textproduct: Grand Junction

KEY MESSAGES

- Daily afternoon thunderstorm chances through the rest of this week, mainly on the higher terrain of western Colorado and eastern Utah.

- Localized heavy rainfall continues to pose a threat to flash flooding over burn scars and susceptible terrain.

- Daytime highs will run 5 to 10 degrees above normal through Friday, then near normal.

- Pattern shift this weekend brings cooler and wetter conditions Saturday and beyond.

DISCUSSION

Issued at 1251 PM MDT Wed Aug 26 2026

Some weak moisture continues to spill over the ridge this afternoon. Afternoon showers and thunderstorms will form on most terrain features today. Storms are moving east-southeast thus far and will continue this trajectory. While moisture sees a slight downturn this afternoon, there are still expectations for a few isolated showers to pose flash flooding risks, should they develop near susceptible washes, burn scars, and mountainsides. Showers will wane in the early evening hours and quiet conditions return overnight.

High pressure doesn't budge much Thursday and persistence will rule with terrain based showers and thunderstorms. Model guidance suggests additional moisture spilling over the ridge Thursday. Height falls precipitated by the inbound PACNW storm drive some additional forcing. This looks like potential for a few storms to extend their life cycle. Models hint at some overnight showers continuing too. Training storms and/or longer life cycles could produce some flash flooding again Thursday.

Pattern shift begins in earnest Friday with the ridge continuing to decay/push eastward. This will bring afternoon winds up in the southwesterly flow Friday and Saturday, including some localized critical fire weather conditions. Additional shower and thunderstorm activity can be expected Friday afternoon, as another pulse of moisture spills over the collapsing ridge. The northeast Pacific remains an active upstream impact to the pattern shift Saturday and beyond. A deeper pool of cooler, wetter air arrives Saturday. This, dare I say, looks more fall- like given the erosion of the monsoonal high pressure pattern. I'm sure we still have some warm days ahead of us, but this next week looks cooler and wetter. Tropical storm activity in the eastern Pacific could play into local moisture supplies later next week. This plays into September climatology and could supply some needed moisture to the West Slope...fingers crossed.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1144 AM MDT Wed Aug 26 2026

Isolated showers and thunderstorms will form over the higher terrain this afternoon with the best chances for convection over KGUC and KTEX. Outside of convection, generally light winds are expected. VFR conditions will continue, might be some brief MVFR under stronger showers/storms.

GJT WATCHES/WARNINGS/ADVISORIES

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