754
FXUS65 KCYS 052324
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
424 PM MST Fri Dec 5 2025

.KEY MESSAGES...

- High wind warnings in effect tonight through Saturday for the
  wind prones and areas immediately along the lee side of the
  Laramie range

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

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

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 322 PM MST Fri Dec 5 2025

Tough forecast in the short term as we see one round of high
winds and winter conditions give way to a second round. High
wind warnings from this morning were ended early as conditions
had subsided, but a fresh batch of warnings have been issued for
a much larger area as we are expected to see a stronger wind
event across the CWA. Models highlight a very strong 700mb jet
moving into Saturday morning around 12Z, with a 60-70 knot
maximum from Arlington through the Cheyenne area alongside
favorable downward omega values to bring these winds to the
surface, and coinciding with strong cross pressure gradients
through the region to also favor these expected high winds. In
house guidance continues to agree, with probabilities of 40-90%
across these areas, highest in our usual wind prone locations.
Because of this, high wind warnings from Rawlins along I-80 to
Cheyenne and up into Bordeaux have been issued from this evening
through Saturday afternoon.

Meanwhile, have continued the winter products that were already
issued, including the Winter Weather Advisory for the Arlington
area that does coincide with the high wind warning for
overnight into tomorrow as well. While snow on the ground plus
fresh falling snow could promote periods of lowered
visibilities, current expectation from similar past events is
that we will not achieve visibilities below 1/4 of a mile for 3
hour sustained periods, precluding the need to upgrade to a full
on blizzard warning in this area. Still, expect that this snow
and wind could dramatically reduce conditions and cause
hazardous travel across this zone. Otherwise the mountains look
on track to achieve this criteria, with the heaviest snow
expected overnight tonight as a surge of moisture alongside snow
ratios in excess of 15:1 helps to fuel nearly a foot of new
accumulation. Expect a fairly robust system to continue our
early December wintry pattern, but a warmup is on the way in the
long term.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 322 PM MST Fri Dec 5 2025

Variability remains in ensemble guidance in the exact placement of
the upper jet streak but all guidance does meander the jet over the
region with transient shortwave activity being the primary driver of
its position and orientation. There will be a 500mb jet of 100-
120kts frequently over the area and 700mb flow regularly over 50kts
and occasionally over 60kts. The GFS remains on the higher end of
guidance with flow over 70kts at times. With that said there is
above average confidence this far out in High Wind Warnings being
issued during the Tuesday to Thursday period in the wind prones with
a mentionable signal for high wind potential extending into adjacent
zones and event the front range at times.

Associated with the shortwave activity that will drive the wind
potential will be a few surges of moisture that bring high elevation
snow (up to a foot above 8000ft) and a dusting to the front range
from Tuesday morning through Wednesday afternoon. One thing to look
forward to in the long term for those that still are not quite ready
for winter will be temperatures that are much more seasonal with
highs in the 40s and 50s below 7500ft. For those areas above 7500ft
expect highs in the 20s and 30s through the coming week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 434 PM MST Fri Dec 5 2025

Light snow will slowly bring ceilings back down in RWL over the
next 6 hours today with MVFR from about midnight to sunrise.
Winds frequently gusting over 30-40kts in RWL, LAR, and CYS by
06z onwards and 20-30kts for Nebraska sites after 06z. Wind
shear will be prevalent for all sites (minus possibly AIA and
CDR) beyond midnight, predominately Westerly or NW in direction
and 35-50kts in magnitude. Other than RWL and LAR all sites
staying above MVFR thresholds for visibility and ceiling but
still seeing ceilings drop to 4-8kft for most at some point in
the period.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning from 8 PM this evening to 5 PM MST Saturday
     for WYZ106-109-110-116.
     Winter Weather Advisory until 5 PM MST Saturday for WYZ110.
     Winter Storm Warning until 5 AM MST Sunday for WYZ112-114.
     High Wind Warning from 2 AM to 5 PM MST Saturday for WYZ115-
     117.
     High Wind Warning from 2 AM to 2 PM MST Saturday for WYZ118.
NE...None.

&&

$$

SHORT TERM...CG
LONG TERM...WFOCYS
AVIATION...WFOCYS