textproduct: Grand Junction

KEY MESSAGES

- Isolated afternoon showers and storms possible through Saturday.

- Precipitation chances increase throughout the holiday weekend, with peak coverage expected Sunday and Monday. Flash flooding will be the primary threat with periods of heavy rain possible.

DISCUSSION

Issued at 1115 AM MDT Fri Sep 4 2026

ISOLATED SHOWERS AND STORMS FRIDAY AND SATURDAY:

A weak jet accompanied by some modest moisture will nose into the Four Corners region tonight. Some of the hi-res models support the development of showers along the moisture transport gradient, especially in southern foothills of the San Juans. This moisture remains in place for much of Friday and Saturday, especially along the Divide. As a result, afternoon convection favoring the higher terrain will return to the forecast, but most locales will remain dry with seasonable temperatures and breezy afternoon winds.

MONSOONAL MOISTURE SURGES SUNDAY AND MONDAY:

A strong low pressure over the Pacific Northwest will advect a plume of anamolous moisture on Sunday and Monday. This could result in scattered to widespread convection across the region. PWATs upwards of 200% of normal will support the potential for heavy rainfall and flash flooding, especially around recent burn scars and areas with steep terrain. This threat is particularly heightened where soils have reached peak saturation after multiple rounds of storms this past week. Models are beginning to show that the peak moisture might be overnight Sunday. Also, attm on Sunday afternoon there is not much instability or it may be limited to a certain area. This will play a role in the coverage and intensity of showers and storms.

Beyond Monday the low pressure moves across the northern US causing high pressure to build over the region. The uncertainty is if we stay in the moist southwest flow. There is also signs of an active Pacific Northwest, which may too play a role in precipitation chances.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 544 PM MDT Fri Sep 4 2026

VFR conditions are forecast through the TAF period. A slight chance (10-15%) for showers and storms exist for the higher terrain areas for the next couple of hours. Wind speeds will begin to subside this evening before strengthening again tomorrow afternoon with periodic gusts up to 25 knots.

GJT WATCHES/WARNINGS/ADVISORIES

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