilted, upper-level wave moves
into the region and the CWA once again remains in the left exit
region of the upper-level jet. 700mb temperatures will tank back
into the -10 to -8C range Tuesday afternoon and evening as the
attendant cold front surges through. Prior to the cold front
arriving, a brief zonal pattern will develop across the CWA Tuesday
morning into the afternoon hours at 700mb. A brief period of
enhanced height gradients at 700mb will increase the low-leve jet to
around 50 to 55kts, with pockets around 60kts, across the Laramie
Range. Downward omega values increase Tuesday morning and afternoon
as well, leading to ample downward mixing through the day. In
addition to this, the Craig to Casper 850mb gradient increase to
over 70m, with the 700mb gradient approaching 60m. In house guidance
is very excited about this event, with a 90% probability of high
winds at Arlington and 70% probability at Bordeaux. With all these
factors combined, strong to near-high winds are likely Tuesday
afternoon in the wind-prone regions.

The remaining long term period is dominated by upper-level
troughing, cold 700mb temperatures, and daily snow chances across
the region. The previously mentioned trough stays over the region
through Friday before the next upper-level trough moves in and
pushes the aforementioned trough off the east. Temperatures for the
remaining week will warm slightly, though 20s, 30s, and 40s are
still likely across the region. In-house guidance is hinting at
another high wind potential Friday, with about a 50% probability at
this time. Things will still change between now and Friday, but did
start increasing the winds late in the period to start hinting at
the next possible high wind event across the region.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 450 AM MST Sat Nov 29 2025

Potent upper level trough will move east of the area this morning
with light snow ending from west to east. Remaining cold and windy
today with winds gusting between 35 to 45 knots until 23z.

HAZARDS/WEATHER TRENDS: Improving conditions this morning with
mostly MVFR prevailing until 16z (light snow and blowing snow), and
then VFR for the rest of the day into tonight. Periods of IFR are
possible near bands of light snow, mainly for KAIA and KCDR.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

WY...Winter Weather Advisory until 8 AM MST this morning for WYZ101-
     102.
NE...Winter Weather Advisory until 11 AM MST this morning for
     NEZ002.
     Winter Weather Advisory until 8 AM MST this morning for NEZ095.

&&

$$

SHORT TERM...TJT
LONG TERM...AM/TJT
AVIATION...TJT