612
FXUS65 KCYS 112336
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
536 PM MDT Tue Aug 11 2026

.KEY MESSAGES...

-Red Flag Warning through 9 PM tonight for much of southeast
 Wyoming for gusty winds, low humidities and dry lightning from
 some storms.

-Marginal risk of severe thunderstorms east of a Lusk to
 Cheyenne line Wednesday afternoon and evening, with a slight
 risk of severe thunderstorms for much of the Nebraska
 Panhandle.

-Cooler with widespread showers and scattered thunderstorms for
 Thursday, producing beneficial rainfall.

-Decent chances for afternoon and evening showers and
 thunderstorms Friday through the weekend, with high
 temperatures only in the upper 70s to mid 80s, providing a
 respite from the hot weather.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 103 PM MDT Tue Aug 11 2026

Tonight...Challenges include ongoing Red Flag Warning along with
shower and thunderstorm coverage and gusty winds from convection.

The ongoing Red Flag Warning is looking decent, especially across
Converse County where winds and relative humidities are exceeding
Red Flag Warning criteria. The main threats from isolated to
scattered thunderstorms from the Snowy Range across the Laramie
Valley to the southern Panhandle will be high based thunderstorms
producing dry lightning and therefore necessitating the need for the
Red Flag Warning continuing until 9 PM.

As far as shower and thunderstorm coverage, models including the
HRRR and NAM suggest scattered showers and isolated thunderstorms
through early evening from Saratoga, to Laramie, to Cheyenne, to
Kimball and to Sidney and nearby locations. Due to the dry low
levels and steep dry adiabatic lapse rates, most of the rain from
storms will evaporate or fall as virga, and produce brief, erratic
and gusty winds in the stronger storms up to 55 mph.

There is a minimal threat for an isolated strong to severe
thunderstorm up in the northern Nebraska Panhandle through early
evening along a surface convergence boundary and decent 850/700 mb
theta-e ridge axis. CAPE and shear look adequate for a few storms to
become strong to severe, most likely in Dawes County Nebraska, our
infamous Dawes County Clipper.

Wednesday and Wednesday night...The Storm Prediction Center in
Norman, Oklahoma paints a marginal risk of severe thunderstorms in
the afternoon and evening roughly east of a Lusk to Cheyenne line,
with a slight risk of severe thunderstorms for most of the Nebraska
Panhandle. This seems quite plausible considering the following
factors. A pronounced shortwave trough aloft, markedly noticed in
the 700 mb flow near 10,000 feet MSL, will pass across our counties
near peak heating and during the early evening hours, while an
impressive low level convergence axis develops along the Wyoming and
Nebraska state line in the afternoon. Low level moisture will be
plentiful across western Nebraska with dewpoints in the 60s with a
healthy 850/700 mb theta-e ridge axis oriented north to south across
western Nebraska.

CAPE values from 1000 to 2500 J/kg and bulk shear values near 35
knots for the Nebraska Panhandle will be sufficient for scattered
thunderstorms, some severe in the afternoon and evening, and have
painted large hail and damaging winds in the slight risk area in the
grids, with small hail and gusty winds for the marginal risk area
east of a Lusk to Cheyenne line.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 103 PM MDT Tue Aug 11 2026

Thursday evening starts off this long term period with
monsoonal moisture moving in, and a shortwave moving through the
area. With precipitable water values in the 1-1.5 range, RH
values 60-90%, and the shortwave, its safe to say our area will
be getting some much needed moisture. This moisture sticks
around through Monday, bringing daily afternoon chances of
precipitation. This precipitation looks to mainly be showers,
but an isolated thunderstorm cannot be ruled out especially near
the NE panhandle with CAPE values near 1000J/kg. Winds do not
appear to be out of the ordinary, staying below 15 knots most of
the time. Temperatures cool off as a cold front moves over the
area Thursday. 700mb temperatures stay near 12C during the
daytime Thursday-Sunday, with nighttime temperatures getting
near 10C. This means temperatures will cool off nearly 20F from
what we have been experiencing. Typically our area has daytime
temperatures near 83F this time of year. This is a welcomed
break from our hot temperatures the last few weeks. With all of
this monsoonal moisture coming in, fire weather is not a concern
through this long term period.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 532 PM MDT Tue Aug 11 2026

Gusty winds are possible in the WY terminals through 06Z. WY
terminals have mostly westerly to northwesterly winds. NE
terminals can expect to see more variance in the winds, but most
terminals will see a shift from easterly to southeasterly.
Winds stay below 12 knots for most terminals in the area through
this TAF period. VFR conditions are expected through this TAF
period.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 9 PM MDT this evening for WYZ417>430.
NE...None.

&&

$$

SHORT TERM...RUBIN
LONG TERM...ML
AVIATION...ML