064
FXUS65 KCYS 292340
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
540 PM MDT Sun Jun 29 2025

.KEY MESSAGES...

- Strong to severe thunderstorms expected this afternoon and
  evening with a severe thunderstorm watch out.

- Elevated fire weather conditions continue for Carbon county

- Warm temperatures and daily coverage of isolated to scattered
  afternoon and evening showers and thunderstorms expected for
  Tuesday through Sunday.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 102 PM MDT Sun Jun 29 2025

Mesoscale analysis shows an environment prime for some strong to
severe thunderstorm development as of this writing, with CAPE
around 1000-2000 J/kg and bulk effective shear of 20-40 knots. A
severe thunderstorm watch is in effect through 9 PM tonight for
areas east of and around I-25 not including Converse County. The
environment is supportive of large hail and damaging wind gusts,
but wind may become the more predominant threat as storms shift
eastwards through the evening hours. High resolution guidance is
in pretty solid agreement on this timeframe, with clustered
storms departing the Nebraska Panhandle around 9-10 PM.

Overnight activity should wane though a few lingering showers
or weak storms may be possible for these areas through the
morning hours. Ceilings may also lower and some mist or weak
fog could be possible for areas including Cheyenne and Sydney,
though confidence is overall low in this. For Monday a few
upslope showers or storms may develop off of the high terrain in
Wyoming, but probabilities are overall on the low side and we`ll
see this quickly wane with the setting of the sun. Otherwise
today and tomorrow will be the coolest days of the period, with
highs today in the 70`s to 80`s with widespread highs on Monday
in the 70`s to low 80`s thanks to the cold front. That will
change as we move into the long term though as summer warmth
returns.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 102 PM MDT Sun Jun 29 2025

Tuesday...A warming trend develops as 700 mb temperatures rise to
near 15 Celsius. Adequate moisture aloft for isolated to widely
scattered late day showers and thunderstorms, mainly over and near
the mountains.

Wednesday...The warming trend continues as 700 mb temperatures reach
16 Celsius. Moisture availability looks less than Tuesday, thus we
anticipate less shower and thunderstorm coverage.

Thursday-July 4th...Similar temperatures on Thursday compared to
Wednesday with 700 mb temperatures near 16 Celsius. A bit cooler for
July 4th, with more cloud cover and moisture aloft. Scattered late
day showers and thunderstorms each day.

Saturday...Although ridging aloft builds overhead, there should
still be adequate low and mid level moisture for scattered afternoon
and evening showers and thunderstorms. Slightly cooler temperatures
expected for most locations.

Sunday...Slightly warmer as the flow aloft turns westerly. Adequate
low and mid level moisture for scattered late day showers and
thunderstorms, mainly east of Interstate 25.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 535 PM MDT Sun Jun 29 2025

Scattered thunderstorms are moving eastward this evening and
will have aviation impacts to most terminals. confidence is
highest in direct impacts at KBFF and KAIA, with PROB30 groups
elsewhere where confidence is not quite as high. Storms will be
capable of producing frequent lightning, strong, gusty, and
erratic winds, IFR VIS in heavy rainfall, and isolated large
hail. Strong thunderstorm activity should wind down by around
04z, but a few showers may linger in the NE panhandle well into
the night.

Moist, upslope flow in the lower levels will point towards some
low CIGs to begin Monday morning. Confidence is highest in KCYS,
but KLAR, KSNY, and KAIA may also see MVFR to IFR CIGs. This
should clear out mid to late morning, with a relatively quiet
day for Monday.

&&

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

&&

$$

SHORT TERM...CG
LONG TERM...RUBIN
AVIATION...MN