603
FXUS65 KCYS 130349
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
849 PM MST Wed Nov 12 2025

.KEY MESSAGES...

- Warming trend continues through Thursday with temperatures
  increasing a few degrees each day. Dry conditions will
  continue through the end of the week.

- A trough will move into the area later this weekend with
  chances for precipitation and cooler temperatures.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 300 PM MST Wed Nov 12 2025

Conditions remain dry and warm in the short term under high
pressure ridging. For tonight, a cloud bank will move into the
region and help insulate our temperatures, with overnight lows
in the 30`s to mid 40`s outside of the mountains. Then on
Thursday, expect the warning to continue, as we see well above
normal highs in the 60`s to mid 70`s as the ridge continues to
transition overhead. A quick shortwave will move into the region
by Friday from a larger system to the north in Canada, and the
tightening pressure gradients alongside a weak mid level jet
should bring gusty conditions to our wind prone locations.
Currently the bulk of the 700mb winds look to remain around 45
knots or so, and in-house guidance is indicating we`ll approach
high wind criteria but not quite hit it. Therefore much like the
previous update, will continue to not advertise headlines for
high winds late Thursday into Friday, but will continue to
monitor the latest guidance.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 300 PM MST Wed Nov 12 2025

Unseasonably warm temperatures will continue into Friday as strong
ridging aloft remains in place over the area. With warm air
advection peaking ahead of a weak Pacific trough passing to our
north, we should see the warmest temperatures of the week on Friday
supported by 700-mb temperatures around +5 to +7C. Look for
widespread highs some 15 to 20F above average for this time of year
in the 60s to as high as the mid to upper 70s in the Nebraska
panhandle. Daily record highs are currently forecast for Sidney and
Alliance, while most other locations are within a few degrees of the
daily records. In addition to the warmth, expect winds to return to
the wind prone areas as the pressure gradient tightens ahead of the
next system. 700-mb height gradients are un-impressive and surface
pressure gradients are marginally supportive of high winds. In-house
guidance is showing probabilities around 40% for high winds during
the Friday morning period. Due to the marginal support, the official
forecast does not yet reach high wind criteria, but the winds were
still increased above NBM guidance since at least some gusts of 50
to 55 mph appear likely.

Ensemble guidance has coalesced around the split trough solution for
this weekend`s pattern change. The northern branch trough will pass
to our north Saturday, but models have trended further north with
this, such that it may not even be much of a cold front. High
temperatures are forecast to drop perhaps 5 to 10F off of Friday`s
values for Saturday, but this will still be 10 to 15F above
climatological normals. Conditions will remain breezy to windy, but
the direction should change from Friday`s southwest to west or
northwest on Saturday. Precipitation will be quite limited with this
first trough, if anything falls at all. Low end PoPs are retained in
the mountains, but moisture and forcing are expected to remain well
to our north.

The second piece of this split trough will be a powerful closed low
left over the California coast this weekend. This will approach the
area Sunday into Monday as the upper level low ejects across the
Rockies. Winds will ease Sunday ahead of the system, but expect
highs to remain about 10F above average for this time of year. Since
this will be a closed low underneath a fairly strong ridge, it will
be running into a very warm airmass and will not have access to any
cold air from the north. Therefore, once precipitation begins, we
may have unusually high snow-levels in place for this time of year,
possibly beginning as high as 10 kft. While the probability of a
significant precipitation event remains low, ensembles are
converging on a light to moderate precipitation event for much of
the area. Probabilities for 0.1" or more or liquid precipitation in
the Sunday through Monday period have increased to about 40 to 60%
over the High Plains, and 60 to 80% along and west of the Laramie
Range. Due to the high snow levels, the probabilities for one inch
or more of snow are quite a bit lower, around 5 to 20% for Wyoming
population centers and 10% or less in Nebraska. Still, it is very
difficult to bet on an all rain event in November, so the official
forecast was tweaked to bring a mention of rain/snow mix to all
areas above 5500 ft in elevation. While the probability of
accumulation is not very high, 700-mb temperatures look marginally
supportive of at least some snowflakes mixing in. The average snow
level through the event appears to be around 8000 ft in the current
ensemble suite, so we anticipate some modest accumulating snow to
fall in the mountains. Current probabilities suggest a 50 to 70%
chance for advisory criteria snow totals in the Snowy and Sierra
Madre ranges, and a 20 to 40% chance for warning criteria amounts,
mainly only for the highest peaks.

This system appears likely to break the warm and dry weather
pattern, ushering in a much more active pattern with a train of
Pacific upper level lows possible through much of next week. The
details of this pattern remain highly uncertain, but expect to find
more seasonable temperatures and more regular chances for rain and
snow heading into the last third of November.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 900 PM MST Wed Nov 12 2025

Overcast skies are likely overnight at all terminals however
ceiling heights will remain well above MVFR thresholds with
mainly high cirrus expected. Westerly winds will resume on
Thursday with VFR expected for all terminals. No major impacts
to aviation are expected in the forecast period.

&&

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

&&

$$

SHORT TERM...CG
LONG TERM...MN
AVIATION...MAC