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 /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 543 PM MDT Wed Aug 26 2026

Isolated to scattered showers and storms will continue through about sunset before dissipating, with better chances of convection impacting KTEX and KDRO where TEMPO groups are in place through 03Z. PROB30 groups are in place through 03Z for KGUC, KCNY and KVEL as storms are distant but close enough that there is low probability of impacts. Mainly expect gusty outflow winds to 35 kts with any convection and brief MVFR due to rain. Outside of convection, winds remain light with occasional breezes. Light, terrain driven winds return after sunset and overnight with breezy afternoon winds on Thursday and isolated convection over the high terrain.

GJT WATCHES/WARNINGS/ADVISORIES

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