textproduct: Grand Junction

KEY MESSAGES

- Scattered storms will develop this afternoon with stronger storms capable of producing strong outflow winds, small hail, and localized heavy rainfall.

- The threat for localized flash flooding will be heightened today due to saturated soils and the potential for additional heavy rainfall.

- After decreasing precipitation chances this weekend, another push of monsoonal moisture arrives by Tuesday.

DISCUSSION

Issued at 1152 AM MDT Fri Sep 18 2026

ONE LAST RAINY DAY; DRYING OUT THIS WEEKEND:

A low pressure system will track across the Intermountain west over the next 24 hours which will break us out of the ongoing wet pattern. Until then, expect one last day of scattered to widespread showers and storms. Northeast Utah and northwest Colorado in particular could be the hot spot for stronger storms with stronger wind shear and instability expected. Isolated strong storms cannot be ruled out elsewhere. With stronger daytime heating expected today, storms will be capable of producing strong outflow winds, hail, and heavy rainfall. The threat for localized flash flooding will be heightened due to antecedent saturated soils and the potential for additional heavy rainfall.

By Saturday, the passage of a cold front will help scour some of the moisture from the region, but PWATs will remain around 150% percent of normal. This means that the storm coverage and the threat for heavy rainfall will decrease, but enough moisture remains in place to support isolated to scattered convection. Sunday looks drier yet with PWATs 75-125% of normal. However, we expect enough remnant moisture for isolated convection over the higher terrain.

MORE MONSOON NEXT WEEK:

The relatively dry period won't stick around for long as moisture- rich southwesterly flow kicks back in Monday PM into Tuesday. While the details could fluctuate between now and then with variance amongst and within ensemble families, the general thought is that wetter weather will return by Tuesday and could remain in place throughout the week. Early guidance supports wetter weather, especially south of I-70, but less widespread than we've experienced this week.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 528 PM MDT Fri Sep 18 2026

Showers and thunderstorms have mainly been impacting terminals along and north of I-70, and will continue to do so through 06Z. These storms have been capable of producing large hail and heavy rainfall. Activity will transition from convective to more stratiform showers after 06z, before clearing out after 12z. Winds will be generally light and variable through the period, influenced heavily by shower or storm activity. Gusty westerly winds will pick up tomorrow afternoon. VFR conditions will prevail, but drops to MVFR will be possible under intense storms. KASE/KRIL/KEGE will see periods of CIGS below ILS breakpoints this evening with passing showers.

GJT WATCHES/WARNINGS/ADVISORIES

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