383
FXUS65 KCYS 141121
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
421 AM MST Fri Nov 14 2025

.KEY MESSAGES...

- A High Wind Warning has been issued for the Arlington/Elk
  Mountain and Bordeaux wind prone regions for Friday morning
  through Saturday morning.

- A Red Flag Warning has been issued for the Nebraska Panhandle
  for Friday morning and afternoon for low RH and gusty winds.

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

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 119 AM MST Fri Nov 14 2025

Mostly clear skies tonight with only a few high level clouds moving
across western portions of the region as of 08Z. Clear skies across
western Nebraska have lead to cooler temperatures than originally
expected as temperatures are currently in the mid-30s to low-40s,
while temperatures are in the mid-40s to low-50s across western
portions of the region under the cloud cover. Gusty winds are
ongoing in the Arlington/Elk Mountain area as well as some
occasional gusts near Bordeaux. These winds are expected to increase
to high wind criteria winds over the next few hours.

Another fairly quiet weather day is expected for Friday as upper-
level ridging remains in place across the Intermountain West.
Temperatures will be quite nice today, in the 60s and 70s
everywhere. During the day today, an upper-level trough will dip
south into southern Canada and far northern portions of central
CONUS, leading to increasing height gradients and jet speeds
throughout the atmosphere. These increased gradients and jets will
result in the strong winds expected across the typical wind prone
region this morning into the afternoon and evening hours. 700mb
height gradients really begin to strengthen by 12Z this morning,
with a westerly 50 to 55kt jet expected to develop across the
Laramie Range and a subsequent 45 to 50kt jet over the Snowy Range
near Arlington/Elk Mountain. Surface pressure gradients will also
increase through the morning hours as a surface trough attempts to
develop across the region. Pressure gradients across the Laramie
Range and Snowy Range will be around 3 to 4mb. GFS Omega fields
continue to be favorable for strong, downward motion across the
mountain ranges, leading to continued confidence in elevated to high
wind criteria winds in the Arlington and Bordeaux wind prone zones.
Additionally, in house random forest guidance suggests around a 55
to 60% chance for high winds at Arlington and around a 45 to 50%
chance at Bordeaux. Therefore, the High Wind Warning for these two
zones looks good through the day today, with winds expected to
really ramp up over the next hour or two. A brief lull is expected
for the Bordeaux wind prone zone as several parameters shift to
unfavorable locations throughout the day before switching back into
favorable locations for strong winds. In addition to the High Wind
Warning today, a Red Flag Warning has been issued across western
Nebraska as gusty winds and very dry conditions return to the
Panhandle.

Another mostly quiet day is expected for Saturday, though the upper-
level pattern will begin to shift through the afternoon and evening
hours. Initially, upper-level ridging will remain firmly in place as
the next upper-level low slowly spins into western California by
early Saturday afternoon. The upper-level ridge over the CWA will
tilt back to the west as the upper-level trough across southern
Canada and the incoming upper-level low over California squeeze
upper-level height gradients and tilt the ridge to the west. The
first impacts of the approaching upper-level low from California
will begin Saturday evening as cloud cover begins to increase across
the region as that upper-level low moves towards the Four Corners
Region. Precipitation is not expected until Sunday afternoon, as the
best lift and moisture take a while to reach the region. Saturday
will still be nice and warm with temperatures in the mid-50s to mid-
60s across the region. See the long term discussion below for more
information about the incoming upper-level low expected on
Sunday.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 329 PM MST Thu Nov 13 2025

The next storms system will pass well to our north on Saturday, but
recent model guidance has trended further and further north. As a
result, this has begun to look more like a wind shift as little to
no precipitation is expected, and the temperature drop will likely
only be a few degrees. Look for highs in the upper 50s to 60s on
Saturday and Sunday, which, while likely no longer challenging
record highs, will remain about 10 to 15F above average for this
time of year. Saturday will remain breezy across the area with the
threat for high winds decreasing through the day in the wind prone
areas, while winds will come down for Sunday as the next system
approaches from the south.

The closed low that gets stranded near the California coast over the
next day or two will finally make its way east across the Rockies on
Sunday into Monday. The combination of unseasonably warm
temperatures ahead of this system and a nearly saturated atmospheric
column will lead to plentiful moisture. NAEFS mean precipitable
water values exceed the 99th percentile of climatology over most of
southeast Wyoming Sunday night into Monday morning. Thus, moisture
does not look like it will be an issue with this system. However,
the lifting mechanism is messy and disorganized which is the main
uncertainty regarding precipitation amounts. While the main low
pressure system will take a favorable track for widespread
precipitation across northeast Colorado, there will be a secondary
low both at the surface and in the middle atmosphere located over
central Wyoming which will interfere with the wind field and place a
deformation zone over the area. Westerly flow before and after the
deformation zone passes over will favor orographic lift along and
west of the Laramie range, putting the highest confidence in
precipitation over that area. East of the Laramie range, we will
have some light easterly flow present, but it looks rather shallow.
The primary low will eventually take over, leading to the
development of some modest overrunning aloft, but models differ in
how quickly this will happen. The faster this happens, the more
precipitation can be expected over the High Plains (and also the
lower the snow levels will drop). Speaking of snow levels, they will
begin this event very high for the time of year as the closed low
aloft runs into a very mild airmass. Expect this to drop through
Monday as limited cold air is wrapped in, but precipitation type
will be a forecast challenge throughout the event. Most areas
outside of the mountains can expect to see rain showers to start,
with some snow likely mixing in as the storm passes. With marginal
temperatures, accumulating snow is unlikely below about 7500 ft in
elevation (about 20% chance for 0.1" or more for these areas).
Wetting rainfall probabilities are a little higher, around 50 to 80%
for 0.1" or more of liquid precipitation. Of course, the higher
elevation mountains will be all or mostly snow, so there is decent
confidence in advisory criteria (6 to 12") of snow falling in the
Sierra Madre and Snowy range mountains. Accumulating snow is also
possible over the I-80 summit (20% chance for 1" at this time), but
confidence is lower there.

Regardless of the precipitation outcome, this system will knock down
temperatures and likely they will stay down for a while after this.
Look for near average highs on Monday and Tuesday (mid 40s to mid
50s). Attention will then shift to the next storm system, which will
be another disorganized closed low taking nearly the same track
across the southwestern US during the middle of next week. This
system will not be running into as warm of an airmass, so expect
lower snow levels and colder temperatures Wednesday into Thursday.
Any accumulating snow details remain highly uncertain. This is the
favored solution amongst the ensembles at this time, but a cluster
of about 30% of members suppress this system well to the south and
keep temperatures near average through the middle of the week while
delaying precipitation until next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 419 AM MST Fri Nov 14 2025

Prevailing VFR conditions expected for the 12Z TAF period.
Primary aviation concern will be low-level wind shear in the
morning hours from 12Z through 16Z at all terminals. Wind shear
decreases after 16Z as surface winds increase to 15-20kts with
gusts between 30 and 40kts. Gusty winds will be the main concern
from 16Z onwards.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 5 AM MST Saturday for WYZ106-110.
NE...Red Flag Warning from 9 AM this morning to 5 PM MST this
     afternoon for NEZ434>437.

&&

$$

SHORT TERM...AM
LONG TERM...MN
AVIATION...AM