449
FXUS65 KCYS 291809
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1209 PM MDT Sun Jun 29 2025

.KEY MESSAGES...

- Scattered showers and thunderstorms expected Sunday. A few
  storms will have the potential to become strong to severe.

- 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
  Monday through Saturday.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 150 PM MDT Sat Jun 28 2025

Cumulus field beginning to setup across the CWA with a few
echoes noted just east to southeast of Laramie County, with
activity in Colorado already producing a few strikes of
lightning. Lapse rates remain steep on environmental analysis,
but noteworthy instability is limited to just the Nebraska
Panhandle with 500 J/kg or less for Wyoming border and westward,
and shear is near non-existant. Heating and mixing should
continue to contribute to development through this evening, with
high based thunderstorms expected (surface moisture remains
abysmal, with most RH values in the 20`s to teens and dewpoints
struggling to make it past 50 degrees). High resolution guidance
is indicating we`ll see our initial rounds developing over the
next few hours and spread eastwards, particularly across
Niobrara and Goshen Counties in Wyoming and the northern half of
the Nebraska Panhandle, but the NAM Nest is also pinging
additional development spreading into these areas beginning
again this evening and into the nighttime hours and re-igniting
another round of stronger to severe storms. Regardless, any
storms that do form will have the potential for hail and strong
wind gusts, and activity even along and west of the I-25
corridor can`t rule out stronger wind gusts due to the inverted
V soundings thanks to the dry conditions at the surface. On the
note of dry conditions, breezy winds and low relative humidities
are continuing to fuel the ongoing Red Flag Warning for Carbon
County, continuing into this evening before winds lessen and RH
values rise back above critical thresholds.

Moisture should overspread the region on Sunday and, alongside
the slowly propagating backdoor cold front, should bring more
temperate conditions as highs drop back down into the 70`s to
80`s, alongside a more widespread shower and thunderstorm risk
for the day. High resolution models are much more excited for
areas in Laramie County for the day, with the HREF paintball for
reflectivity 40 dBZ or greater coloring in almost the entire
county. While overall instability will be a bit lower for the
day compared to Saturday, soundings show a favorable profile for
hail development, so expect the potential for strong winds and
large hail, encompassing from the Laramie Range eastwards.
Further west though, another round of dry surface conditions
with RH values into the teens and breezy winds could bring
another round of enhanced fire weather conditions. On the fence
currently if we`ll see 3 hours of critical conditions though,
and will coordinate with the evening shift to determine if
smaller red flag warning may be needed tomorrow or not.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 150 PM MDT Sat Jun 28 2025

Monday...Temperatures about the same as on Sunday, with low level
upslope east winds and 700 mb temperatures near 10 Celsius. Despite
adequate low and mid level moisture, we should see a decrease in
coverage of showers and thunderstorms due to ridging aloft.

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 east of I-25.

Wednesday...The warming trend continues as 700 mb temperatures reach
16 Celsius. Moisture looks similar to Tuesday, thus we anticipate
isolated late day showers and thunderstorms.

Thursday-July 4th...Similar temperatures to Wednesday with 700 mb
temperatures near 16 Celsius. Adequate low and mid level moisture
again, thus isolated to scattered late day showers and thunderstorms
expected. Looks like decent weather for outdoor holiday activities.

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.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1151 AM MDT Sun Jun 29 2025

VFR conditions will be prevalent over the next 24 hours, with a
handful of exceptions. First, showers and thunderstorms are
expected to develop this afternoon and impact all sites through
this evening, and any storms could produce locally heavy
rainfall and reduce visibilities for brief periods, alongside
gusty and erratic winds. Storms could even be strong to severe
from KCYS through the Nebraska terminals, with very strong winds
and hail possible. Then, cloud bases will remain generally mid
level at around 3-6k feet, but later tonight a lowered cloud
deck could bring reduced CIGs below 1-2k feet for KCYS and KSNY.
Otherwise expect clouds decks outside of this to lift, becoming
mid to high level and clearing into tomorrow. Winds will be
breezy through this afternoon, around 10-20 knots with gusts
20-30 knots possible outside of the aforementioned storms,
weakening into tomorrow morning.

&&

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

&&

$$

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