215
FXUS65 KCYS 232325
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
525 PM MDT Sun Aug 23 2026

.KEY MESSAGES...

- Lower coverage of showers and thunderstorms today, mainly
  further south near the Colorado border and western Nebraska.
  Brief strong gusty winds and locally heavy rainfall expected
  with this activity into this evening.

- Daily shower and thunderstorm chances continue Monday through
  the end of the week with slightly above average temperature
  expected until Thursday.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 252 PM MDT Sun Aug 23 2026

Another active afternoon and evening is forecast. Storms have
already begun to appear on radar early this afternoon, albeit not
many. Coverage of storms will likely be less than yesterday with
more dry air present from westerly winds aloft. A weak dryline is
also present on observations across the CWA, roughly running along
the Interstate 25 corridor. Behind the dryline remains fairly
quiet with just a few cumulus fields. Ahead of the dryline is
where storms currently are in Nebraska. The Nebraska panhandle
is also where the highest instability is, with mesoanalysis
suggesting more than 1500 J/kg of SBCAPE. Shear is decent, but
likely not enough to get very strong storms. A few isolated
severe storms are likely, with initial discrete cells posing a
hail risk. As afternoon progresses to evening, the threat will
switch to more of a wind one, with storm clusters entering the
far western portion of the CWA. The intensity of these storms
will be weaker than the ones in the Nebraska panhandle, but
severe wind gusts will still be possible due to DCAPE values in
excess of 1200 J/kg from the dry surface. Showers and storms
will continue through the evening hours with a few lingering
showers possible after midnight.

Rinse and repeat the same song and dance again for Monday. The
environment looks similar to Sunday but with better forcing
from an upper-level shortwave moving through the ridge. Coverage
and intensity of storms on Monday will likely depend largely on
where the weak dryline can set up. Some models push the dryline
far enough east out of the CWA where the more intense storms
will not impact the forecast area. Newer CAM guidance has begun
to recede the dryline further back into the Nebraska panhandle
which will likely result in storm development during the
afternoon hours. Initial discrete cells that develop will pose
more of hail threat, but will shift more towards a wind threat
as they cluster. Much like Sunday, showers and weaker storms
will enter the western portion of the CWA during the evening and
move eastward. Wind will be the primary concern with these
given the drier low-levels and high DCAPE values. Severe wind
gusts cannot be ruled out. Showers will linger through the
overnight hours.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 252 PM MDT Sun Aug 23 2026

No major changes to the overall long term forecast as we see
conditions slightly warmer than average to start the period and
then by the end of the week into next weekend we warm back up to
several degrees above average with monsoonal moisture providing
a daily chance of thunderstorms with a low end severe risk
generally expected each day. At the upper levels, a strong ridge
of high pressure will control the Western US, and should
continue to hold control until the end of the week when a deep
low will approach the western Canadian coastline. This feature
may begin to move inland and could interrupt our pattern by late
next weekend, but until then expect largely similar conditions
each day. Moisture at the surface may begin to slowly dwindle,
and by the late week into the weekend elevated fire weather
concerns may begin to arise as minimum daytime RH values drop
back into the teens. Still, daily PWAT values will sit around
120-130% of normal, and between daytime instability and weak
disturbances riding the periphery of the ridge, we should still
see thunderstorm chances each afternoon with a low end severe
threat possible. At the surface meanwhile, a cold front will
stall out on Tuesday and then begin advancing back eastwards as
a warm front but should become very slow moving to even
stationary, helping to fuel storm initiation through the end of
the week. Overall it will be more of the same as we remain in a
fairly stagnant pattern through the period.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 525 PM MDT Sun Aug 23 2026

VFR conditions will prevail across all terminals for the
duration of this TAF period. An exception may be where a shower
and/or thunderstorm comes near or over a site, primarily KAIA
and KSNY, reducing CIGs and VIS briefly. If this happens, look
for an AMD TAF. Generally breezy conditions with winds 10-20
knots for the remainder of the day for the southeast Wyoming
terminals. Winds will weaken overnight through tomorrow morning
to 10 kts or less. Then ramp back up after 18Z Sunday with gusts
back up to around 20 knots.

&&

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

&&

$$

SHORT TERM...SF
LONG TERM...CG
AVIATION...RZ