147
FXUS65 KCYS 160347 CCA
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
945 PM MDT Wed Jul 15 2026

.KEY MESSAGES...

- Hot, dry and breezy conditions expected through the end of the
  week.

- Mostly dry weather will continue for Friday and Saturday,
  with daily increasing chances for afternoon and evening
  showers and thunderstorms for Sunday through Wednesday due to
  monsoonal moisture spreading eastward across southeast Wyoming
  and western Nebraska.

- Maximum temperatures will remain hot Friday and Saturday,
  with a decent cooling trend in high temperatures for Sunday
  into midweek due to increasing cloud cover and increasing
  shower and thunderstorm coverage.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 140 PM MDT Wed Jul 15 2026

Short term remains much of the same as a ridge of high pressure
aloft continues to sit over the region with a very weak surface
front associated with a trough moving into the CWA through
Thursday night. As this weak boundary makes its way into our
area, some high resolution guidance is trying to form some
initiation off of it and bring a chance for thunderstorms, but
with incredibly dry surface profiles producing inverted V
soundings and daytime dewpoints in the 40`s, more than likely if
anything can form off of this boundary it`s going to be high
based with virga struggling to reach the surface as rain, and
threatening only dry lightning or a gusty outflow. But aside
from a couple of the high resolution models, struggling to see
much in the way of meaningful or even weak precipitation being
possible, and so have left the NBM as is with no additions to
precipitation chances at this time. Otherwise this front isn`t
going to offer much in the way of relief as temperatures are
nearly identical to today with highs in the upper 80`s to upper
90`s, with perhaps a degree or two shaved off west of the I-25
corridor, but otherwise relief not in sight from this summer
heatwave. As for headlines, pressure gradients will weaken
enough that winds should lessen into Thursday and RH values will
at least rise into the upper teens to low 20`s, enough that Red
Flag conditions will be allowed to expire today. Heat advisory
for Thursday also feels unnecessary with only a site or two
expected to reach triple digits, and so will let those expire
this evening, but a new heat advisory may be needed for the
weekend when temperatures rise once again.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 140 PM MDT Wed Jul 15 2026

Friday...Ridging aloft remains entrenched over our region, while
there should be a slight increase in mid level monsoonal moisture,
though likely not enough mid level moisture to initiate thunderstorm
development, because of the warm mid level 700 mb temperatures from
15 to 20 Celsius, producing enough CIN, Convective Inhibition, to
keep POPS near nil. Near perfect day weatherwise for outdoor weather
activities, with maximum temperatures in the mid to upper 80s west
of I-25, and 90s to near 100 degrees east of I-25. Please be sure to
drink plenty of water and stay hydrated when outdoors for any
significant length of time.

Saturday...With the ridge aloft remaining parked over Wyoming, and
warm mid level temperatures producing enough CIN, convective
inhibition, this will limit areal coverage to isolated to widely
scattered showers and thunderstorms over our Snowy and Sierra Madre
Ranges in the afternoon, and over much of Carbon County including
Rawlins in the evening...otherwise dry.

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. Monsoonal moisture is progged to advect
further eastward in the evening, spawning isolated to scattered
showers and thunderstorms for our counties east of I-25, with lesser
coverage over the Nebraska Panhandle.

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, with the greatest coverage over
and near our mountain zones.

Tuesday and Wednesday...The zonal flow aloft continues with abundant
monsoonal moisture remaining over our CWA, County Warning Area,
helping to produce scattered to numerous showers and scattered
thunderstorms in the afternoons and evenings with more beneficial
rainfall, again with the highest areal coverage over our Snowy,
Sierra Madre and Laramie Ranges.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 945 PM MDT Wed Jul 15 2026

Upper level high pressure is expected to slightly weaken today
before rebuilding for the weekend. Expect increasing clouds and some
shower and thunderstorm activity to return to Carbon and Albany
counties, but coverage is uncertain at this time.

HAZARDS/WEATHER TRENDS: VFR conditions expected with southeast winds
continuing over the next 24 hours. Gusty southeast winds will
continue tonight for KCDR and maybe KAIA as the low level jet
restrengthens. Surface pressure gradient doesn`t look quite as
strong for Thursday, so kept gusts generally below 20 to 25 knots
between 17z Thursday and 02z Friday.

&&

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

&&

$$

SHORT TERM...CG
LONG TERM...RUBIN
AVIATION...TJT