textproduct: Grand Junction

KEY MESSAGES

- Showers and storms will continue this week each afternoon and evening, with coverage becoming more widespread by Tuesday and Wednesday.

- Primary threats include heavy rainfall, lightning, and outflow winds (30-40 mph). Some small hail will also be possible.

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

DISCUSSION

Issued at 1003 PM MDT Sun Jul 19 2026

A stagnant high-pressure system remains parked over the area. This is leading to many rinse and repeat days when it comes to the current forecast. Shower and thunderstorm chances remain each afternoon and evening, at least for the first half of the week. Shower activity appears to become more widespread by Tuesday and Wednesday as PWATs increase to upwards of 200% of normal in some places at that time. Primary threats continue to be heavy rainfall, lightning, and gusty outflow winds (35-45 mph). Small hail is also a possibility. With that being said, depending on where these storms choose to materialize, they introduce a threat for flash flooding and debris flows. This remains a concern for areas with vulnerable terrain, including recent burn scars in addition to burn scars from previous years. For greater detail on the flash flooding risk, see the hydrology section below.

By midweek, the high-pressure system will shift slightly, altering our storm tracks. While storms have recently been taking an unusual east-to-west path, the new pattern will likely steer them up from the south. Because high-pressure systems circulate clockwise, this shift will pull deep moisture further northward, extending our chances for rain.

As far as temperatures are concerned, daytime highs will continue to be above normal for the next few days, with near normal temperatures expected Wednesday and beyond.

A special note for outdoor enthusiasts: Please continue to monitor the forecast and adjust your plans as needed. These storms can develop rapidly, bringing sudden hazards. Your best bet is to head out early in the morning, as storm activity typically strengthens in the afternoon. Always ensure you have multiple ways to receive weather warnings.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 604 AM MDT Mon Jul 20 2026

Isolated showers and thunderstorms will develop over the higher terrain across the region between 18Z and 00Z with more scattered coverage over the Uinta Mountains in northeastern Utah and over the San Juan Mountains in southwestern Colorado. This convection will end by about 06Z Tuesday. Included PROB30 in most TAFs along and south of I-70. Expect brief periods of MVFR in precipitation. Otherwise, look for VFR conditions and light winds through the TAF period.

HYDROLOGY

Issued at 1003 PM MDT Sun Jul 19 2026

Anomalous moisture remains entrenched across portions of eastern Utah and western Colorado. Rainfall rates of 1-2 inches per hour will be possible with 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 have reported 0.5 to 1.0 inches of rain within 30 minutes which is more than sufficient to create issues in our steep, rocky terrain. This terrain will further exacerbate areas that are already susceptible to flash flooding. This environment has heightened awareness over recent (or actively burning) fires due to the burnt ground's inability to absorb moisture under heavy rainfall. As such, we will continue to emphasize the potential for flash flooding and debris flows in this regime. By Tuesday and Wednesday, precipitation coverage appears to become more widespread, which will extend the flash flooding concerns through at least mid week.

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.