textproduct: Grand Junction

KEY MESSAGES

- There is a chance for strong storms over the next few days, capable of producing hail, gusty winds, and heavy rainfall.

- Moderate to heavy rainfall could lead to localized flash flooding, rockfalls, and mudslides at times this week.

- Temperatures return to near-normal through the week.

DISCUSSION

Issued at 1246 PM MDT Mon Sep 14 2026

High pressure anchored over the southeast CONUS will continue to block eastward progression of the troughing over the West this week. A resident jet streak will continue to provide upper level support for shower and storm development. Moisture supplies become the pivotal variable in the equation as the week progresses. The CWA remains under a marginal risk for excessive rainfall as well. With the lower atmosphere sufficiently moist, storms should have no problem producing measurable rainfall this week. This will continue to pose a flash flood risk around the region. Guidance continues to suggest the best moisture will focus on the Four Corners region, holding south of I-70.

This afternoon, storms will continue to take advantage of the overhead jet, which was sampled well on the morning Grand Junction sounding. Convective parameters remain bullish on the sounding too. Storms have been training southwest to northeast thus far today. Flash flood prone locales will remain a concern should we see sufficient storm training this afternoon and this evening. Hi res models are keeping shower activity lively again through the overnight hours. With little opportunity to dry back out, Tuesday will see the return of flash flooding risk. High pressure nudges back westward, allowing some richer subtropical moisture to get entrained into the upper level flow on Tuesday afternoon. Much of southeast UT and southwest CO get upgraded into a Slight Risk area for flash flooding on Tuesday.

The synoptic pattern sees little change as the week progresses. Subtropical moisture remains persistent and forcing aloft will sustain thunderstorms each day. The flash flood risk remains in play Wednesday and Thursday, as we never really dry out. On Friday, models are trying to eject the low out of the PACNW, with a transitional ridge behind it perhaps drying us out a smidge...or at least suppressing the subtropical moisture tap enough to limit rainfall. Forecast confidence wanes rather quickly this weekend, as models are trying to grapple with the pattern shift. While it does look like moisture does contract, the upper level pattern looks busy enough to keep some orographic showers present through the extended period of this forecast. With the Vernal Equinox approaching quickly and daylight fading, it seems apropos to discuss fall weather.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 529 PM MDT Mon Sep 14 2026

Scattered showers and thunderstorms continue today and tomorrow afternoon with lighter showers expected overnight. Gusty winds and light to moderate rainfall are the main hazards. Locally heavier rainfall may decrease vis to MVFR at some locations, though certainty on where this will occur has led to decreased visibility being left out of all TAF's. Cigs may fall below ILS breakpoints as storms pass by, particularly at ASE, EGE, and RIL.

GJT WATCHES/WARNINGS/ADVISORIES

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