931
FXUS65 KCYS 172332
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
532 PM MDT Fri Jul 17 2026

.KEY MESSAGES...

- Hot, dry, and breezy conditions continue through Sunday before
  a much awaited cold front arrives for the start of the week.

- Monday looks to be the last 100+ day for the upcoming week or
  so, with reduced fire concerns also arriving with cooler
  weather.

- Monsoonal moisture will attempt to return as early as Monday,
  leading to increased precipitation chances through much of
  next week.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 220 PM MDT Fri Jul 17 2026

The short term should remain fairly similar to the last several
days as high pressure ridging continues to sit over the region
with warm temperatures today in the upper 80`s to near triple
digits, increasing a few degrees with nearly widespread 90`s to
100`s across the area on Saturday. Because of this increase in
coverage of triple degree heat, a Heat Advisory was issued
beginning Saturday for portions of Sioux and Dawes counties,
with several more zones added in beginning on Sunday. We should
also continue to see elevated fire weather conditions as
surface relative humidity values sit in the 15-20% range while
breezy, diurnally driven winds of around 20-25 mph will be
present, but if any site is able to reach critical criteria for
fire weather conditions it`s not expected to persist for 3 or
more hours. Finally upslope flow today may once again fuel an
isolated shower or storm across our high elevation and
mountainous locations in Carbon and Albany Counties, but with
inverted V sounding profiles precipitation may struggle to reach
the ground under weaker cells, and instead we could see the
potential for a rogue dry lightning strike or gusty outflow
winds. Monsoonal moisture attempts to finally swing into the
region on Saturday, but guidance has dialed back or
precipitation chances with Carbon and Albany County once again
at an isolated to widely scattered probability of seeing some
development. Better moisture should return just beyond the short
term on Sunday and thereafter.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 220 PM MDT Fri Jul 17 2026

Sunday...GFS progs the ridge aloft over the northern Rockies to be
flattened somewhat with zonal flow developing over Montana and
northern Wyoming. A weak perturbation, or shortwave trough aloft,
will move across our counties in the afternoon and evening, with
monsoonal moisture advecting into our western counties west of I-25,
where we anticipate scattered showers and thunderstorms to develop
in the afternoon west of I-25, with the greatest areal coverage over
the Snowy, Sierra Madre and northern Laramie Ranges. So, more
beneficial rain will occur.

Monday...Monsoonal moisture at low and mid levels increases further,
aiding in another increase in late day shower and thunderstorm
coverage, and beneficial rains, with coverage increasing to
scattered 30 to 60 percent POPS, probability of measurable
precipitation, with the greatest coverage over and near our mountain
zones.

Tuesday-Friday...A relatively significant pattern change will occur,
with "beware" northwest flow aloft developing along with a decent
increase in low and mid level moisture and upslope southeast
mechanical lift at low levels, and occasional passing shortwave
troughs aloft, helping to produce scattered to numerous showers, and
scattered thunderstorms in the afternoons and evenings, with
beneficial rainfall and possibly some locally heavy rains from some
of the slower moving thunderstorms. The most likely locations for
locally heavy rain and the greatest areal coverage may be along and
east of Interstate 25. On Friday, the GFS progs the last of the
passing shortwave troughs aloft to move into Nebraska by evening,
with shortwave ridging aloft bulging across Wyoming, thus expect an
attendant decrease in areal afternoon and evening shower and
thunderstorm coverage.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 524 PM MDT Fri Jul 17 2026

Regional radars are clear this evening. Winds out of the south
to southeast between 10 to 15 knots. A stationary front in the
northern Nebraska Panhandle is expected to drift south and could
lower ceilings at KCDR and KAIA overnight. Very low chance of
fog at KCDR. Winds calm to become variable at most terminals
during the late overnight and early morning hours.

Tomorrow afternoon diurnal heating will create scattered cloud
coverage and increase winds out of the east to southeast at
10 to 15 knots. At KRWL enough shower and storm coverage is
present in hi resolution models to introduce a prob30 group
into the TAF. The stationary front could be a focal point for
some isolated to scattered showers and storms which could impact
KAIA. Chances are too low at this time to introduce a prob30.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Heat Advisory from noon Sunday to 6 PM MDT Monday for WYZ101-
     102-108.
NE...Heat Advisory from noon Saturday to 6 PM MDT Monday for NEZ002-
     095.
     Heat Advisory from noon Sunday to 6 PM MDT Monday for NEZ003-
     019>021-096.

&&

$$

SHORT TERM...CG
LONG TERM...RUBIN
AVIATION...RV