textproduct: Western and Central Wyoming

KEY MESSAGES

- Widespread elevated to critical fire weather conditions are anticipated today due to wind gusts of 30 to 40 mph and humidity as low as 10 percent.

- Seasonal temperatures Thursday warm several degrees on 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 surface pressure gradient will tighten, especially west of the Divide, in response to 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 /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1235 PM MDT Wed Jun 17 2026

With relatively dry northwest mid-level flow over Wyoming today, VFR conditions are expected at all TAF sites through the forecast period (18/18Z). Somewhat of a tale of two environments though with the continental divide as the boundary between the two. Western and southwest WY will continue to be breezy/windy and gusty with dry conditions and very few clouds. Gusts around KRKS will continue with 30-45 kts through about 18/03Z, with lighter gusts of 20-30 kts at KPNA/KBPI/KJAC. KLND and KRIW will see similar gusty and dry conditions through about 18/01Z before a cool front/boundary from northern WY shifts the wind to northeast for a few hours during the evening. KCOD and KWRL are already seeing gusty north winds behind the front/boundary. As clouds develop more this afternoon, ceilings across northern WY will lower, but should remain VFR unless a stray virga shower passes near the site. KCPR will also see a shift of wind dir from NW to NNE early this evening as the boundary moves south. At all locations, winds should diminish to under 12 kts by 18/06Z.

Thursday will see a similar set up and wind pattern though wind speeds and gusts should be a lower than today. KCOD/KWRL will continue with north winds during the afternoon, with the boundary moving back into central WY early Thursday evening. High clouds will move into southwest WY Thursday morning, and spread over the rest of the area during the afternoon.

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.