931
FXUS65 KCYS 081129
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
529 AM MDT Tue Sep 8 2026

.KEY MESSAGES...

- Chances for light and brief showers with temporary strong wind
  gusts possible this evening.

- A temporary drying trend begins Tuesday and possibly
  continuing through the end of the week.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 254 AM MDT Tue Sep 8 2026

Some weak showers persist following a surface cold front that is
expected to stall along the WY/CO border. The upper level low is
directly north of our forecast area along the Canadian Border ever
so slowly pushing east. A 700mb cold front will push through
tomorrow dropping 700mb temperatures from 12/14C down to around 6/7c
around peak heating to the evening time. Due to the kind of late
arrival surface temperatures will only be 4 degrees cooler from the
previous day. This cold front may create some light showers in the
southern counties where low level moisture gets trapped underneath
our expanding ridge. Hi-res models depict a swath of 200-500 joules
of CAPE in some areas but depending how fast the winds switch from
southwest to west as the upper level low pulls further away from us
some clouds may form and may not produce any precipitation. Instead
we will get gusty outflows and microburst in the evening into the
overnight hours. Hi-res guidance clears the showers out by 06z or
midnight. Wednesday, we will continue to be predominantly in our
westerly downsloping flow. The downsloping flow will keep the colder
airmass above us from dropping the temperature below 70 degrees. The
daily high temperature is expected to be mostly in the 70`s with the
Nebraska Panhandle in the low 80`s.  Overnight temperatures will be
a bit cooler with temperatures in the 40`s and 50`s.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 254 AM MDT Tue Sep 8 2026

The ridge continues to elongate through the middle of the work
week, placing our area in primarily zonal flow aloft and
therefore mostly dry conditions. A warming trend is expected on
Thursday and Friday as a secondary ridge begins to build across
the Desert Southwest. Will have to monitor fire weather
conditions on both of these days as ensemble guidance is hinting
at gusty westerly winds of 25-35 knots combined with daytime RH
values dipping to 15- 20%.

Heading into the weekend, we start to bring back the fetch of
monsoonal moisture ahead of a shortwave trough digging across the
Pacific Northwest, placing Southeastern Wyoming and Western Nebraska
in WSW flow aloft. With the lack of signal for any substantial
forcing from long-range ensemble guidance, no widespread (and
beneficial) precipitation is expected. However can expect a slight
cooling trend with this next push of moisture and the usual diurnal
pattern of scattered afternoon and evening showers and
thunderstorms.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 530 AM MDT Tue Sep 8 2026

Showers are slowly dissipating between KSNY and KAIA this
morning with the ceiling between 095 and 15,000ft expect clouds
to clear out through the morning. In the afternoon a surface low
will move across the Panhandle making the winds light and
variable. After 23z light showers will form over KCYS and move
East-Northeast possibly moving over KBFF, KAIA, and KSNY. Its
unsure if these showers will produce virga or raindrops so VCSH
was used to describe this uncertainty. The skies will clear out
through the night and into tomorrow morning. Wind gusts will be
erratic under these showers. For KRWL and KLAR only wind gusts
will reach up to 25-30kts by the afternoon and last until around
01z.

&&

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

&&

$$

SHORT TERM...MM
LONG TERM...NB
AVIATION...MM