633
FXUS65 KCYS 111730
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1130 AM MDT Mon Aug 11 2025

.KEY MESSAGES...

- Dry weather expected with a warming trend for Tuesday and
  Wednesday. A slow cooling trend for Thursday through Sunday
  with isolated to widely scattered late day showers and
  thunderstorms.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 123 PM MDT Sun Aug 10 2025

Hi-Res guidance continues to struggle, with most models completely
missing the convection that was present most of the morning across
western Nebraska and far eastern Wyoming. However, it is not
surprising that storms did develop this morning as an upper-level
trough axis moves into the CWA, providing the necessary lift on top
of minor instability, relatively steep lapse rates, and elevated dew
points. Despite the poor performance of models this morning,
CAMs have consistently been showing more showers and storms
developing this afternoon as the trough axis traverses the CWA.
With cooler, more stable air in place today, the severe threat
will be somewhat limited. Model soundings from the GFS still
show MUCAPE values below 1200 J/kg which suggests stronger
storms, but perhaps not severe storms. Main concern with storms
today will be the potential for severe hail. Even storms early
this morning appeared to have a hail signature. Cannot rule out
some gusty winds in storms, but even DCAPE values are rather
unimpressive for the high plains. Hi-Res guidance shows storm
initiation over the high terrain by mid-afternoon, pushing into
eastern Wyoming and western Nebraska by late afternoon/evening
timeframe. Storms will continue, mainly in the southern Nebraska
panhandle, through the evening hours. As previously mentioned,
widespread severe storms are not likely this afternoon, but
cannot rule out a few isolated strong to marginally severe
storms. Once storms clear out, the rest of the overnight will be
quiet.

Heading into the start of the work week, the trough over the center
of the country will weaken, allowing a ridge of high pressure to
build over the west coast. This ridge will usher warmer and drier
air into the CWA on Monday. High temperatures will be about 5
degrees warmer than today, with most locations expected to be in the
80s. Weak subsidence will keep skies mostly clear throughout most of
the day, with minimal chances for precipitation.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 123 PM MDT Sun Aug 10 2025

Tuesday...The warming trend continues as heights aloft and
thicknesses increase. 700 mb temperatures near 14 Celsius will yield
high temperatures in the 80s. Continued dry with minimal low and mid
level moisture.

Wednesday...With 700 mb temperatures rising to near 19 Celsius,
maximum temperatures will rise to the upper 80s to near 100 degrees.
Continued dry with lack of low and mid level moisture and warm
temperatures aloft.

Thursday...Continued hot as 700 mb temperatures remain about the
same. With a slight influx of low and mid level moisture, and a
passing shortwave trough aloft, we expect to see isolated to widely
scattered afternoon and evening thunderstorms.

Friday...Slightly cooler as 700 mb temperatures drop a little.
Enough low and mid level moisture for widely to scattered late day
showers and thunderstorms.

Saturday...With weak disturbances in the flow aloft, and adequate
low and mid level moisture, we anticipate widely to scattered
afternoon and evening thunderstorms once again. Slightly cooler with
more cloud cover.

Sunday...With slightly less atmospheric moisture, we expect a small
decrease in late day shower and thunderstorm coverage. Maximum
temperatures close to those of Saturday.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1128 AM MDT Mon Aug 11 2025

VFR conditions expected for the forecast period. Modest
northerly wind gusts to around 20 knots are expected at WY
terminals today. Winds may be variable at times at all terminals
overnight into Tuesday morning.

&&

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

&&

$$

SHORT TERM...SF
LONG TERM...RUBIN
AVIATION...MN