297
FXUS65 KCYS 142041
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
241 PM MDT Mon Sep 14 2026

.KEY MESSAGES...

- Critical fire weather conditions expected today alongside the
  potential for high winds.

- Much cooler on Tuesday with temperatures a few degrees warmer
  through the end of next week and daily chances of showers and
  thunderstorms.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 239 PM MDT Mon Sep 14 2026

The upper level low is slowly lifting northeast from Montana and
into the Canadian Providence of Saskatchewan. The attending cold
front that brought the light showers and low cloud deck over the
Nebraska Panhandle is moving eastward into Central Nebraska putting
cooler but dry subsident air over the Intermountain West. The
showers currently over the Rocky mountains in Colorado are expected
to continue to move North-Northeast to East-Northeast into eastern
Laramie county to Cheyenne county, Nebraska to give this area some
possible light rain chances this evening and into the overnight
period. However the dry slot may end up destroying and dissipating
any weak shower as it crosses into our area. Pops were lowered from
the NBM to be around 10 to 20 percent and then slowly decreasing
with time and Cheyenne County had the highest pops in this gradient
line. The good news is that this cold airmass will cool us off over
the next week with highs in the 60`s and 70`s tomorrow and some
potential low 80`s in the Panhandle on Wednesday as the upper level
ridge begins to slowly build over the next 48hours or so. However,
by Tuesday afternoon another shortwave will be pushing northeast
giving rain chances to the areas west of I-25 and then possibly
translating those rain chances eastward by the late afternoon/early
evening into the lower elevations east of I-25. Models aren`t
necessarily "excited" about the showers caused by the shortwave
since there is very little CAPE and the vorticity maxima`s move
quickly through our area providing very little support. The more
garden variety thunderstorm to brief shower over our forecast area
looks to be the likely scenario Tuesday afternoon through Tuesday
night.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Issued at 239 PM MDT Mon Sep 14 2026

Ahead of a Pacific upper level low a few embedded shortwave impulses
in the southwesterly flow aloft are anticipated to pass through the
area. The best resolved of these shortwave troughs is anticipated
Thursday and will be attended by an impressive fetch of monsoonal
moisture. Ensemble PWAT values are progged to be near or just
outside of the climate maximum. Widspread 1 to 1.5 inch PWAT values
could lead to proficient rainfall potential. GFS forecast soundings
for some spots in the NE Panhandle feature a near saturated profile
with an impressive depth to the warm cloud layer for this area. The
CAPE values are rather paltry however. At the surface a weak lee
cyclone may develop and move NE over the Panhandle locations. Behind
this cyclone cooler air filters in to drive afternoon temperatures a
few degrees lower than Wednesday. The WPC has a marginal risk of
excessive rainfall over our area. Fog is a possibility in the
morning hours east of I-25.

Friday continues the cloudy and wet trend while the Pacific trough
continues to inch eastward. The fetch of monsoonal moisture
continues with widespread light showers and thunderstorms. The near
surface layer does dry out limiting greater rainfall potential. The
marginal risk of excessive rainfall continues in the latest outlook.

This weekend the trough begins to flatten and decay as it nears our
neck of the woods. Continued shower and storm activity in the
afternoon and evening hours is likely to continue, but by this point
the monsoonal flow could be largely shut off with us on the dry
western side of the trough. Southwesterly flow continues in the
very long term with more embedded shortwave troughs which could
provide a stormy start to the work week.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1145 AM MDT Mon Sep 14 2026

Dry air will be pushing eastward as the upper level low over
Montana begins to lift to the Northeast. Theres a stream of
light showers following the cold front that moving into the
Central Plains. Theres a potential for an occasional shower
to move over KCYS, KSNY, and KAIA as these showers move north-
northeast from the Rocky mountains. These showers weren`t put
into the TAFs with the exception on KSNY as they are the most
likely to see actual rain from these showers. As the dry air
moves east we should start to clear out over the Panhandle.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 8 PM MDT this evening for WYZ417>423-
     427-432-433.
NE...Red Flag Warning until 8 PM MDT this evening for NEZ434>436.

&&

$$

SHORT TERM...MM
LONG TERM...RV
AVIATION...MM