241
FXUS65 KCYS 171102
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
502 AM MDT Fri Oct 17 2025

.KEY MESSAGES...

- High Wind Warnings remain in effect through 6 AM Saturday for
  the wind prone regions of southeast Wyoming.

- A strong cold front will move through Saturday leading to
  freezing temperatures across the entire region Saturday night
  into Sunday morning.

- A series of clipper systems will impact the region on Saturday
  and on Monday with another round of strong winds and some rain
  and snow mix possible down to 6000 feet.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 235 AM MDT Fri Oct 17 2025

Mostly quiet tonight across southeast Wyoming and western Nebraska.
Many locations along I-25 and I-80 have been gusting between 55 and
62 mph most of the evening as strong downsloping winds return. Other
locations are seeing mostly calm winds. Cool temperatures in the 30s
and 40s as of 08Z, but locations experiencing downsloping are the
warmest tonight. Some lower clouds have moved in across Carbon
County and northern Albany County. These clouds are expected to
remain through the overnight and early morning hours.

No majors changes to the short term forecast tonight as the upper-
level trough slowly moves across the region, with a strong cold
front expected Saturday afternoon. The pper-level trough will be off
to the east of the CWA by Sunday afternoon. For Friday, the 700mb
low over the northern Plains will keep 700mb height gradients tight
throughout the day, leading to a strong 700mb jet around 48 to 50
kts. By midday today, the 700mb low will be far enough to the
northeast that 700mb winds will begin to decrease as the height
gradients weaken. This brief lull in strong winds will only last
about 6 hours, before 700mb height gradients strengthen once more.
Surface winds will begin to increase around 00Z, but will really
ramp up by midnight tonight when the 700mb jet strengthens to 50 to
55 kts overnight. With strong downward omega values across the
region, strong winds will easily make it down to the surface.
Despite the 6 hour lull this afternoon/evening, decided to extend
the High Wind Warnings to 6am Saturday and mentioned the brief lull
from about noon through 6pm today.

Saturday afternoon, a strong cold front will traverse from north to
south across the CWA, resulting in high winds in the wind prones
begin cut off as wind directions flip to northwesterly, a less
favorable direction for strong winds. Winds will remain breezy
behind the front, but high wind chances should drop off dramatically
with the cold frontal passage. 700mb temperatures behind this cold
front will tank into the -9 to -6C range, leading to a cool day
Saturday with highs in the 40s and 50s. Some precipitation will
accompany this front in the form of rain and a rain/snow mix for
some locations. The biggest question at this time is how much
downslope drying will limit precipitation reaching the surface.
Extended the PoPs down into the southern reaches of the CWA, but
kept PoPs fairly low in the 15 to 25 percent range with the
uncertainty in low-level drying. An even colder night is expected
across the region, with overnight lows Saturday into Sunday in the
upper-20s to 30s across the entire CWA. Guidance is favorable for
freeze potential in the final three zones that have not reached
freezing temperatures yet this year. Decided to hold off for now on
issuing any Freeze Watches as some zones are borderline at this
time. However, future model runs may further solidify the need for a
Freeze Watch, so pushed the decision to the day shift for now.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 325 PM MDT Thu Oct 16 2025

Periods of active weather expected in the long term as we see
clipper systems bringing precipitation and winds to the region
during the weekend and again early next week, with the potential
for a brief quieter period into the middle to later portion of
next week to end the long term. Saturday begins as the first
aforementioned clipper moves into the region, bringing early
precipitation followed by gusty winds and cold morning lows into
Sunday. Currently, ensembles are indicating we should be a bit
too warm to produce lower elevation snow with this quick hit of
moisture in the morning, so for now expect morning rain and high
elevation snow for our western zones, though with QPF amounts
lacking, significant accumulations are unlikely. Pressure
gradients tighten and we`ll see an enhanced jet at the mid and
high levels, leading to high confidence in another high wind
event for our wind prone regions. In house guidance is in good
agreement on this, showing similar high confidence on the
potential for gusts 58+ mph. Sunday morning lows should be
chilly behind the cold air mass this system brings, with
widespread lows around or just above freezing, but clear skies
from a transient ridge will let us warm with highs back into the
60`s to mid 70`s.

Monday another quick moving clipper system brings more
precipitation and notably cooler temperatures which could lead
to a higher chance of mid to lower elevation snow, though
confidence at this time still remains low. And forecasts
indicate amounts once again won`t be high with the quick moving
nature of this system, so overall accumulations shouldn`t be
significant. But another stout jet accompanies this system, once
again promoting a moderate to high chance of high winds for our
region with agreement coming together yet again from our in
house guidance. The cold air that follows this system is
expected to promote a widespread morning freeze on Tuesday
morning, with temperatures in the mid to upper 20`s across most
of our Wyoming zones, with low 30`s in the Nebraska Panhandle.
After that, the forecast becomes quiet to end the long term
period, with another transient ridge on Tuesday followed by a
weaker trough on Wednesday that isn`t currently producing
noteworthy impacts based on NBM guidance. Overall there is
moderate to high confidence in the overall forecast as ensemble
clusters remain in good agreement on the features and their
general strength and placement through the long term period.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 502 AM MDT Fri Oct 17 2025

Some low-level clouds are in place across KRWL with ceilings firmly
in the MVFR category, bordering on IFR as of 11Z. Clouds should
begin to clear after sunrise, with conditions improving to VFR in 1
to 2 hours. After this, mostly clear skies expected for the 12Z TAF
period with upper-level clouds encroaching multiple terminals later
this evening. Primary aviation concern will be the strong, gusty
winds expected at all terminals this afternoon. Gusts between 25 and
35 kts are expected, with a locally higher gust possible at KRWL and
KLAR. Winds will remain strong throughout the evening and overnight
hours.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 6 AM MDT Saturday for WYZ106-107-110-
     116-117.
NE...None.

&&

$$

SHORT TERM...AM
LONG TERM...CG
AVIATION...AM