461
FXUS65 KCYS 291113
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
513 AM MDT Fri Aug 29 2025

.KEY MESSAGES...

- Scattered precipitation chances continue for Friday and
  Saturday, though drier conditions are expected to return
  Sunday onwards.

- Warming trend starts Sunday, with fire weather concerns slowly
  creeping up to start the work week.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 154 AM MDT Fri Aug 29 2025

A slightly different story tonight as much of southeast Wyoming is
experiencing clear to mostly clear skies, while western Nebraska
remains socked in with low clouds. Some patchy fog has developed
sporadically across southeast Wyoming, though most locations remains
un-impacted. Temperatures are cooler tonight across southeast
Wyoming with the clearing skies. Most locations are seeing
temperatures in the 50s, while temperatures in the Panhandle remain
in the 60s. Winds are also a little stronger tonight through a few
pockets of light and variable winds remain.

The upper-level ridge across the Intermountain West will remain
largely in place today, with westerly flow across the region under
the northern portion of the ridge. An upper-leve trough is slowly
advecting eastward today and will be the primary forcing mechanism
for afternoon showers and storms. 500mb flow continues to favor
monsoonal moisture advecting into the region, leading to another wet
day with dewpoints into the 50 and 60s for locations east of the
Laramie Range. With monsoonal moisture remaining in the region, the
Weather Prediction Center has highlight the CWA in a Marginal Risk
of excessive rainfall once again for today and tomorrow. 700mb flow
remains mostly weak today, though an increasing height gradient this
evening into the overnight hours looks to increase winds speeds
across the region. A weak 7000mb cool front looks to impact the
region this afternoon ahead of the approaching upper-level trough,
leading to enough forcing to get showers and storms going across
much of the area. The Storm Prediction Center has highlight central
Nebraska in a Marginal Risk (Level 1 of 5) for severe weather this
afternoon, but this Marginal Risk does not quite clip Cheyenne
County, so the CWA is not under a risk from SPC at this time.
Temperatures should be warmer today than seen in previous days ahead
of the 700mb cold front, with highs in the mid-70s to mid-80s east
of the Laramie Range and low- to mid-70s west of the Laramie Range.
CAPE is expected to be quite low this afternoon, though a few
pockets of 100 to 300 Joules cannot be ruled out, especially across
the Panhandle. Severe impacts, however, will be limited once more by
the fog and low stratus over the Panhandle. Later this afternoon, a
surface high over northwestern Colorado and surface low over
northeastern Colorado will lead to a brief period of stronger winds
in between these two features, including much of Carbon, Albany, and
Laramie counties. Winds could gust up to 30 mph from background
winds alone.

Saturday will feature the upper-level trough moving through the
region and ushering in cooler air to the region. Highs on Saturday
will be decently cooler than Friday, in the upper-60s to mid-70s
across the region. A ridge will build in behind this trough, leading
to the beginning of the warming and drying pattern expected beyond
Saturday. Multiple 500mb vorticity maxima will eject across the
region Saturday, increasing precipitation chances once more. Severe
weather is not expected at this time, however, with residual
monsoonal moisture in the region, excessive rainfall remains a
threat once more.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 300 PM MDT Thu Aug 28 2025

Northwest flow continues through Saturday continuing our
chances for afternoon and evening. Sunday, the upper level ridge
starts to build back over the intermountain west. This will
slowly start to decrease the moisture over the region. A weak
disturbance does give us a slight chance for an isolated shower
but the probability looks low enough to not include in the
grids. Monday and Tuesday looks to keep us dry as the ridge
shift back over the Intermountain west as a low pressure system
enters the Pacific Northwest. Cluster analysis does show some
uncertainty as to the timing of the Low pressure system which
may break down the ridge by Tuesday afternoon but NBM looks to
side more with the GEFS and paints a 20 percent chance of
showers. However, if the Ridge doesn`t break down until Tuesday
evening as 70 percent of the Grand Ensemble members (GEFS, Euro,
Canadian GEPS) then we should stay dry until Wednesday.
Wednesday, The Intermountain West becomes sandwiched between an
upper level ridge and Low pressure system near the Great Lakes
Region. This will give us gusty winds for the rest of the week
and afternoon precipitation chances until at least the end of
the work week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 511 AM MDT Fri Aug 29 2025

Fog and low stratus ongoing across portions of western Nebraska
this morning with KBFF down with a quarter mile visibility and
an obscured sky. Conditions should begin to improve over the
next 1 to 2 hours at KBFF and KAIA, where IFR ceilings remain in
place. Gusty winds expected this afternoon as scattered showers
and storms develop once again. Clouds move back in tonight,
though look to remain VFR at this time.

&&

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

&&

$$

SHORT TERM...AM
LONG TERM...MM
AVIATION...AM