004
FXUS65 KCYS 061755
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1155 AM MDT Mon Oct 6 2025

.KEY MESSAGES...

- Freeze Warning is in effect for portions of Carbon, Albany,
  and Converse Counties from midnight tonight to 9am Tuesday.

- Cloudy day expected Monday with clouds slowly clearing early
  Tuesday morning.

- Warmer, drier conditions return mid-week.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 207 AM MDT Mon Oct 6 2025

Cold and wet out there tonight with showers continuing to develop
and move northeastern from Cheyenne towards Alliance and Chadron. On
and off showers should continue through the overnight hours as
easterly and southeasterly flow keep upslope ongoing. Temperatures
have dropped well into the mid-30s to mid-40s across the entire
area. The I-80 Summit is socked in with fog this morning after snow
showers finally moved off and became rain further downstream. Low
clouds are present everywhere, leading to a fairly cold and dreary
night with welcomed precipitation.

The upper-level trough will slowly drag across the region today,
leading to most cloudy skies, continued precipitation chances, and
much cooler temperatures. Cloudy skies are expected to remain
overhead throughout the day today, with most locations likely not
seeing the sun until sunrise Tuesday. Precipitation chances will
slowly taper off throughout the day today as the upper-level trough
responsible for the cold, cloudy, and wet conditions moves off to
the east. Behind this trough, an upper-level ridge is building and
slowly moving eastward. This ridge should impact the region Tuesday,
leading to clearing skies, dry conditions, and warmer temperatures.
700mb temperatures are expected to increase into the 3 to 5C range
by late Tuesday, leading to daytime highs in the 50s and 60s, much
warmer than the 40s and 50s expected Monday.

However, before temperatures can increase across the region, another
cool night is expected. The ridge will act to clear skies Monday
night into Tuesday morning, leading to enhanced radiational cooling
overnight. As a result, temperatures are expected to plummet into the
20s and 30s west of the Laramie Range and 30s east of the Laramie
Range. With light winds overnight, portions of Carbon County,
Converse County, and Albany County will see temperatures dropping
into the 25 to 32F range. As a result, upgraded the Freeze Watch to
a Freeze Warning for those areas. The Freeze Watch is in effect from
midnight tonight through 9am Tuesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 319 PM MDT Sun Oct 5 2025

A ridge starts to build into the Intermountain West
Tuesday into Wednesday. This ridge will increase 700mb temperatures
into the 5 to 7C range which will translate our high temperatures
raising into the 60`s and 70`s. There is a weak shortwave that
pushes through the Intermountain West however it looks like the
stronger vorticity stream will just be to north of the Southeast
Wyoming area. So our region looks to stay dry Wednesday. The ridge
strengthens behind the weak shortwave so Thursday and Friday will
remain in the 60`s and 70`s. Overnight temperatures look to remain
in the 30`s and 40`s for the long term period a clear signal that
winter will be here soon. Another trough pushes into the
Intermountain West from the Pacific Northwest this weekend. This
looks to increase the rain chances starting Saturday afternoon and
lasting through the weekend. 700mb temperatures range from 3 to 10c
giving us warmer temperatures into the overnight period (40`s/50`s)
and potentially some 80 degree days into the Nebraska Panhandle.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1155 AM MDT Mon Oct 6 2025

A weak upper level disturbance will slide across the CWA today with
conditions slowly improving for all terminals throughout the
afternoon generally from north to south. In the meantime, the main
cloud deck is pretty locked in for a majority of the terminals,
especially those east of I-25. MVFR CIGs are holding firm for KCYS,
KLAR, KBFF, KCDR, KSNY, and KAIA. Based on the latest VIS satellite
imagery, clouds appear to have broken up pretty nicely for KRWL.
Overall, expect CIGs to lift and conditions to improve for all
terminals by 01Z and throughout the remainder of the TAF
period. KCYS may see a return of lower CIGs late tonight with
improvement in the morning hours, by about 15Z.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Freeze Warning from midnight tonight to 9 AM MDT Tuesday for
     WYZ101-104-110-111.
NE...None.

&&

$$

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