textproduct: Grand Junction

KEY MESSAGES

- Expect showers and thunderstorms each afternoon and evening through early next week. Wind gusts upwards of 45 mph and small hail are possible with these storms.

- Localized heavy rainfall will have the ability to produce flash flooding and debris flows in vulnerable terrain, including areas near and downstream of burn scars.

DISCUSSION

Issued at 1047 AM MDT Fri Jul 17 2026

There will be very little shift in the pattern aloft over the next few days. Moisture consisting of PWAT values around 150-200 percent of normal has become established across the region. This moisture is supporting daily showers and thunderstorms during the afternoon and evening hours. Initiation will be favored over the higher terrain before spreading over the valleys as outflows develop. Additional development is possible where these outflows collide with each other and the higher terrain. Isolated storms and scattered showers may linger through the overnight. Lightning and heavy rain will be the primary threats, with small hail and gusty outflow winds up to 35-45 mph on the table as well. Heavy rainfall could result in flash flooding and debris flows, especially over area burns scars. The hydrology section below discusses this risk in greater detail. These storms can develop quickly, so be sure to monitor the forecast and have a way to receive weather alerts, especially if you are visiting or reside below terrain that is vulnerable to flash flooding, including downstream of active fires. This pattern will continue into next week, so expect similar weather each day through then. The only difference will be slight variations in where the convection forms and drifts off the terrain. Temperatures will run near normal to slightly below normal for the next several days.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 520 AM MDT Fri Jul 17 2026

Increased moisture in the region will bring another day of showers and thunderstorms. Activity has begun in the southern mountains, and will increase in coverage through the afternoon. After 00Z activity will gradually diminish. Concerns are lightning, gusty outflow winds, and brief periods of heavy rainfall. There is a low probability of MVFR conditions occurring with heavier rainfall, but otherwise VFR conditions are expected to prevail. Winds will become light and variable overnight.

HYDROLOGY

Issued at 1047 AM MDT Fri Jul 17 2026

Anomalous moisture has become established across portions of eastern Utah and western Colorado. Rainfall rates of 1-2 inches per hour will be possible with the stronger storms. These rates could lead to flash flooding and debris flows especially over recent burn scars.

Storms over the last few days have helped prime lower levels of the atmosphere and saturate the ground where rain was observed. Several locations across southwest Colorado reported over 0.5 inches of rain within 30 minutes; which is more than sufficient to create issues in our steep, rocky terrain that is already susceptible to flash flooding. This environment also triggers heightened awareness over recent (or actively burning) fires, due to the burnt ground's inability of absorbing moisture under heavy rainfall. As such, we continue to emphasize the potential for flash flooding and debris flows in this regime.

As a reminder: Keep an eye on our forecasts through the end of the week and stay tuned for updated hydrology alerts if visiting or if you reside below vulnerable terrain to flash flooding and/or debris flows. Storms across the west develop quickly, leaving little room for lead time in flashy terrain.

GJT WATCHES/WARNINGS/ADVISORIES

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