textproduct: Grand Junction

KEY MESSAGES

- Monsoonal moisture in place will keep scattered shower and thunderstorm chances in the forecast today.

- Heavier rainfall could lead to localized flash flooding over burn scars and susceptible terrain.

- Temperatures near to around 5 degrees above normal are expected through early next week, followed by a gradual warmup to close to 10 degrees above normal.

DISCUSSION

Issued at 1031 PM MDT Sat Aug 22 2026

As the Pacific Northwest trough tracks into Canada, the high centered over the Southern Plains starts to drift back toward the west. As a result, flow aloft shifts from southwesterly to more zonal Sunday, shifting the moisture plume north and east of the region. The best moisture will remain pooled along the Divide, and lingering across northeast Utah and northwest Colorado. Instability will be plentiful, provided morning cloud cover clears early enough. The one thing that will be lacking is upper level support, as the shortwave from today will be well to the east. Instead, orographic forcing will be the primary trigger for afternoon convection, with showers and storms firing off the terrain in the early afternoon. This activity will move off the terrain and over adjacent valleys through the afternoon and evening, but will likely not be as long- lasting as convection this afternoon. Heavy rain remains a concern, as surface levels remain well saturated and mixing ratios of 5-7 g/kg remain. This will keep flash flood and debris flow concerns for sensitive areas, including recent burn scars.

Above normal moisture sticks around through the coming week, as the high gradually shifts back into the Desert Southwest. Forcing will be somewhat lacking, with only the occasional shortwave rotating around the periphery of the high. This means that most afternoons will see isolated to scattered showers and thunderstorms develop over the higher terrain, with occasional periods of more focus convection coinciding with a passing wave. So long as surface levels remain saturated, heavy rain and flash flooding will remain concerns, particularly for sensitive areas. Additionally, gusty outflow winds and lightning will be daily threats. Temperatures will start around 5 degrees above normal, but will gradually warm through the week under the influence of the high. By the end of the coming workweek, look for highs to be 5-10 degrees above normal.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1129 PM MDT Sat Aug 22 2026

Isolated showers are diminishing across the region through the overnight with occasional lightning along the southwest faces of the southern mountains of southwestern Colorado and southeastern Utah. Expect a few lingering showers to last past 12Z. Look for convective activity to pickup again around 18Z over the higher terrain becoming scattered to widespread through 00Z when they will begin to diminish. These showers and thunderstorms are capable of producing gusty, erratic outflow winds, frequent lightning, and brief heavy rain leading to brief periods of MVFR/IFR conditions. Otherwise, winds will be generally light and terrain driven, with high level clouds and VFR conditions through the TAF period.

GJT WATCHES/WARNINGS/ADVISORIES

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