794
FXUS65 KCYS 292325
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
525 PM MDT Sat Aug 29 2026

.KEY MESSAGES...

- Shower and storm chances are expected through the weekend.
  Strong to severe wind gusts will be possible, with moderate to
  heavy rain likely.

- Marginal Risk for severe thunderstorms Today through Monday
  with strong gusty winds possible.

- Drying out expected going into next week with growing
  potential for elevated fire weather conditions.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 135 PM MDT Sat Aug 29 2026

A look at regional satellite and radar are showing scattered
showers and storms over the basins and crossing into the plains.
A few of these storms have been able to produce severe caliber
wind gusts and a few lightning strikes near the Rawlins and
Arlington areas. This activity is in response to a shortwave
trough passing to our north and west within the jetstream. Bulk
shear (0-10 km layer) values are in the 45 to 55 knot range
which is ample for storms to organize through the evening. A
storm or two may be able to produce large hail alongside the
attended wind threat. This activity will spread northeast into
greater parts of the southeast Wyoming and Nebraska Panhandle
areas through about 10 PM. Persistent cloud coverage this
afternoon has been hampering a greater CAPE value potential and
may be a limiting factor to more robust storms further east.

Tomorrow, Sunday, another shortwave will move along the jet
stream ahead of a negatively tilting trough skirting the US/CAN
border. A fetch of mid layer moisture along the jet from an
active monsoon will allow rounds of showers and storms to
continue to pass through SE WY and NE Panhandle locations.
There`s a 20-40% chance of some windward faces of the Snowy and
Serra Madre Ranges receiving up to an inch of rainfall from the
high resolution ensemble guidance. A few models have an inch or
greater in the Nebraska Panhandle from storms. Outside the
rainfall a few isolated severe storms could occur with the SPC
having a marginal risk category out for severe wind gusts.
Outside of storms, it will be gusty with winds out of the
southwest between 35 and 45 mph as the jet maximum passes nearby
and deep layer mixing in the afternoon brings the strong winds
towards the surface.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 135 PM MDT Sat Aug 29 2026

Monday another shortwave trough is aimed to pass over much of
the same areas. The monsoonal moisture should still be present
to allow scattered showers and thunderstorms with a conditional
risk of severe weather and heavy rainfall. The WPC has a
marginal risk for excessive rainfall over much of our area with
a sliver of a slight risk into the interior basin. There is a
shift of tails of between 0 and 1 for portions of southern
Wyoming and northwestern Colorado which could be hinting at
rainfall overachieving. The 90th percentile of 24hr rainfall
south of Rawlins is between 1 and 2 inches which makes sense
given the other guidance and the outlook discussed. The rain
should depart east and out of the area with the shortwave and
retreating ridge to the southeast through Tuesday.

We will be on a dry and warming trend through the rest of the
long term as flow aloft laxes and moisture decreases. While most
of the upper level disturbances stay west and north, there may
be enough lingering monsoonal moisture to keep a few PM showers
and thunderstorms going. Widespread rain is not expected given
the dry near surface conditions. Minimum afternoon RH values in
the mid to low 20s and gusty winds could promote elevated fire
conditions, mainly in the northern and western counties. This
drying pattern is on track to be reinforced in the very
long term as the ridge builds back west and the jetstream stays
out of our area.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 525 PM MDT Sat Aug 29 2026

Generally, VFR conditions will prevail across all terminals for
the duration of this TAF period. This is outside of any shower
or thunderstorm activity that may impact a site in Wyoming and
the Nebraska Panhandle which may drop flight categories down to
MVFR for a short period of time through the evening hours. The
nature of the coverage of the potential of heavier precipitation
may result in CIGs dropping to 5K feet or less at times, this
is covered with PROB30 groups in the TAFs. The main aviation
hazard with this activity will be the gusty and erratic winds
that accompany any storm, with speeds of greater than 40 knots,
especially for the Wyoming terminals. By about 06Z Sunday, most
of the storm activity should wane, but gusty winds will remain
overnight for KLAR and KRWL.

&&

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

&&

$$

SHORT TERM...RV
LONG TERM...RV
AVIATION...RZ