085
FXUS65 KRIW 021001
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
401 AM MDT Sat Aug 2 2025

.KEY MESSAGES...

- Yet more rounds of showers and thunderstorms across western
  and central Wyoming today and Sunday.

- Winds are more limited today, slightly decreasing the fire
  weather threat in the short term.

- Ridging shifts westward into the Four Corners during the
  upcoming week, bringing increased heat, and drier air at the
  surface.

&&

.DISCUSSION...
Issued at 214 AM MDT Sat Aug 2 2025

The ridge that has been sitting across the central US, which has
given us a feed of monsoon moisture will be finally shifting
west the next couple days. Today will be the last widespread
moisture day, with scattered showers and thunderstorms
developing across the state during the early afternoon. Coverage
will be similar to the past couple days, with PW values still
near where they should be this time of year. Some thunderstorms
may again get strong, but these are getting more limited to the
open areas along and downwind of the Bighorn Range. Fire
weather concerns are somewhat elevated as humidity only
reaches 15 to 20% and some wind gusts near 20 in the afternoon,
but the very dry fuels across the state would still be very
responsive to any activity, including lightning.

Sunday will see the leading edge of drier desert air from the
desert southwest feeding into the state. This will start to
limit shower activity, with more shower activity not reaching
the ground, especially across SW WY. Best shower and
thunderstorm chances Sunday will be along and downwind of the
Absarokas and Bighorn Ranges during peak heating hours. Drier
air will also begin to increase the fire weather threat across
SW WY Sunday afternoon, as humidity levels west of the divide
tick downward to 10 to 15%, while more frequent wind gusts start
to show up.

By Monday the ridge will be settled on the Four Corners,
shutting down the moisture and increasing the heat. A passing
shortwave to the northwest may tap the last remnants of moisture
for showers along the Absarokas, but there won`t be much left to
precipitate by this time. This will bring temperatures upwards,
ranging form the upper 80s west of the divide, to the low to
mid 90s east. Humidity levels will be 8 to 14% each afternoon,
and wind gusts of 20 to 25 mph will be possible, so we may have
to contend with an extended period of elevated to critical fire
weather conditions.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 400 AM MDT Sat Aug 2 2025

VFR conditions should prevail through 18Z Saturday. The afternoon
will be another day of scattered afternoon showers and
thunderstorms, mainly from 20Z Saturday through 02Z Sunday. The best
chance of a shower or storm looks be in vicinity of KCOD, but just
about all terminals will have at least a 1 in 5 chance of an
afternoon thunderstorm or shower. As a result, we have gone with
PROB30 groups for almost all terminals since individual showers and
storms remain hard to pinpoint. The smallest chance will be in
vicinity of KJAC, with around a 1 in 5 chance of a shower and less
than a 1 in 7 chance of a thunderstorm. Here we have opted for a
VCSH group. With drier air at the surface, the main threat from any
thunderstorm would be wind gusts past 40 mph. Any thunderstorm or
even shower could produce wind gusts past 40 mph this afternoon.
Most convection should end after sunset tonight with largely VFR
conditions prevailing from 04Z to 12Z Sunday.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC
for the latest information on icing and turbulence forecasts.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Straub
AVIATION...Hattings