418
FXUS65 KCYS 080531
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1131 PM MDT Tue Oct 7 2025

.KEY MESSAGES...

- Isolated ares of fog are possible Wednesday morning.

- Warmer and drier conditions prevail for Wednesday and
  Thursday, but precipitation chances return for Friday into
  the weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 202 PM MDT Tue Oct 7 2025

Current VIS satellite imagery shows a plume of clouds pushing north
from Colorado and clipping the southeast corner of the CWA, with
the leading edge from Cheyenne to Bridgeport in Morrill County.
A weak surface low in Colorado is at fault and expect these
clouds to linger for most of the afternoon with gradual clearing
during the evening as the low weakens. Well, what about the rest
of the CWA, many locations are basking in sunshine under clear
skies. This is a result of an upper level ridge that is building
across our region. This ridge will be the dominate feature for
the short term period as weather conditions overall will remain
relatively benign. Expect generally light winds across the CWA
today due to a laxed pressure gradient with high pressure to our
east. However, overnight we will see winds ramp up from the
south which may bring more clouds into our CWA and/or increase
chances of another shot at fog, especially south of a line from
Laramie to Sidney. The clouds that are currently in place along
with stronger winds that develop overnight may limit any
potential fog development by Wednesday morning. Out west,
across Albany and Carbon Counties, dry air is in place and skies
will remain clear today into tomorrow. Ridging will continue to
amplify through Wednesday, this will bring warmer 700 MB
temperatures of 10 degrees Celsius. This translates to surface
temps that will top out in the upper 60s west of I-25 and low
to upper 70s east of the corridor. Lows tonight won`t be as cold
as Monday night with temps bottoming out in mid 30s to mid 40s,
warmest across the Nebraska Panhandle. On the fire weather
front, the development of breezy southerly winds may lead to
locally elevated fire weather concerns for Wednesday. However,
many locations across the CWA has seen wetting rains recently
which will dampen most of the concerns.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 212 PM MDT Tue Oct 7 2025

Not a whole lot of changes in the long-term forecast with this
afternoon`s model guidance. Ridging still looks to dominate the
forecast on Thursday with the warmest day of the forecast period on-
tap. Forecast highs will run 10 to possibly as high as 20 degrees
above average throughout the day as mid-level temperatures reach
their peak underneath the ridge axis. One caveat to this warm
forecast will be the advancing cloud shield from the west, which
could make it into southeast Wyoming by mid to late afternoon which
may limit highs here. Farther east however, all systems are go for
highs into the mid-80s in the NE panhandle.

Attention quickly turns to our next weather maker - the remnants of
Hurricane Priscilla in the eastern Pacific. This tropical system
will make its way up the Baja coast on Friday. At the same time, a
large closed-low pressure system will continue to spin off the
Pacific Northwest coast of the USA. Southwesterly flow will
transport a notable moisture plume northeastward through the Four
Corners region and into Wyoming and Nebraska by Friday afternoon and
evening. Expect mild overnight lows with a large and thick cloud
shield in place. Precipitation on Friday still looks to remain
rather light and limited to upslope regions in the Southeast Wyoming
mountains given poor lapse rates and rather warm mid-level
temperatures.

Despite rather high precipitable water values, surface precipitation
chances remain rather low (around 30% or less) through Saturday
despite the proximity of the remnants of our tropical system and the
advancing upper-level low. Warm mid-level temperatures and extensive
mid and upper-level cloud cover will severely limit instability and
with a vertically stacked upper-level low to the west, not much in
the way of significant forcing will spread east over southeast
Wyoming and western Nebraska. Therefore, expect a mild but cloudy
pattern to continue through the weekend with the best chances of
light rain or showers limited to the mountains. By Sunday, a cold
front looks to march eastward through the Great Basin and Front
Range/High plains as a new shortwave helps push the upper-low out of
the western CONUS. Ensemble guidance is quite dispersive with timing
and strength of this front at this range, with some members pushing
the front through early on Sunday morning and others holding this
system off until Sunday evening. However, there is fairly high
confidence (above 60%) that a cooldown is in store by Sunday night
into early next week as most guidance does show below average 500mb
heights by this time. Precipitation chances are much less certain
from Sunday through the rest of the week, especially east of the
Laramie range where low and mid-level flow does not look favorable
for upslope precipitation. Expect a few tenths of an inch of
precipitation in the mountains with rain changing to snow behind the
front in the Sierra Madre and Snowy Ranges on Sunday. A slushy 1-2
inches is possible by Monday in these higher-elevation regions with
a return to below-average temperatures and dry weather east of the
Laramie Range on Monday.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1127 PM MDT Tue Oct 7 2025

The possibility exists for another round of fog heading into
Wednesday morning. The highest chance for this is at KLAR,
KCYS, KSNY, and KBFF with probabilities ranging from 10% to 50%
for IFR conditions. Confidence is pretty low as a result, but
the probability is high enough to warrant TEMPO groups at KLAR
and KSNY, and VCFG at KCYS and KBFF. Expect all terminals to
return to VFR by the late morning hours.

Gusty winds return Wednesday, with southwest gusts at KRWL and
KLAR, and southerly gusts at all other terminals. Wind gusts of
20 to 30 knots can be expected. This may continue after sundown
at KCDR and KAIA.

&&

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

&&

$$

SHORT TERM...RZ
LONG TERM...MAC
AVIATION...MN