905
FXUS65 KCYS 240934
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
334 AM MDT Fri Jul 24 2026

.KEY MESSAGES...

- Hot temperatures will return to the area today and continue
  into early next week, producing near record highs Saturday
  through Monday.

- Widely scattered high-based showers and thunderstorms will be
  possible over the weekend. The primary hazard will be gusty
  winds.

- Another surge of monsoon moisture will arrive Monday,
  increasing rainfall chances for the early part of the work
  week.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 330 AM MDT Fri Jul 24 2026

The monsoon is beginning its break today as mostly clear skies
filter in across the area. While dry air is pushing in aloft, low
level moisture remains plentiful, which is producing some fog and
low cloud cover over western Nebraska this morning. Expect this to
clear out by mid morning as winds turn westerly from west to east
across the area today. On the synoptic scale, the upper level
ridge will amplify over the Four Corners region beginning today,
sending temperatures soaring over the next few days once again.
The warming will occur aloft first, with 500-mb temperatures
expected to exceed climatological maximums by this afternoon
while 700-mb temperatures remain "only" around the 90th
percentile. Forecast soundings show an inversion around 550-mb
this afternoon, that should limit convective instability.
However, models are showing this feature as considerably weaker
compared to 24-hours ago. So, while today`s convection activity
should still be limited, we may be able to get a few isolated
high-based showers or storms going, mainly over Carbon, Albany,
and Laramie counties.

The heat ramps up further on Saturday. 700-mb temperatures will
surge up to +17 to +20C Saturday afternoon per the NAEFS mean,
easily above the climatological 90th percentile and close to the
99th. This will edge up slightly further for Sunday. Saturday`s
highs will be within a few degrees of daily record highs at most
locations, ranging from the lower 90s in the Rawlins to Laramie
corridor, to the mid 90s around Cheyenne, and 100s for the remainder
of the High Plains below 5500 ft in elevation. Sunday`s highs look
to be 1-3 degrees warmer than Saturday, which will put numerous
daily record highs in jeopardy. Scottsbluff and Torrington have a
50/50 chance to exceed 105 degrees, while Chadron`s probability is
around 80%. Chadron even has approximately a 10% chance to exceed
110 on Sunday. With high temperatures expected to be around the
climatological 99th percentile Saturday through Monday, decided to
issue a long duration Heat Advisory beginning midday Saturday and
continuing through Monday evening. Saturday and Monday are fairly
marginal for local advisory criteria, but Sunday should exceed
criteria easily. In addition to the warm daytime temperatures,
overnight lows will be quite warm for our area. On Saturday night,
models show a modest nocturnal low-level jet developing, keeping
breezy southerly winds going overnight in the Nebraska panhandle.
Downsloping from the Pine ridge in Sioux and Dawes counties may keep
temperatures from dropping below the mid to upper 70s Saturday
night. If winds stay blowing through the morning, it is not out of
the question for Chadron to challenge it`s all time warmest minimum
temperatures of 82 degrees. As a result of the warm overnight
temperatures, northern Sioux and Dawes counties will be approaching
criteria for an Extreme Heat Warning. Confidence was too low to
issue this product currently, but an upgrade of the existing Heat
Advisory could be needed if confidence improves later.

While the main story this weekend will be the heat, we will also
have elevated to near critical fire weather conditions returning to
portions of the area. The airmass will not be really all that dry,
even in the lower levels, but the exceptionally hot temperatures
will manage to push RH to near critical values anyway. Confidence in
the winds being consistent enough to warrant Red Flag Warnings is
low at this time, but we will need to watch this over the next few
days. As the low-levels warm this weekend, we will actually see a
very slight cooling aloft. The result will be steeper lapse rates
and a bit more instability Saturday and Sunday. Moisture aloft will
also remain fairly decent through this heat wave, though this will
be on top of deep inverted-v boundary layers. Expect to see widely
scattered high-based showers and isolated thunderstorms developing
during the afternoon on Saturday and Sunday. These won`t be dry in a
strict sense, but the probability for wetting rainfall is pretty
low. Still, this activity will have the potential to produce dry
(ish) microbursts, and potentially severe (>58 mph) wind gusts. The
NBM is not really picking up on any storm potential whatsoever, so
PoPs were manually increased above this to include the mention of a
slight chance for showers/storms in the official forecast. This also
looks like an excellent set up for heat bursts both Saturday and
Sunday evenings.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Issued at 330 AM MDT Fri Jul 24 2026

Monday will be another hot day across the area, though daily highs
should be 1-3 degrees cooler than Sunday. The persistent, powerful
ridge aloft will shift slightly eastward of its weekend position
over the Four Corners, opening up the tap for another surge of
monsoon moisture into our area. NAEFS mean precipitable water climbs
back to the climatological 90th percentile by late Monday and
remains there through at least Wednesday. A shortwave trough will
also push through late in the day on Monday, enhancing lift across
the area. As a result, we can expect to see an increase in shower
and thunderstorm coverage on Monday, Tuesday, and possibly
Wednesday. In addition, we will see an increase in the potential for
these storms to produce appreciable rainfall beyond just gusty
winds. Temperatures are expected to remain warm (particularly
overnight), but we will be closer to seasonal averages Tuesday
onwards compared to the weekend heatwave.

Ensembles show a gradual decrease in precipitable water Thursday
onward as the upper level ridge very slowly retrogrades back to the
west. Towards the end of the forecast period, the ridge position is
in a much more unfavorable position for potent monsoon surges like
we saw over the last few days, but ample recycled moisture (and
perhaps stronger forcing than a typical monsoon surge) should keep
daily chances for scattered showers and thunderstorms in the
forecast.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1118 PM MDT Thu Jul 23 2026

Lingering moisture overnight will provide CDR, BFF, and AIA with
approximately a 30% chance for fog and low clouds between 10z
and 14z Friday morning. Confidence was too low to add IFR as a
prevailing group, but this was hinted at with mild VIS drops and
SCT lower cloud layers.

Otherwise, VFR conditions will prevail through the TAF period
resulting in dry and tranquil conditions as high pressure builds
across the Rocky Mountain West. Other than any convective
debris from decaying showers and thunderstorms from earlier this
evening, expect just a few high clouds aoa 20k ft. Winds are
expected to remain light and variable below 10 knots.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Heat Advisory from 11 AM Saturday to 9 PM MDT Monday for
     WYZ101-102-107-108-118-119.
NE...Heat Advisory from 11 AM Saturday to 9 PM MDT Monday for
     NEZ002-003-019>021-054-055-095-096.

&&

$$

SHORT TERM...MN
LONG TERM...MN
AVIATION...NB