textproduct: Grand Junction

KEY MESSAGES

- Drier air begins to move in today, limiting chances for showers and thunderstorms to the higher terrain this afternoon.

- Deep surface moisture will keep chances for heavy rain in the forecast, along with the potential for flash flooding and debris flows over recent burn scars and other vulnerable areas.

- Temperatures will warm through the end of the week, reaching near- normal by Friday.

DISCUSSION

Issued at 1027 PM MDT Mon Aug 31 2026

Troughing along the West Coast and ridging across the Southeast will keep eastern Utah and western Colorado under southwesterly flow through the end of the work week. This will pull in drier air, gradually reducing precipitation chances through the end of the week as surface level moisture is scoured out. That said, chances for showers and thunderstorms will remain each afternoon, primarily across the higher terrain. Enough surface moisture is expected to stick around Tuesday to keep the potential for heavy rain around, as well the potential for flash flooding in vulnerable locations. As drier air continues to push in, the main threat with storms will transition to that of gusty outflow winds. Lightning will be a threat throughout the period with any storm. Temperatures will warm day by day as we dry out, reaching near-normal values by the end of the work-week.

A strong closed low is forecast to drop out of the Gulf of Alaska by the weekend, forcing the West Coast trough to retrograde slightly. This will allow the Southeast ridge to also expand westward, and ultimately the flow over eastern Utah and western Colorado will shift to a more southerly direction. This will once again tap into deeper monsoonal moisture, bringing a return to wetter and cooler conditions. Ensemble and deterministic guidance does remain in decent agreement regarding a plume of above normal PWATs reaching eastern Utah and western Colorado by Saturday, but there does remain some uncertainty. Changes with the tropical system activity in the Pacific could substantially alter this forecast, so be sure to stay tuned for updates on how this weekend's forecast develops.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1135 PM MDT Mon Aug 31 2026

CLouds will continue to drift eastward overnight. Clouds will start lifting where broken to overcast skies are currently. By morning, scattered to occasional broken skies will remain. Some limited convection is possible in the afternoon but coverage will be much less than that seen recently. Do not anticipate any affects for TAF sites.

HYDROLOGY

Issued at 1027 PM MDT Mon Aug 31 2026

Although drier air begins to move into the region, lingering mid- level moisture and daytime heating will keep afternoon thunderstorms in the forecast for the higher terrain regions Tuesday. Hence, a localized flash flooding threat remains. Recent burn scars and other vulnerable terrain, including slot canyons, continue to be most susceptible.

GJT WATCHES/WARNINGS/ADVISORIES

CO...None. UT...None.