560
FXUS65 KCYS 020931
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
331 AM MDT Wed Jul 2 2025

.KEY MESSAGES...

- Warm temperatures and daily chances for PM showers and
  thunderstorms will continue late this week and into the
  weekend.

- Seasonably warm on July 4th with a chance of afternoon showers
  and thunderstorms earlier in the day.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 308 AM MDT Wed Jul 2 2025

Not many changes to the previous forecast package as all models
continue to show a typical summer weather pattern setting up
across the western United States extending eastward into the
Front Range and Rocky Mountain Region. For today, models
show the developing ridge axis strengthening and extending
northward out of Texas into southern Wyoming. 700mb temperatures
will respond with values between 14c to 18c across eastern
Wyoming and western Nebraska. These temperatures will translate
to surface highs in the upper 80s to mid 90s across a bulk of
the forecast area. This ridge axis is expected to drift eastward
slowly, which should suppress deep convection across the eastern
plains for much of the day. There is also no noticeable forcing
today, so expect single cell thunderstorms across the higher
terrain of southeast Wyoming this afternoon through this
evening. A few runs of the HRRR wanted to initiate near the
Nebraska border today, but have since backed off as of 06z. This
makes sense after looking at current model soundings with a dry
and stable layer around 500mb. Kept any mention of
thunderstorms/showers mainly along and west of Interstate 25,
and even this may be a little too far east given current model
trends. Gusty winds are possible with this activity (including
shower activity).

For Thursday, models continue to trend wetter with a higher
coverage of thunderstorms...at least across southeast Wyoming.
Models show a broad eastern Pacific trough moving into the
Great Basin Region and finally into the Rocky Mountain area
Thursday afternoon. This feature is expected to advect some
subtropical moisture ahead of the trough as PWATs increase
between 1.00 to 1.50 inches. A quick look at NAEFS shows PWAT
and specific humidity between the 90th and 95th percentile
across mainly southeast Wyoming but also extending east into
western Nebraska late in the day. Can`t rule out some heavy
persistent rain showers with this feature. WPC continues to
indicate a marginal risk for excessive rainfall along and west
of the I-25 corridor. Kept POP between 40 to 60 percent through
the evening hours.

Slightly cooler temperatures for Friday as the upper level
trough lifts northeast across the area and brings some cooler
air and increased cloud cover over the region. High temperatures
will still be near normal for this time of the year and
generally in the 80s. Showers and thunderstorms may actually
occur earlier in the day as the trough axis moves east of the
region by midday. This may result in mild and pleasant weather
for the late evening hours of July 4th.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY NIGHT/...
Issued at 330 AM MDT Wed Jul 2 2025

Somewhat drier conditions on Saturday as models show a shortwave
ridge axis building over Colorado and Wyoming behind the upper
level trough. This will be short-lived as most synoptic models
show a back door cold front moving southwest across the high
plains with ample surface convergence and moisture along the
mountains.

For next week, we will continue to monitor the development of a
strong 595 to 600dm upper level high developing near the four
corners region/eastern Great Basin. At this time, most models
and ensembles have trended further southwest with this upper
level high...developing closer to Nevada with northwest flow
aloft across southeast Wyoming. Kept temperatures close to
average for now with a daily chance of thunderstorms in the
forecast. Will need to watch this pattern closely since it can
be a pattern conducive for severe weather across the high plains
as we head into the middle of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1140 PM MDT Tue Jul 1 2025

Shower and thunderstorm activity has ended for the night with skies
becoming mostly clear through early Wednesday morning. Upper level
ridge axis will build over the area Wednesday resulting in less
coverage of showers and thunderstorms Wednesday afternoon into
Wednesday evening.

HAZARDS/WEATHER TRENDS: VFR conditions will prevail over the next 24
hours. Another round of showers and possible thunderstorms are
forecast for Wednesday afternoon, but should mainly impact KRWL and
KLAR. Further east, can`t rule out some shower activity and an
embedded thunderstorm, but confidence is too low to include for KCYS
and the western Nebraska terminals.

&&

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

&&

$$

SHORT TERM...TJT
LONG TERM...TJT
AVIATION...TJT