236
FXUS65 KCYS 090941
AFDCYS
Area Forecast Discussion
National Weather Service Cheyenne WY
341 AM MDT Wed Jul 9 2025
.KEY MESSAGES...
- A Red Flag Warning is in effect for portions of Carbon County
through Wednesday evening due to very dry conditions alongside
breezy winds.
- There is a Slight Risk for severe weather Thursday for
portions of the western Nebraska panhandle.
- Much cooler Thursday night and Friday as a strong cold front
moves south across the high plains.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 330 AM MDT Wed Jul 9 2025
Quiet and clear early this morning with dry conditions and
relatively mild temperatures at 3:00 am. Radar shows one lone
thunderstorm over northern Nebraska at this hour as it moves
southeast away from the forecast area. Upper level ridge axis
will remain over the region today with another hot day
expected. 700mb temperatures expected to climb between 17c and
20c this afternoon, which will translate to highs in the 90s at
the surface, even over the high valleys of Albany and Carbon
counties. Further east, high temperatures will likely reach the
century mark in several locations, especially for Goshen, Scotts
Bluff, Dawes, and Box Butte Counties. A few record highs might
be tied or broken, with Laramie having the best chance to set a
new record (92 forecast high versus 93 record). Mostly dry
today as midlevel subsidence associated with the upper level
ridge will be dominant. Models do show a weak shortwave digging
southeast across the western Dakotas this afternoon, with high
res CAMs showing isolated strong thunderstorms over western
South Dakota and northern Nebraska. This activity will likely be
close enough to Dawes, Sioux, and Box Butte counties this
afternoon, so added isolated thunderstorms to the forecast in
these areas. With MLCAPE around 1000 j/kg and inverted V
sounding near Chadron, sudden strong gusty winds are the most
likely concern today...but activity will be very isolated.
For Tonight and Thursday, models show the gradual breakdown of
the upper level ridge as it ridge axis quickly moves eastward
into the Great Plains early Thursday morning. This will allow
a progressive upper level Pacific shortwave to push into Wyoming
through the day. Showers and embedded thunderstorms may develop
before sunrise Thursday west of I-25. There is some concern for
dry lightning in this area due the recent dry conditions and
low surface humidities, but not confident enough to headline
this dry lightning concern in the fire weather forecast at this
time. Slight cooler temperatures for Thursday afternoon but
highs will still be in the 80s and low 90s for most locations,
warmest over western Nebraska. As the trough axis and midlevel
cooler air moves over the area, instability will increase along
with marginal 0-6km shear around 25 knots. Forecast soundings
show SBCAPE between 2000 to 3000 j/kg across the eastern high
plains in the afternoon. With the increased forcing ahead of the
trough and marginal shear values, linear growth looks likely
with afternoon and evening thunderstorms on Thursday with strong
gusty winds possible and some threat of large hail.
Thunderstorm activity will linger through the evening hours as
the trough axis pushes east of the Nebraska/Wyoming border, but
should end before midnight.
Once the shortwave trough axis moves east of the area, models
show the upper level flow veering into the northwest for
Friday as a relatively strong cold front for this time of year
digs south into the Front Range. Expect much cooler temperatures
for Friday and the potential for overcast skies for much of the
day and even some fog along the Laramie Range as surface winds
shift into the east. Models are not in very good agreement with
precipitation chances as some models (NAM, previous GFS,
Canadian) show a low stratus deck...cooler temperatures...and
limited thunderstorm development. Other models (ECMWF, current
00z GFS) show widespread showers and scattered thunderstorms
developing along a convergence axis near the spine of the
mountains. Expect this area across southeast Wyoming and far
southwestern Nebraska to have the best chance of seeing decent
rainfall amounts in the afternoon and evening hours. The threat
of strong to severe thunderstorms may shift further west into
Carbon, Albany and western Platte/Laramie counties this time
around with a lower chance of widespread stratus. Kept POP
around 60 percent for these areas. Highs in the 70s to near 80
are expected, which is still around 10 degrees below average for
mid July.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY NIGHT/...
Issued at 340 AM MDT Wed Jul 9 2025
For this weekend, a gradual warming trend is expected as the
upper level high across the desert southwest slowly builds
northward and intensifies. Thunderstorm activity is forecast to
become more isolated through Sunday as 700mb climb above 15c.
Highs in the upper 80s to mid 90s will return for much of the
forecast area by Sunday and next Monday.
Further out, models are indicating another pretty strong cold
front for mid July dipping southward out of Canada by late
Monday and into the middle part of next week. Models show 700mb
temperatures below 0c as a broad upper level trough digs south
into Montana and the northern Great Plains. Another sudden cool
down is possible next week; however, ensemble spreads are
relatively high which indicates higher than average
uncertainty for days 6 and 7. Lowered max and min temperatures a
bit, but kept them above some of the latest guidance. It is a
favorable pattern for showers and thunderstorms, so kept POP and
prob thunder close to the recent NBM.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1016 PM MDT Tue Jul 8 2025
Ridging aloft will produce dry and hot weather through the TAF
period. Skies will be mostly clear. Winds will gust to 25 knots
at the Wyoming terminals from 15Z to 01Z.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 10 PM MDT this evening for WYZ420>423-
425-427.
NE...None.
&&
$$
SHORT TERM...TJT
LONG TERM...TJT
AVIATION...RUBIN
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