626
FXUS65 KCYS 061722
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1122 AM MDT Sat Sep 6 2025

.KEY MESSAGES...

- Patchy frost possible across the area Saturday morning. Areas
  of smoke and haze will persist through Saturday.

- Warmer temperatures will develop for the Sunday through Friday
  period, with chances for isolated to scattered late day
  showers and thunderstorms nearly every day.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 233 AM MDT Sat Sep 6 2025

Current temperatures early this morning are a bit cooler than what
models have been suggesting over the last few days. As a result,
used a blend of NBM 25th and 10th percentiles to bring morning lows
down as effective radiational cooling takes place. Given the calm
conditions, patchy frost will likely develop across much of the
Nebraska panhandle as lows fall into the 30s. A few lower elevation
spots and valley locations in southeast Wyoming may also see some
patchy frost Saturday morning. Frost should dissipate rather quickly
as temperatures warm up fast with an upper-level ridge building over
western Wyoming.

With a an upper-level ridge beginning to build over western CONUS,
700 mb temperatures will rise back into the double digits for most
of the CWA. This will lead to high temperatures about 5 to 10
degrees warmer than Friday with highs mainly in the 70s for most
cities. With northwest flow expected to continue aloft, Canadian
wildfire smoke will persist through the day Saturday, leading to
hazy skies. Near surface smoke may also persist for areas west of
the Laramie Range where light winds will keep air a bit stagnant.
For the most part, the upper-level ridge will limit precipitation
chances, however, a weak disturbance moving through the ridge could
spark a few high terrain storms during the afternoon and
evening hours. As the disturbance moves across Wyoming, light
showers could linger into Saturday night.

By Sunday, the upper-level disturbance will be over the CWA. This
will provide lift as well as a little mid-level moisture needed
for storms to develop. Coverage of storms will be more
widespread compared to Saturday, with storms developing in
Wyoming by early afternoon and eventually spreading east into
Nebraska by late afternoon. There is a bit of instability
present, so thunderstorms are likely with a few potentially
containing small hail and gusty winds. Storms will continue into
the evening hours.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 202 PM MDT Fri Sep 5 2025

Sunday...As ridging aloft develops over our counties, return
southeast low level flow develops, advecting low and mid level
moisture across our counties, and producing scattered afternoon and
evening showers and thunderstorms, mainly west of I-25. The warming
trend continues with 700 mb temperatures near 13 Celsius.

Monday...The warming trend continues with low amplitude ridging
aloft and 700 mb temperatures rising to near 13 Celsius. With drying
at the low and mid levels, no precipitation is expected.

Tuesday...As the ridge aloft transitions over the Central Plains
states and our flow aloft turns southwest, temperatures will remain
about the same. Enough low and mid level moisture for isolated to
widely scattered late day showers and thunderstorms, mainly west of
I-25.

Wednesday...Southwest flow aloft strengthens, and with warm
temperatures aloft providing convective inhibition, only isolated to
widely scattered late day showers and thunderstorms will be
possible, mainly west of I-25. High temperatures about the same as
on Tuesday.

Thursday...South southwest flow aloft prevails, and with adequate
low and mid level moisture, we expect to see isolated to widely
scattered late day showers and thunderstorms. Perhaps slightly
cooler compared to Wednesday due to more clouds and precipitation.

Friday...As the shortwave trough aloft pivots into western Colorado,
the flow over our counties will turn southerly, advecting more low
and mid level moisture and clouds into our counties, and producing a
chance of late day showers and thunderstorms. With more cloud cover,
temperatures will be a bit cooler compared to Thursday.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1122 AM MDT Sat Sep 6 2025

VFR conditions will prevail for a majority of this TAF period across
all terminals in our CWA along with generally light winds. However,
smoke from Canadian wildfires may drift into our CWA once again,
leading to hazy skies, with surface smoke potentially reducing VIS
slightly at times, with the greatest chances for our western
terminals. A few widely scattered storms may develop later this
afternoon and move into the vicinity of southeast Wyoming
terminals.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Air Quality Alert until 1 PM MDT Sunday for WYZ104-109-111>113.
NE...None.

&&

$$

SHORT TERM...SF
LONG TERM...RUBIN
AVIATION...RZ