549
FXUS65 KCYS 051104
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
504 AM MDT Sun Oct 5 2025

.KEY MESSAGES...

- Gusty winds up to around 55 mph are ongoing along I-80 near
  Arlington/Elk Mountain and the I-80 Summit and will continue
  through the  overnight hours.

- Breezy conditions return for much of the CWA this afternoon as
  a secondary, reinforcing cold front moves through.

- Upper-level ridging returns for the start of the work week,
  leading to warmer temperatures by mid-week.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 222 AM MDT Sun Oct 5 2025

Low stratus has begun to move into western and northern portions of
the region with some areas in the Panhandle see light, patchy fog
this morning. Winds are very gusty tonight with the Arlington/Elk
Mountain wind-prone area gusting 55mph at this time, with many other
45 to 55 mph gusts along the I-80 corridor. A Special Weather
Statement was issued for the Arlington and the I-80 Summit zones
until 12Z this morning. Wind gusts are not expected to be sustained
long enough to prompt the need for a High Wind Warning. In
Cheyenne, gusts to around 30 to 35 mph have been observed overnight
tonight. Most shower activity has exited the area as of 08Z this
morning. Precipitation chances return later today.

Another wet day expected for the CWA as the upper-level trough
slowly migrates eastward, leading to ample synoptic lift across the
region this afternoon as the jet remains in a favorable location
aloft. Multiple 500mb vorticity lobes will move across the region
throughout the day, further supporting synoptic lift, especially
across western portions of the region. Much cooler temperatures for
today as 700mb temperatures remain around the -1 to +1C range today
and a secondary, reinforcing shot of cold air pushes through the
region. As the secondary cold front pushes through, surface winds
turn northerly and remain fairly elevated for locations east of the
Laramie Range. With synoptic ascent favored across the region and
the secondary cold front pushing through, precipitation chances will
continue through the day, picking up around 00Z this evening.
Precipitation chances become more widespread through the afternoon
and evening hours. An embedded thunderstorm or two cannot be
completely ruled out, but no severe weather is expected today. Winds
will remain elevated through the day, first with a stronger 700mb
jet currently ongoing and secondly with the reinforcing cold front
pushing into the region and tightening pressure gradients as the
surface. Therefore, a breezy, cool, and rainy day is expected for
much of the region today, with mostly cloudy skies.

Overnight tonight into Monday, cloudy skies will remain overhead as
the upper-level trough keeps clouds in the area and cooler
temperatures. There is a chance that locations in far southwestern
Carbon County may see temperatures approaching 32F. However, clouds
overhead should act to keep the surface warmer overnight, leading to
temperatures likely in the 33 to 35F range. As a result of this, did
not issue any Freeze headlines for this zone. Better conditions
exist Monday into Tuesday for a potential Freeze across many of the
remaining Wyoming zones that have not seen Freeze headlines this
year. 700mb temperatures remain in the -1 to +1C range Monday night
into Tuesday, but clouds will begin to clear as the upper-level
trough finally moves through the area and an upper-level ridge
building over the western CONUS starts to impact the region. With
clearing skies and cooler overnight temperatures, Freeze potential
increases significantly for Monday night into Tuesday. Will hold off
for now on issuing any Freeze headlines as the event is still a few
days away and confidence will improve.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 247 PM MDT Sat Oct 4 2025

Monday, the upper level trough starts to exit the
Intermountain West and enter the Northern Plains. The cooler air
behind the trough looks to stay for a couple of days with 700mb
temperatures between -1 and -3C. This will keep our high
temperatures for Monday and Tuesday into the 50`s and 60`s. 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.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 501 AM MDT Sun Oct 5 2025

Another complex forecast this morning for the 12Z TAFs as rain
showers will be present across much of southeast Wyoming
throughout the day and ceilings begin to fall as winds turn
easterly in the evening. VFR conditions expected to prevail
until 22Z, with KRWL seeing MVFR to IFR ceilings by 16Z this
morning. Winds turn easterly at all terminals by 22Z, with rain
showers becoming more concentrated along the Laramie Range near
KLAR and KCYS. Once easterly flow sets in, lowering ceilings are
expected through the night, with the Wyoming terminals seeing
IFR ceilings and the Nebraska terminals seeing MVFR ceilings.
Fog may develop along with the easterly flow for locations east
of the Laramie Range. Confidence in fog is low at this time, but
cannot completely be ruled out.

&&

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

&&

$$

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