textproduct: Grand Junction

KEY MESSAGES

- Look for widespread showers and thunderstorms Thursday as deep monsoonal moisture continues to flow into the region.

- Localized heavy rainfall may prompt flash flooding and debris flows, especially around burns scars.

- Shower and thunderstorm coverage decreases Friday into the weekend.

- Temperatures cool through the end of the work week, and start rebounding over the weekend.

DISCUSSION

Issued at 1101 PM MDT Wed Aug 12 2026

Models are in good agreement with satellite imagery with troughing along the West Coast and the high pushed off to the east over east Texas. This pattern puts eastern Utah and Western Colorado under a southwesterly flow pulling deep monsoonal moisture up out of Arizona with pwats running over an inch across the region.Between the cloud cover and evaporative cooling, temperatures were ten or more degrees cooler today than what we've been seeing for the last week or so. The limited heating did a lot to stifle convection. Tomorrow, Thursday, looks to be very similar to today with the deep moisture and heavy cloud cover, but the flow aloft increases some to provide weak but better upper-level dynamics to support stronger showers and thunderstorms Thursday into Friday morning. Guidance is calling for more widespread convective activity across the region. Concerns continue to be for areas of heavy rain and training showers and thunderstorms, especially over the recent fire scars where the risks for flash flooding and debris flows are a high threat. Be sure to check your forecast before going out, have a way for getting alerts and stay aware of your surroundings.

The continued southwesterly flow will tend to advect drier air into the region into the weekend. coverage of showers and thunderstorms will become more scattered Friday favoring the higher terrain across the region and more isolated over the weekend. Temperatures rebound five to ten degrees by next Monday, but there are hints of another surge of moisture early next week from some models while others have us return to a drier pattern. Hence, forecast confidence drops off beyond a few days as slight variations in the patterns can significantly change forecast outcomes.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1144 PM MDT Wed Aug 12 2026

Showers and thunderstorms continue across the region. Most of this activity south of I-70 will end over the next hour or two, but along the I-70 Mountain Corridor and north a wave of showers and thunderstorms will move through overnight. At 18Z widespread convective activity will begin again. Showers and storms could cause brief periods of MVFR conditions, but outside of this VFR conditions are expected to prevail. Winds will be light and variable at most sites overnight.

HYDROLOGY

Issued at 1152 AM MDT Wed Aug 12 2026

Moisture chances become more widespread, peaking in coverage Thursday. Model guidance suggests heavy rainfall from thunderstorms and/or training storms is possible through the afternoon and evening hours. With that being said, the Flood Watch runs until midnight tonight. Continue to stay weather aware and have multiple ways to receive watches and warnings.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Flood Watch until midnight MDT tonight for COZ018-019. UT...None.