869
FXUS65 KCYS 312126
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
326 PM MDT Thu Jul 31 2025

.KEY MESSAGES...

- Scattered to widespread thunderstorms continue through the
  beginning of the weekend with a daily risk of strong to severe
  weather possible.

- Isolated to scattered showers and storms through the weekend, then
  decreasing precip potential through midweek.

- Gradually increasing temperatures over the course of the
  period alongside an increasing risk of fire weather concerns.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 300 PM MDT Thu Jul 31 2025

Scattered showers and thunderstorms already increasing in
coverage across the high terrain of Carbon and Albany Counties
this afternoon and moving slowly eastwards into a more favorable
environment for convective development. Current mesoanalysis
indicates PWAT values of over an inch starting near the NE border
and eastwards, alongside MLCAPE values of 1000-2500 J/kg in
eastern WY, and 0-3km shear values maxing at 30-35 knots. All of
this is contributing to supercell composite values of 8-12 for
southeastern WY and the western extent of the NE Panhandle. High
res guidance is honing in on some clusters of activity through
this evening, and with a severe thunderstorm watch about to be
issued it does look likely that we will see at least a couple to
few warnings through the evening. Most likely culprits with this
would be clustered storms with near to severe hail and some
strong wind gusts, and with the high PWAT values for this time
of year another round of flooding concerns can`t be ruled out as
well.

Moving into the overnight period, storms should start to weaken
with the setting of the sun and the loss of daytime heating,
though lingering showers could be possible through the evening
and early nighttime hours. Southerly to southeasterly upslope
flow should once again promote low clouds and possibly some fog,
but with moisture moving slowly eastwards Cheyenne may be just
west of this area. And on that note, another round of afternoon
convection is then possible on Friday as the axis shifts just
slightly eastwards. Much like today, storm initiation and
strength will be dependent on cloud cover and and how it lingers
as this could limit or inhibit development. But with a similar
setup to today, more clusters of activity could bring hail and
winds once again. Further west however, moisture will start to
depart Carbon and Albany Counties. Teens to near single digit
afternoon RH values are expected, and with breezy winds into the
20-30 mph range possible we may be encroaching onto critical
fire weather concerns. For now have held off on a watch or
warning, but don`t be surprised if we begin a series of red flag
days that will extend into the long term forecast period.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Issued at 300 PM MDT Thu Jul 31 2025

The mid-/upper-level flow will be characterized by ridging over the
High Plains and Intermountain West. PoPs will largely be governed by
the placement of an expansive moisture axis extending from Texas to
the Dakotas. PoPs look to transition from isolated/scattered
coverage on Saturday and Sunday (mainly in the afternoons and
evenings) to isolated at most (~10% chance) mainly across the
eastern half or so of the County Warning Area (CWA) on Monday,
Tuesday, and Wednesday. Subsequent forecast packages may shift PoPs
slightly farther west or east, depending on how global models -- and
hi-res models, once we are within their time windows -- position the
moisture axis.

The Storm Prediction Center (SPC) currently has the southern portion
of our Nebraska Panhandle counties outlined in a Marginal Risk
(level 1 out of 5) for severe thunderstorms on Saturday. Decent
surface-to-500mb bulk shear embedded within the aforementioned ridge
could aid in intensification/organization of diurnally-driven
storms. PWATs associated with the moisture axis over the CWA are not
progged to be anomalously high, so widespread flash flooding is
unlikely. Additionally, speed maxima around 25-35 kts along the
periphery of ridge (and over much of the CWA) should keep storms
moving at a decent clip, again precluding flooding potential in any
one area.

Heat is expected to gradually build through the long term period
given the aforementioned drying trend and ridging aloft. On Tuesday
and Wednesday, high temperatures in the mid-90s to upper 90s are
forecast across the Plains, with upper 80s to lower 90s across the
higher terrain of Albany County and Carbon County.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1143 AM MDT Thu Jul 31 2025

Expecting another chance at thunderstorms today with all sites
possibly seeing activity nearby to at the terminals. Any storms
that happen through this evening could be strong to severe and
include erratic and gusty winds as well as hail and heavy
rainfall. If storms do occur at TAF sites, they will reduce
visibilities to MVFR or below status. Any lingering MVFR CIGs in
the Nebraska panhandle this afternoon should lift to just
above, around 5k feet. Prevailing wind fields will be breezy
with gusts around 20-30 knots. Winds should lessen overnight and
cloud decks remain moderate to high, though expecting another
round of lower ceilings into the morning hours for the Nebraska
Panhandle terminals. For now, keeping this out of KCYS as
probabilities are much lower here and moisture should shift a
bit further east, but if it does occur don`t be surprised.

&&

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

&&

$$

SHORT TERM...CG
LONG TERM...KM
AVIATION...CG