textproduct: Western and Central Wyoming

KEY MESSAGES

- A dry cold front continues to move southward this morning, leading to cooler highs today. Areas east of the Continental Divide will be 5 to 15 degrees cooler.

- Seasonal temperatures Thursday warm several degrees Friday ahead of an incoming Pacific weather system. Dry conditions prevail both days along with a breezy west wind over the high deserts of southwestern Wyoming.

- Precipitation chances return for the weekend, with areas of northern Wyoming the most likely to see scattered showers and thunderstorms.

DISCUSSION

Issued at 315 AM MDT Wed Jun 17 2026

A cold front is currently progressing southward over areas east of the Divide, having already reached Worland and the northern half of Johnson County. Very weak showers also continue over northern Johnson County and are expected to end in the next hour or so. The front will continue southward, reaching Casper and Riverton around 09Z/10Z this morning, and reach the Divide by sunrise. The sfc pressure gradient will tighten, especially west of the Divide, irt the front. Gusty north to northwest winds, with gusts of 30 to 45 mph, will continue over northern portions in the wake of the front. These areas are prone to these post-frontal conditions of higher winds. Additionally, northwest winds will increase over southern portions, including the Upper Green River Basin, with gusts of 25 to 35 mph after 15Z. Winds will continue to increase across the CWA, with gusts of 30 to 40 mph returning for most areas after 18Z. Showers and isolated thunderstorms will be possible over northern portions between 21Z and 06Z, as an area of channeled vorticity moves over the area from the northwest. Elevated to critical fire weather conditions will be in place again this afternoon due to the winds and generally dry conditions. However, temperatures will be cooler across the CWA with areas east of the Divide 5 to 15 degrees cooler due to the cold front. Southern portions will be at the most risk, with the widespread northwest winds gusting up to 40 mph and critical RH values as low as 10%.

Conditions will remain more seasonal Thursday, with winds not being so strong. Gusts up to 30 mph look to be confined over areas west of the Divide in the afternoon. A ridge looks to build over the region from the west Friday, marking a return for temperatures in the upper 80s and lower 90s. Fire weather conditions will continue to be elevated to critical on these days, with critical RH values (<15%) occurring across much of the CWA by Friday. Chances for precipitation return for the weekend, as the remnants of a Pacific low move over the region. For now, the northern half of the CWA looks to have the best chances to receive any precipitation with rainfall amounts of 0.30" to 0.60" currently in the forecast over these 2 days. Locally heavy rain could occur from these storms, as precipitable water values of 0.60" to 1" are forecasted. Precipitation chances could linger into Monday, as the system is slow to make it over the Central Plains. A slower system like this could increase the chances for precipitation and provide some much needed rainfall across the area.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 448 AM MDT Wed Jun 17 2026

SKC skies this morning across the area to start the forecast, as a cold front reaches the Divide and becomes stationary. Terminals east of the Continental Divide see a post- frontal northerly wind steadily increase between 15Z and 19Z and linger through much of Wednesday evening. Shortwave energy, combined with favorable 700/500mb layer moisture, generates some light showers and increased cloud cover across northern Wyoming late in the afternoon and into the evening. Confidence remains too low to include a PROB30 group for KCOD/KWRL. Mountain top obscurations will be common over the Bighorns as a result of these increased clouds. West of the Divide terminals see wind gusts 25-35kt develop between 14Z and 18Z. These terminals see wind diminish with the setting sun around 03Z.

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

FIRE WEATHER

Issued at 315 AM MDT Tue Jun 16 2026

A dry cold front is moving over areas east of the Divide early this morning and will reach the Divide by sunrise. Post-frontal winds over northern zones will briefly decrease after sunrise, increasing again after 0900. At the same time, northwest winds over zones 277/278/279 will begin to increase. Gusts of 30 to 40 mph will be widespread across the forecast area after 1200. RH values will be critical across the south, and portions of the Wind River Basin, as the front is expected to be stationary along the Divide through the day today.

Elevated to critical fire weather conditions continue Thursday, with critical RH values across southern zones, as well as zones 280 and 283. West-northwest winds, with gusts up to 30 mph will be confined to areas west of the Divide in the afternoon. There is a 10 to 20% chance for wind gusts over 25 mph to occur over portions of zone 280.

RIW WATCHES/WARNINGS/ADVISORIES

None.