796
FXUS65 KCYS 011142
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
540 AM MDT Mon Sep 1 2025

.KEY MESSAGES...

- Drier conditions expected through much of this week with a
  warming trend bringing near normal temperatures.

- A few showers and thunderstorms possible Wednesday and Friday
  afternoon.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 225 AM MDT Mon Sep 1 2025

Current surface observations across the area early this morning
and 10.3-3.9 fog product shows some patchy fog across the
Nebraska panhandle from Alliance southward to areas northeast of
Sidney. Alliance is the only location reporting fog with
visibilities briefly down to 1/2 mile. Expect these low clouds
and fog to spread a bit further north and west across the
panhandle before sunrise. Added fog to the forecast from Dawes
county southward towards Morrill and Cheyenne county. Fog should
lift around 7 to 8 am.

All models continue to show dry and benign weather for most of
the region as an upper level high forms near the Four Corners
region today. This upper level high is forecast to drift
northward into Utah and the eastern Great Basin region by
Tuesday. Although mid to upper level flow will remain light out
of the north or northwest, a slow warming trend will continue
for Wyoming and western Nebraska. Highs will return to the upper
70s to mid 80s early this week...warmest across the lower
elevations of far eastern Wyoming and western Nebraska. Dry
conditions will remain for most of the area today and Tuesday.
However, GEFS and ENS ensembles have trended higher with POP
across southeast Wyoming with the 00z ECMWF showing a pretty
good chance of thunderstorms across the mountains and the
adjacent plains/high valleys. low to midlevel analysis does show
an area of notable low level convergence with east winds across
the high plains, but north to northwest winds west of the I-25
corridor. Added 15 to 20 percent POP west of I-25 into Laramie
and Platte counties Tuesday afternoon. Surface moisture will be
lacking with dewpoints likely in the 30s.

For Wednesday, models have continued to show the major early
fall cold front only clipping the forecast area as the bulk of
the colder air moves into the northern/central plains and the
Great Lakes region by midweek. Still expect a slight cool down
for our area with highs only a few degrees below average and
generally in the 70s. Surface cold front will push across the
area in the afternoon, so can`t completely rule out a few
showers or embedded thunderstorms Wednesday afternoon and
evening. Activity should be very isolated with limited moisture
and instability.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Issued at 250 AM MDT Mon Sep 1 2025

Rather quiet for the long term as most models show the stubborn
upper level ridge remaining near the forecast area. Still expect
Thursday morning to start feeling like early autumn with
widespread lows in the to mid 40s for southeastern Wyoming and
western Nebraska behind Wednesday`s cold front. With the upper
level ridge axis nearby, afternoon temperatures will recover
with highs in the 70s and low 80s Thursday afternoon.
Precipitation chances appear limited due to the dry airmass and
limited instability, but the best chance for showers and an
isolated thunderstorm will be Friday afternoon as the upper
level ridge begins to break down. Cooler temperatures are also
expected Friday as another weak cool front digs south out of
Canada.

For next weekend, models continue to hint to the gradual break
down of the western upper level ridge as the eastern Pacific
becomes a little more active. Will continue to keep an eye on
this to see how it evolves, but ensemble spreads remain pretty
high next weekend with precipitation and temperatures. Ensembles
and deterministic models have trended higher with measurable
precipitation through early next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 540 AM MDT Mon Sep 1 2025

Upper level ridge axis across western Wyoming and Colorado will
dominate the weather pattern over the next day or two. This will
result in dry conditions and somewhat breezy northerly winds.

HAZARDS/WEATHER TRENDS: VFR conditions will continue for most
terminals Monday with north to northeast winds gusting to around 20
knots by midday. LIFR conditions in fog will continue for KAIA until
15z until the low stratus deck lifts after sunrise. Brief IFR CIGS
may sneak into KCDR between 12z and 14z, but impacts should be
brief. Otherwise, VFR conditions at all western Nebraska terminals
after 15z.

&&

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

&&

$$

SHORT TERM...TJT
LONG TERM...TJT/RZ
AVIATION...TJT