textproduct: Western and Central Wyoming

KEY MESSAGES

- Warmer today. Most areas remain dry, but weather models are hinting at a few weak showers or thunderstorms moving across the area late afternoon into the evening today.

- Warming trend and mainly dry conditions for the remainder of the week and into the weekend with only limited shower activity each afternoon for northern mountains.

- Elevated fire weather conditions persist, with low humidity values and slight breeze each afternoon this week.

UPDATE

Issued at 1217 PM MDT Tue Jun 30 2026

Highs are about 10 degrees warmer today, approaching normals for the end of June. Some weather models are producing weak showers and thunderstorms between 1pm and 10pm today, associated with a shortwave moving through from the southwest. The main impact from any of these would be gusty outflow winds, generally up to 35 mph. Elevated fire weather conditions will also be in place, especially around Natrona County as breezy winds 20 to 25 mph occur with minimum humidity 10 to 15 percent.

DISCUSSION

Issued at 100 AM MDT Tue Jun 30 2026

IR currently depicts the main upper level low pushing northeast into the upper Great Plains as the troughing in its wake fills with decreased divergence aloft. WV continues to show distorted fingers of the PFJ, mainly into Canada now with little support to the aforementioned upper level low. Radar activity has diminished for the overnight hours as skies have improved in its wake. This will allow for one more cold morning Tuesday allowing for western valleys to see mid 20s to mid 30s with minor frost likely for areas of the upper Green River for the usual suspects between Pinedale to Bondurant.

Otherwise, southwest flow continues aloft Tuesday and Wednesday with a couple minor shortwaves clipping the northern counties but mainly into Montana. Each afternoon and evening will see some limited coverage in shower activity for the northern mountains (10-20%) with a rumble of thunder even less likely <10% due to weak CAPE values less than 100 J/kg. Better chance coming in from the southwest later in the evening towards sunset from Sweetwater to Fremont Counties (30-40%). This pattern continues for the remainder of the work week as a warming trend and mainly dry trend extends through the weekend. A more zonal pattern by the weekend as the high to the south builds in further north increasing convergence aloft and weaker flow. Afternoon high temperatures back to the 80s east of the Divide and 70s to the west for the holiday weekend with no significant winds even to speak of. Each afternoon/early evening will see slight breezes up to 20-25 mph for wind prone areas east of the Divide but otherwise calm for Wyoming standards. Even with low relative humidity values, fire weather concerns will be limited to elevated throughout the week and weekend. This upper level high continues to build in from the south into next week with some longer term model ensembles showing some record heat coming by mid to end of next week, welcome to July....

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1125 AM MDT Tue Jun 30 2026

With a weak disturbance over southwest Montana, and another one moving from northern Utah into central WY this afternoon, isolated to very scattered showers are expected today over western and central WY. All TAF sites have VCSH in the forecast at various times this afternoon and early evening as a result. The primary impact from potential storminess will be lowered ceilings to about 5-6K ft (general VFR with marginal MVFR) and gusty outflow wind over 40 kts. Thunderstorm chances are at best 10-15 percent, so have stayed with VCSH. Breezy SW winds from southern into central WY will give way to gusty NW winds this evening. In addition, a weak cool front will push southward into the Bighorn Basin, and from KBYG to CPR before washing out overnight.

Skies mostly clear out overnight, but another disturbance from the Great Basin will increase clouds mid-day Wednesday from west to east. Isolated to scattered showers and thunderstorms return to western and northwest WY Wednesday afternoon after 01/20Z. Southern into central WY will remain partly cloudy with dry SW wind, with northwest outflow during the evening hours.

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

RIW WATCHES/WARNINGS/ADVISORIES

None.