textproduct: Grand Junction

KEY MESSAGES

- Showers and storms will continue this week each afternoon and evening. The greatest coverage will occur today. - Primary threats include heavy rainfall, lightning, and outflow winds up to 40-50 mph. Hail cannot be ruled out in stronger storms.

- 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 1154 AM MDT Wed Jul 22 2026

TODAY'S FLOOD RISK:

After several days of heavy rainfall rates and reports of flash flooding and debris flows, we have decided to hoist a Flash Flood Watch for all of eastern Utah and western Colorado today into this evening. The peak of anomalous moisture occurs today along with a passing wave to tap into the moderate instability in place. Expect storms to continue to produce rainfall rates in excess of 1-2 inches per hour with burn scars especially vulnerable. Models are still scouring out much of the convective debris clouds through late morning. The eastern AZ wave arrives at peak heating to help release the instability and produce scattered to widespread convection. Storms today take on a bit more northerly track which could also help it align on terrain which has been sheltered in the E/SE flow the past few days.

STORMS TODAY AND TONIGHT:

The main concern over the next 24 hours will be a weak shortwave tracking over portions of the area. The moisture we have in place has already supported heavy rainfall, but the wave is going to bring a slight uptick (PWAT 175-215% of normal). It will also supply some lift to aid convective development, which should translate to widespread coverage. Given this environment, storms will be capable of producing strong winds, hail, and heavy rainfall. Models show the shortwave trough still tracking overhead tonight. This could support showers and storms continuing overnight. Although by late evening, the rainfall rates should be on the decrease.

LOOKING AHEAD:

On Thursday, the trough crosses the Divide leaving behind westerly flow. Plenty of moisture will still be around for peak heating, so it terrain-driven storms are likely in the afternoon. Despite some dry air behind the wave, the moisture values still support the potential for heavy rainfall.

On Friday, northwest flow will be in place and models hint at drier air trying to filter into the area. If that happens, convective coverage will likely decrease, although low-level moisture is usually slow to filter out. Another round of terrain-driven storms is possible in the afternoon.

After that, the confidence lowers as models are not sure how to handle the pool of moisture. How far south does it go and when will return flow bring it back into the area? Is there enough lingering moisture to keep orographic showers going into the weekend? Stay tuned!

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 541 PM MDT Wed Jul 22 2026

Widespread showers and thunderstorms will continue this evening. Terminals will be subject to breakpoint conditions through the evening and into the early morning hours of Thursday morning. Primary impacts will be lightning and heavy rain causing visibility and ceiling reductions. Showers will taper significantly after midnight, but non zero chances remain until near daybreak for most locations. Showers and thunderstorms will redevelop Thursday and include similar impacts as today.

HYDROLOGY

Issued at 1148 AM MDT Tue Jul 21 2026

A rich plume of monsoonal moisture has become established across portions of eastern Utah and western Colorado. Scattered thunderstorms capable of producing heavy rain are expected to continue this afternoon into late evening hours. Rainfall rates of 2- 3 inches per hour will be possible with the stronger storms. These rates could lead to flash flooding and debris flows especially over steep terrain and recent burn scars. Also, rain over the past several days has lead to saturated soils, which increase the chances for excessive runoff.

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 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...Flood Watch until 3 AM MDT Thursday for COZ001>014-017>023. UT...Flood Watch until 3 AM MDT Thursday for UTZ022>025-027>029.