829
FXUS65 KCYS 280753
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
153 AM MDT Mon Sep 28 2026

.KEY MESSAGES...

- Unsettled weather returns to the area today, with chances for
  showers and thunderstorms this evening through at least
  Tuesday.

- A cooling trend begins Monday with near or slightly below
  average temperatures expected mid-week. Another warming trend
  will resume for the end of the week.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 152 AM MDT Mon Sep 28 2026

Upper-level troughing will continue across the western CONUS to
start the week. A fetch of southwesterly flow aloft originating
in the Pacific Ocean at the base of the upper-leve trough, will
continue to funnel moisture into the region. Per the NAEFS Mean
Precipitable Water, precipitable water values will remain at
and above the 90th percentile through the first half of the
week, favoring continued rain chances across the CWA. Down at
700mb, the CWA will be sandwiched between the trough off to the
west and the ridge across the Central Plains into western
portions of the Midwest. As a result, 700mb height gradients
will increase, leading to a low-level jet around 40kts across
the western Nebraska Panhandle throughout the day today. This
low-level jet will shift easterly during the afternoon hours
today as the ridge starts to move further to the east. 700mb
temperatures will peak in the 6 to 9C range this afternoon,
leading to surface temperatures in the mid-60s to low- 80s. A
weak 700mb cold front will move through overnight tonight into
early Tuesday morning, dropping 700mb temperatures into the 4 to
6C range overnight and back into the 6 to 8C in the afternoon.
Temperatures on Tuesday will be cooler, thanks to this front,
with highs in the low-60s to low-70s everywhere. Precipitation
chances return Tuesday afternoon, though probability of
precipitation remains fairly low, around 30 to 50%.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 152 AM MDT Mon Sep 28 2026

No major changes, please see previous discussion...

Tuesday night through the end of the work week could see a few areas
of showers trying to lift up into the region, but this remains
largely uncertain and low confidence as models remain split on the
evolution of low pressure to our south and how far north moisture
can make it. While some ensembles have begun to push the low and
moisture associated with what will be the remnants of Hurricane Polo
further northwards compared to the last few runs, overall this
system still looks to be too far south to bring any further
appreciable moisture to our area beyond Tuesday outside of maybe our
farthest southeast zones, primarily Cheyenne County in the Nebraska
Panhandle. The NBM continues to keep us high dry as well, with the
above scenario remaining in the grids as of this writing. Still
through Thursday POP chances aren`t completely zero, but outside of
the I-80 corridor and southward it`s not looking favorable for any
meaningful moisture in the long term. Otherwise we`ll see a very
slight warming trend on Wednesday, with temperatures warming a few
degrees with widespread 60`s and a few 70`s expected, but a second
cold airmass should drop us right back down into the widespread 60`s
on Thursday. Friday and Saturday high pressure over the southwestern
US will allow for a warming and drying trend, returning us to
several degrees above normal with highs in the 70`s across the
region. Sunday flow turns more northwesterly and a glancing upper
level trough will help push a weak cold front into the region,
bringing temperatures back down to near normal, but a lack of
notable moisture will keep our precipitation chances almost nil and
provide little more than a brief cool down to end the long term
forecast.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1122 PM MDT Sun Sep 27 2026

A tricky forecast for this period as showers and storms will lift
across the region through the overnight hours and again by Monday
afternoon, with chances for all terminals. Any storms could bring
locally lowered VIS along with gusty and erratic winds. CIGs will
generally be mid-level as precipitation moves in, but will lower
tonight into Monday morning as an influx of moisture overspreads the
region. Low CIGs and VIS continues to plague KCDR, conditions should
improve through the nighttime hours as winds increase from the
south, look for AMDs in the TAF.

&&

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

&&

$$

SHORT TERM...AM
LONG TERM...AM/CG
AVIATION...RZ