131
FXUS65 KCYS 031155
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
555 AM MDT Wed Sep 3 2025

.KEY MESSAGES...

- Drier conditions expected through much of this week with warm
  temperatures continuing through Thursday.

- Cooler temperatures and more unsettled Friday through next
  weekend as a Canadian cold front and a Pacific cold front
  impact the region.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 250 AM MDT Wed Sep 3 2025

All models continue to show dry and benign weather for most of
the region as an upper level high over Idaho, western Wyoming
and the Four Corners region remains over the area. Backdoor cold
front across far northern Wyoming and South Dakota is forecast
to gradually move south across the high plains today and this
evening, eventually stalling along the Laramie Range tonight.
Winds will increase slightly out of the north or northeast
behind the front with gusts of 20 to 30 mph possible this
afternoon. Thankfully, the bulk of the unseasonably cool airmass
will remain far to the east across the northern plains and the
Great Lakes region over the next few days. For our area, the
eastern plains will get a glancing blow with high temperatures
around 10 degrees lower compared to Tuesday afternoon for areas
east of the I-25 corridor. Generally expect temperatures near or
slightly above normal along and west of the I-25 corridor, and
around 5 degrees below normal for far eastern Wyoming and
western Nebraska. Regardless, it should be pleasant day with
intervals of clouds expected along the front. Can`t rule out a
few rain showers or sprinkles along and north of the North
Platte River valley, but confidence is limited...so kept out of
the forecast for now.

For Thursday, with increasing cloud cover, do not expect
Thursday morning lows to be as bad as previous guidance was
suggesting, so increased lows closer to normal and generally in
the mid 40s to mid 50s. However, if it clears out more than
expected, so places may drop into the low 40s and even upper 30s
by early Thursday. All models show another warm day as the
upper level ridge axis remains nearby. Afternoon temperatures
will recover with highs in the upper 70s and upper 80s Thursday
afternoon with another day of dry weather.

&&

.LONG TERM /FRIDAY THROUGH NEXT TUESDAY NIGHT/...
Issued at 300 AM MDT Wed Sep 3 2025

Long range models continue to struggle with run to run
consistency this weekend and early next week in regards to the
Pacific energy pushing onshore and across the Rocky Mountains.
Current models show the upper level energy more fragmented and
less organized compared to yesterday. In addition, models have
trended much further south with the tropical moisture plume
associated with the forecast track of Tropical Storm Lorena,
currently near the southern tip of Baja California. However,
still expect showers and thunderstorms to develop late Saturday
and mostly on Sunday with cooler temperatures continuing through
this weekend...especially further south along the I-80
corridor. Sunday looks like the most favorable day for scattered
to numerous showers and thunderstorms as a weak Pacific
disturbance slowly moves east across the area. Kept POP between
40 to 60 percent over mostly southeast Wyoming, with POP lower
than 30 percent across western Nebraska. Friday still looks like
the coolest of the next 7 days and pretty fall-like with highs
in the mid 60s to low 70s behind the main cold front.

For next week, models in better agreement showing a rebound of
the upper level ridge axis...this time closer to the Front Range
and the Rocky Mountain region. Further west, all models indicate
a stronger storm system moving onshore along northern Calif and
Oregon...which will be the next system to watch as we head into
later next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 555 AM MDT Wed Sep 3 2025

Upper level high pressure over Utah and western Wyoming will
dominate the weather over the next few days. A dry backdoor cold
front will move over the eastern plains this morning resulting in
intervals of clouds and gusty northerly winds, mainly for the
eastern plains terminals.

HAZARDS/WEATHER TRENDS: VFR conditions expected to continue through
Wednesday evening. Winds will shift into the north after sunrise and
occasionally gust up to 20 to 25 knots at times for all terminals
except for KRWL. A period of low MVFR CIGS around 1000 to 1500 feet
AGL is expected with the frontal passage at KCDR between 13z
and 18z this morning...with a lower probability (~10%) at KAIA.

&&

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

&&

$$

SHORT TERM...TJT
LONG TERM...TJT/CG
AVIATION...TJT