367
FXUS65 KCYS 012351
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
545 PM MDT Thu Oct 1 2026

.KEY MESSAGES...

- Near perfect and dry early Autumnal weather will prevail into
  early next week.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 204 PM MDT Thu Oct 1 2026

Tonight...Primary challenge will be fog duration, areal coverage and
cessation. Northwest flow aloft prevails. With return southerly flow
at low levels, the low level jet kicks in, especially across the
Nebraska Panhandle. Boundary layer progs suggest areas of low clouds
and some fog will likely develop along and east of Interstate 25,
roughly, and perhaps over the Southern Laramie Range. Thus, agree
with the Denver/Boulder NWS office and have added areas of fog along
and near the I-25 corridor overnight. Low clouds may be more
prevalent as occurred this morning. Where low level mixing will be
maximized, decent low level winds will keep minimum temperatures
locally higher, such as near Wheatland and over Sioux and Dawes
Counties near the Pine Ridge.

Friday...A picture perfect day for outdoor weather enthusiasts due
to a minimum of cloud cover, mild southerly winds and 700 mb
temperatures near 11 Celsius yielding maximum temperatures from the
mid 70s to mid 80s. As a persistence forecast, expect areas of low
clouds and some fog to dissipate by late morning, as has occurred
this morning. No precipitation expected due to the limited low and
mid level moisture, and paucity of cloud cover.

Friday night/Saturday...In this early autumnal progressive synoptic
pattern, the next shortwave trough aloft moves into eastern Montana,
aiding in the development of a leeside surface trough east of the
Rockies from western South Dakota to northeast New Mexico. This
decent mixing and atmospheric column warming will produce a
relatively mild overnight for early October with relatively mild
lows in the lower to mid 50s from Douglas to Wheatland to Scottsbluff.

On Saturday, the shortwave ridge aloft moves to the eastern Dakotas,
with a weak cold front, dry due to the lack of enough low and mid
level moisture, sweeping south of our forecast area, and bringing in
a shot of cooler Canadian origin air, dropping maximum temperatures
to the lower 70s to lower 80s, perfect for outdoor weather
activities.

Saturday night...In the cooler airmass behind the cold front, expect
cooler overnight low temperatures compared to Friday night,
although it appears there will be residual cloud cover, perhaps
scattered, to limit cooling.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Issued at 204 PM MDT Thu Oct 1 2026

Mostly benign and warm conditions expected as we move into the
long term starting with Sunday, which will actually be our
coolest day of the period. We`ll see widespread temperatures in
the 70`s with a few sites possibly peaking around 80, but Monday
into Tuesday more widespread upper 70`s to 80`s will be present
under high pressure ridging. This feature may briefly recede
and flatten thanks to troughing to the north and allow for a bit
more widespread 70`s to return by the end of the forecast
period, but this will likely be brief as extended models show
the ridge building back in beyond the long term. Otherwise with
no major features expected to add variability to the forecast,
pressure gradients will remain on the weak side with a chance
at daily breezy, diurnally driven winds, but nowhere near strong
for this region. Elevated to near critical fire weather
conditions could be present thanks to the expected dryness and
the afternoon breezy winds, and will need to be monitored
particularly on Monday when RH`s look to be at their lowest.
Overall there is high confidence in the forecast, with ensembles
showing near unanimous agreement on the above forecast, as a
warm start to fall and October continues.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 545 PM MDT Thu Oct 1 2026

Northwest flow aloft will become westerly and more zonal for Friday
through this weekend with breezy conditions after sunrise and dry
conditions.

HAZARDS/WEATHER TRENDS: VFR conditions will prevail over the next 24
hours. Will continue to keep an eye on the fog and low CIGS
potential at KCYS and KSNY, but confidence remains on the low side
(15% to 25%). Added FEW-SCT low clouds for now at these terminals.
Otherwise, breezy south to southeast winds will continue for the
western Nebraska terminals and KCYS through Friday, with winds
shifting into the west for KRWL and KLAR after 15z Friday with gusts
up to 30 knots.

&&

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

&&

$$

SHORT TERM...RUBIN
LONG TERM...CG
AVIATION...TJT