textproduct: Grand Junction

KEY MESSAGES

- This week will see daily afternoon thunderstorm chances, particularly along the higher terrain of western Colorado and eastern Utah.

- Localized heavy rainfall continues to pose a threat to flash flooding over burn scars and susceptible terrain.

- Daytime highs will run ~5 to 10 degrees above normal to start the week and will gradually increase through Friday.

DISCUSSION

Issued at 949 PM MDT Mon Aug 24 2026

High pressure will continue to slide westward into the Desert Southwest through the end of the week. This will contribute to a gradual warming and slight drying trend, as the deeper plume of monsoonal moisture is shifted to the east. That said, surface moisture will linger under the high, with forecast PWAT values remaining 100-150% of normal through the end of the week. Limited dynamic forcing means that showers and thunderstorms will rely on orographic lift to form, resulting activity firing off the higher terrain each afternoon through the end of the week. Frequent lightning and gusty winds will be possible from any storms that form, along with localized heavy rain. Should storms form over a sensitive area, or train over the same area, flash flooding will be possible, along with debris flows associated with recent burn scars. As the high settles into the Southwest, temperatures will warm a degree or two each day. By the end of the week, highs will be 5-10 degrees above normal for late August.

A pattern shift will be possible late this week into the coming weekend, as a deep trough approaches the West Coast. Ahead of this trough, the tightening pressure gradient will lead to stronger winds. There is potential for at least localized Critical Fire Weather conditions, but that all depends on whether drier air is able to push in, or if wetter conditions will prevail. Guidance is in poor agreement at this time, as some deterministic and ensemble solutions favor wetter conditions, while others are running drier. It's something to stay tuned for. Troughing gradually overspreads the western CONUS through the weekend, introducing a wetter and cooler pattern. Current blended guidance is indicating temperatures near to a few degrees below normal as we move into early September.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1125 PM MDT Mon Aug 24 2026

Shower activity will diminish through the overnight hours across northeastern Utah and northwestern Colorado. Look for showers and thunderstorms to redevelop over the higher terrain across the region between 16Z and 00Z impacting mainly the mountain TAF sites. Primary threats continue to be gusty outflows, lightning, and localized heavy rainfall producing brief periods of MVFR conditions. Otherwise, expect VFR conditions and light terrain driven winds through the TAF period.

GJT WATCHES/WARNINGS/ADVISORIES

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