textproduct: Western and Central Wyoming

KEY MESSAGES

- Light rain showers continue overnight from Sweetwater through Fremont/Natrona to Johnson Counties through sunrise Monday morning.

- Near freezing to just below freezing temperatures for western Valleys Monday morning, coldest across the upper Green River Basin.

- Light accumulating snow for western mountains above 10kft, low confidence (<10%) of any reaching the Teton/Togwotee Passes.

- Gusty winds over 50 mph likely for the wind prone areas east of the Divide Monday afternoon and early evening.

- Limited precipitation chances Tuesday onward with increasing fire weather risk and warming trend through the holiday weekend.

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 Montana 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 /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 450 AM MDT Mon Jun 29 2026

VFR conditions expected throughout the entirety of the TAF period at all locations. Increasing winds to start the period, seeing gusts up to 25kts at COD/CPR, with others to following by 14-17Z. Highest winds expected for COD aided by the westerly gap flow up to 45kts, with all others up to 30-35kts. Highest winds during the afternoon hours, starting to diminish after 02-03Z towards sunset. Still elevated at COD, all others down to 10-15kts or less with all locations becoming light less than 10kts after 06-09Z, latest at COD. Beyond the winds, passing showers for COD/WRL between 15-21Z, with the highest chances (70-80%) more predominantly at JAC during that time, to include likely MVFR ceilings during periods of rainfall. PNA will have the least chance ~10-20% carrying only VCSH. Mid level ceilings scatter out post 02-03Z clearing there after 06-09Z through the end of the period into Tuesday morning.

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

RIW WATCHES/WARNINGS/ADVISORIES

None.