Slater, Wyoming Weather Forecast Discussion

939
FXUS65 KCYS 292117
AFDCYS
Area Forecast Discussion
National Weather Service Cheyenne WY
317 PM MDT Mon Sep 29 2025
.KEY MESSAGES...
- Scattered showers and thunderstorms will continue across the
  area through Monday evening. Another round is possible Tuesday
  PM.
- Expect warm, dry, and occasionally breezy conditions to
  prevail Wednesday through Friday.
- A pattern change to cooler and more unsettled weather is
  increasingly likely for the weekend.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 315 PM MDT Mon Sep 29 2025
A slow moving shortwave is moving from south to north across the
area this afternoon, helping to kick off another round of scattered
showers and thunderstorms. Mesoanalysis indicates that we have
excellent moisture over most of the area, exceeding the
climatological 90th percentile. Fairly high instability for the time
of year is also present, with SBCAPE between 500 and 1000 J/kg.
Vertical wind shear is rather unimpressive though, as light
southerly to southwesterly winds are present for most of the
vertical profile of the atmosphere. Today`s thunderstorm activity is
somewhat pulsey as a result, but could briefly produce small hail
and gusty winds in addition to locally heavy rainfall. This activity
is expected to continue through the evening hours, but should be
slow moving and mainly confined to southeast Wyoming. Some showers
and storms may creep into far western Nebraska during the
evening hours before dissipating. Clearing skies overnight
should allow for temperatures to drop slightly cooler than they
did this morning, with the exception of the typical breezy areas
and the Pine Ridge where southerly winds should keep
temperatures mild.
Look for a sunny start to Tuesday with temperatures warming
back to 5-10F above average for this time of year. The synoptic
pattern will be largely unchanged with a broad ridge dominating
the central and eastern CONUS, while a potent trough sits over
the Pacific Northwest. Another shortwave trough will eject to
the east Tuesday, moving across the area during the evening
hours. This should help kick off a few isolated showers and
perhaps a thunderstorm during the afternoon and evening.
Forecast soundings indicate a drier overall atmospheric profile
tomorrow, with a decent stable layer around 500-mb which may
lead to fairly low-topped convection. If showers manage to
develop, we may see some gusty winds with the highest chance
generally over Laramie County. Skies will trend clear again
towards Wednesday morning as the latest shortwave trough moves
out of the area.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 315 PM MDT Mon Sep 29 2025
An amplified ridge will be in place Wednesday and
Thursday with a predominant southwest flow bringing in mostly dry
air to the Intermountain west. Friday, we start to see a pattern
change as an upper level low pushes from the Pacific Northwest.
Precipitation chances start to increase during the day as a
shortwave ejecting from the low reaches the intermountain west. This
low will also be a driving factor for how the weekend will shape up.
The global models diverge on how to handle this upper level low for
this weekend. The GFS is more progressive with this system and the
Euro and Canadian seem to slightly stall the system a little bit
longer resulting in a more southern track and slower track when
compared to the GFS. This makes the timing of precipitation a little
more difficult but each model has precipitation occurring Saturday
and Sunday. Temperature is going to be another variable that will
change based on the timing of the system. A quick northern system
results in a little bit warmer temperatures because the arctic air
pulled down with the system wouldn`t have time to travel as far
south as with a slower southern system anticipated by the Euro and
Canadian. At the 700mb level temperatures range from -2 to 6 with
the warmer values over the Nebraska Panhandle and the lower values
over the Western Wyoming Teton mountain ranges. Any southeastern
progression could drop our temperatures from the forecasted 50`s and
60`s into the 30`s and 40`s if that colder air gets pushed further
east. This is a signal that will be watched carefully as we
could be seeing snow shortly into the month of October.
&&
.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1125 AM MDT Mon Sep 29 2025
Another round of scattered showers and thunderstorms is
anticipated this afternoon and evening. The highest chance for
impacts is at KLAR and KCYS, but a few reaching KRWL or KBFF
cannot be ruled out. Periods of gusty southerly winds are on
track again in the Nebraska panhandle this afternoon, which may
continue overnight at KCDR. Expect a clearing trend overnight
into Tuesday morning.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...MN
LONG TERM...MM
AVIATION...MN

NWS CYS Office Area Forecast Discussion