208
FXUS65 KRIW 300502
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1102 PM MDT Mon Jun 29 2026

.KEY MESSAGES...

- Light rain/mountain snow continues over northwestern Wyoming,
  ending through the rest of the evening.

- Gusty winds will also begin to subside through the evening,
  with the strongest gusts occurring through 8PM.

- Another night of cool temperatures tonight. Western valleys
  and basins will likely see a frost, with lows in the mid-20s
  to mid-30s.

- Trending warmer this week. Dry and breezy conditions bring
  elevated fire weather concerns. Rain chances will occur, but
  are very limited, so most areas remain dry.

&&

.DISCUSSION...
Issued at 200 AM MDT Mon Jun 29 2026

WV imagery continues to show the deep elongated trough across
the Rocky Mountain West, with colder cloud tops through the CWA
depicted on IR. Weak, distorted fingers of the PFJ aid in
supporting the mainly closed low over MT with divergence aloft
lacking in strong support of any significant weather. A minor
S/W is pushing through the CWA overnight giving way to a few
light rain showers stretching from eastern Sweetwater northeast
to Johnson County that will slowly push east out of the area by
sunrise Monday morning. Limited in rainfall if any, due to dry
surface conditions, will mainly see an impact of lower cloud
cover through a couple hours post-sunrise. Less clouds west of
the Divide will give way to better radiational cooling to allow
for colder temperatures. Western valleys will see near freezing
to just below freezing temperatures near sunrise, but only
touching it for less than hour not needing any cold temperatures
hazards. The coldest spots will be the usual Upper Green River
Basin from Pinedale to Bondurant. Beyond the temperatures, the
next subtle mid-level trough will give way to some light snow
above 10kft for western mountains, highest for the Tetons and SW
Yellowstone of 2-3 inches (50-60%). Other parts of Yellowstone
to the Gros Ventres and Winds could see an inch or so but lower
confidence (30-40%). CAMs seem to be a bit bullish on these
amounts with much of the impacted areas into MT, to include the
Beartooth Pass.

Impacts east of the Divide will be of course wind, with the
passing shortwave. Increasing gusts by mid-morning over 30 mph
to peaking at over 50 mph by noon time. Highest wind speeds
expected for the wind prone areas from eastern Sweetwater to
Natrona Counties to include South
Pass/Greens/Rattlesnakes/Casper Mountain that have a decent
chance to breaking 60 mph (30-40%), but not worthy of any wind
products for these higher elevations. Other areas of note will
include the Cody/Lander Foothills pushing 50 to 55 mph that will
keep an eye on to hit high wind criteria of 58mph (~10-15%).
Winds will of course, decrease towards sunset Monday evening but
remain elevated in these same areas through about midnight.
Monday afternoon will also be the "coolest" day of the week,
with 70s east of the Divide and 50s mainly to the west
(Yellowstone down to the 40s, and even upper 30s for the
northeastern part for Lamar Valley). The ample herds of Buffalo
will welcome the reprieve of the heat.

Beyond Monday, expect a warming and mainly dry trend for the
rest of the week and into the holiday weekend of America`s 250th
birthday celebration. The aforementioned upper level trough will
fill with decreasing divergence aloft and push northeast. The
West Coast will have another deepening L/W trough set up and
remain with weak ridging to the east of the CWA. A few subtle
shortwaves will push to the north and northeast of the area that
will see some weak chances for northern mountains of the
Absarokas and Bighorns (20-30%), but storm activity looks to be
limited to the higher elevations with minimal accumulations
expected. The other thing to keep an eye on will be increasing
fire weather risk with warming temperatures/lower humidity
values, but no significant wind looks to be forecasted beyond
Monday. Independence Day and entire weekend looks to be a
seasonable to just above seasonable day in terms of
temperatures, with afternoon highs into the 80s east of the
Divide and 70s to the west. Limited storm chances look to be
confined to just the northern Bighorns, but stay tuned for any
updated forecast changes in the coming days.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1100 PM MDT Mon Jun 29 2026

VFR conditions across nearly all terminals for the start of the TAF
period. The one exception to this is KJAC where light rain shower
have lingered through the evening. Ceilings have gradually lifted
but are likely to linger through much of Tuesday morning. That being
said a brief period of MVFR ceilings cannot be ruled out at times.
Winds will continue to decrease across all terminals with a light
breeze through the overnight. Winds are expected to increase some to
15 to 25 knots around 14Z mainly at KCPR and KCOD. Showers begin
developing after 18Z Tuesday mainly across western and southwestern
WY. Coverage begins to spread farther north and east after 00Z
Wednesday with slight chances possible at KLND, KRIW, KWRL, and
KCPR. Overall showers are expected to be light with minimal impacts
but a few gusty outflow winds cannot be ruled nearby any developing
showers. Dry conditions return after 03Z for all terminals and
prevailing into the end of the TAF period. Mountains are likely to
be obscured especially across western WY with conditions improving
during the day Wednesday.

&&

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

&&

$$

DISCUSSION...Lowe
AVIATION...Dziewaltowski