861
FXUS65 KCYS 100039
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
639 PM MDT Wed Jul 9 2025

.KEY MESSAGES...

- A Red Flag Warning is in effect for portions of Carbon County
  through Wednesday evening due to very dry conditions alongside
  breezy winds.

- There is a potential for isolated strong to severe storms on
  Thursday afternoon and evening for portions of the western
  Nebraska panhandle.

- Much cooler Thursday night and Friday as a strong cold front
  moves south across the high plains.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 329 PM MDT Wed Jul 9 2025

Tonight through Thursday, The upper level ridge starts to shift east
and flatten overnight. This will allow a weak shortwave to traverse
across the Intermountain west. The Rap model puts between 200-400
joules as this shortwave progresses eastward. Thats enough
energy to have some showers and weak thunderstorms. SPC shares
the same idea as General thunder is shown over Carbon County and
the WY/NE border. There is a marginal risk for the eastern
portion of the Panhandle but that seems to be mostly from storm
development in South Dakota that dives south and hits Sioux and
Dawes county. Water Vapor does show a little bit of a plume of
moisture centered on Sioux and Dawes but its uncertain if the
dry line will develop anything in our area.

For Thursday, NAEFS has the Integrated Vapor Transport (IVT) in the
90th percentile advecting in from the west. Main forcing for
tomorrow`s severe threat will be a shortwave that is preceded
by a strong cold front in the late evening into overnight
period. Model soundings have roughly 1000-1500 sbcape with
500-600 Joules of MLCAPE. As time progresses the better moisture
still looks to be in the Panhandle however even with Mid-level
lapse rates between 8-9C the shear looks to be between 20 to 30
knots meaning the area may see some pulsy messy storms into the
late evening. The western portion may see some storm development
as that cooler air from the front increases instability but its
uncertain the magnitude of storms produced. Soundings show that
classic inverted V sounding for tomorrow over Rawlins and
Laramie. With that dry airmass near the surface its uncertain if
precipitation will reach the ground if storms do develop or
potentially have a dry lightning situation in an area with near
critical to critical fuels. Model consensus does show the threat
ending by midnight or 06z for our area. The other side of this
cold front is that morning temperatures look to be a little bit
cooler by as much as 10 degrees with temperatures starting out
in the 50`s.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 329 PM MDT Wed Jul 9 2025

A potent upper level trough stretching from the US/CAN border
southwest through to the Rockies on Friday will push a cold front
south through the forecast area. Temps will be 5-10deg cooler behind
the front with gusty north-northwest winds. Moisture through the
column will increase as well bringing overcast skies and potential
for showers and thunderstorms through the afternoon. Focus for
initiation will be along the eastern slopes of the terrain in the
frontal upslope regime. Coverage as this activity moves eastward
will depend on the timing of the upper level support with the
associated trough. Kept mainly chance probabilities for most of the
area with higher probs (60 percent range) over the terrain through
the evening. Stratus/fog are likely in the post frontal airmass for
most of the forecast area Friday night. Saturday will see northwest
flow aloft with embedded weak disturbances in the flow. Showers and
storms will likely focus along the Laramie Range where best wind and
moisture convergence prevails in the low levels. Temps will warm
back into upper 80s to mid 90s on Sunday with chances for showers
and storms confined to the mountains once again.

Models are still showing another potent upper low over southern
Canada dropping another strong cold front across the forecast area
on Monday. Timing of the front at this time looks to be in the
afternoon, so high temps will remain hot and thunderstorm chances
and intensity will depend on the midlevel cap. Expect cooler
temperatures in the post frontal environment for Tuesday along with
upslope stratus/fog in the early morning. Upslope forcing along with
cooler midlevel temps will keep chances for showers and
thunderstorms in place through Tuesday evening.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 558 PM MDT Wed Jul 9 2025

Gusty winds will be the main forecast concern through the early
overnight period at most sites. Wind direction will be west to
southwest across southeast WY through this time, where locations
western NE will see westerly winds switch to the east to
southeast by 03Z. Still expecting showers with gusty and
erratic winds moving in to KRWL and KLAR from the west after
midnight. Another round of showers and thunderstorms is
expected across the area Thursday as a frontal boundary moves
south across the area from late morning through the afternoon.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 10 PM MDT this evening for WYZ420>423-
     425-427.
NE...None.

&&

$$

SHORT TERM...MM
LONG TERM...RM
AVIATION...RM