textproduct: Grand Junction

KEY MESSAGES

- More convection today with afternoon and evening showers being the rule.

- Main concern will be flash flooding, especially over burn scars, as slow moving showers and storms bring heavy rain to the area.

- Dry conditions may start moving in towards the end of the week as do hotter temperatures.

DISCUSSION

Issued at 1007 PM MDT Mon Jul 27 2026

Models previously showed a possible downturn in activity today but latest HRRR guidance is now showing yet another day of more widespread convection. The location of the high, available moisture (, CAPE values between 800-1200 J/kg (higher in spots), and plenty of instability remain across the area and with light steering flow, here we go again. Slow moving storms will keep the threat of heavy rain in the forecast with flash flooding the biggest concern, especially across burn scars. Lightning, small hail, and gusty outflow winds of 40 to 50 mph will also be possible. Wednesday, a shortwave still looks to move across the area and one would think that with a focus for lift, convection would be widespread. Not so as models are keeping convection similar to that seen today. Will need to keep an eye on latest model runs to see how things evolve. Once the wave moves through, flow will become north through northwesterly which will start to bring in drier air. It will take a few days before this happens as residual moisture will allow some convection Thursday and Friday but a downturn is expected. The center of high pressure sets up over Utah for the weekend bringing mostly dry conditions, maybe a quick shower/storm over the San Juans. Of course, now with high pressure almost directly overhead, here comes the oppressive heat reaching 10 to 15 degrees above climo.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1124 PM MDT Mon Jul 27 2026

Storms have lingered in eastern Utah tonight, and gusty, erratic winds may still be experienced at VEL and CNY over the next three hours. Colorado terminals are not anticipated to be impacted. Storms redevelop around 18Z Tuesday, which may once again produce gusty outflow winds. Generally, gusts should be around 25 kts, but a few stronger gusts cannot be ruled out. Most storms will remain anchored to the high terrain, so higher elevation terminals are the most likely to exhibit any impacts. Localized areas of MVFR vis may be possible under stronger rainfall, but areal coverage of storms is too limited to speculate if any terminals will experience this or not.

HYDROLOGY

Issued at 1218 PM MDT Mon Jul 27 2026

Scattered slow moving thunderstorms capable of producing heavy rainfall will develop each afternoon through at least midweek. Rainfall rates of 1-2" per hour will be possible, potentially even greater for brief periods of time with stronger storms. These rates could lead to flash flooding and debris flows, especially over steep terrain and recent burn scars. Saturated soils from consecutive days for rainfall will increase the potential for flash flooding as well.

As a reminder: Keep an eye on our forecasts and stay tuned for updated hydrology alerts if visiting or if you reside near terrain vulnerable to flash flooding and/or debris flows. Dry creeks and arroyos can fill quickly and without warning from storms miles away.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Heat Advisory until 6 AM MDT Tuesday for COZ001-006. UT...Heat Advisory until 6 AM MDT Tuesday for UTZ022-024-027-029.