textproduct: Grand Junction

KEY MESSAGES

- Fire weather conditions remain localized on Sunday and into early next week. Fuels and surface conditions are still dry though. Obey all fire restrictions.

- Temperatures will remain above normal through the forecast with triple digits spreading across the lower desert valleys through late week and weekend period.

- Isolated showers and thunderstorms could return as early as tomorrow afternoon...with coverage increasing Monday and Tuesday.

- Chances for wetting rain remain low, instead gusty outflow winds and dry lightning poses a threat to new fire starts early next week.

DISCUSSION

Issued at 1040 PM MDT Sat Jul 4 2026

High pressure is centered over the Southern Rockies this evening squeezed between a trough digging downstream into the Midwest and an approaching upstream trough to the Cali coast. GOES ALPW shows a fetch of SubTrop moisture arriving with this trough while the 4 Corners region remains stuck under PWAT minimums. The KGJT RAOB at 05/00Z is near a quarter of an inch which is below the 10th percentile. As the westerlies retreat farther north ridge will be expanding northward and strong enough to force the upstream trough to trek across the western periphery of the Great Basin into the N.Rockies through Monday evening. The best moisture plume follows it...leaving us on the eastern edge with PWAT barely pushing above normal through mid week before drier air filters back in. With the best forcing and better moisture bypassing us it is hard to get excited about rain chances...in fact it seems more worrisome at this point. Potential vorticity fields suggest a weak wave moving across eastern Utah Monday morning and into Colorado during the afternoon. This may try and initiate weak convection but for the most part feel terrain forcing through the afternoon has a better chance of tapping into instability and popping some storms. It will likely take several generations and/or outflow boundary interactions to get meaningful storms going and decent precipitation to the ground. Unfortunately with dessicated vegetation and parched soil moisture conditions in this prolonged drought...sub cloud profiles suggest gusty winds and lightning will more of a threat than wetting rainfall. Dry thunderstorms and erratic winds near our active fires are likely going to be our focus each afternoon through Wednesday. The spine of the central and eastern San Juans remain the most probable area (~60%) to see a tenth of an inch during the peak in this moisture surge on Tuesday. By Wednesday the westerlies dip farther south as trough digs through the PacNW...effectively flattening the ridge and pushing back to the West. The results in drier air filtering back across the Intermountain West into our CWA which leaves the main thunderstorm chances to dwindle daily through the end over the week over the Colorado divide mountains. Hot and dry conditions settle in for the weekend.

Temperatures through this forecast period remain above normal reaching a peak as we head into next weekend when highs look well into the triple digits in the desert valleys. This time of year not a climatologically anomalous but we will could be floating around record territory for several days in a row. Most of the records at GJT are in the 103 to 105 range...except for the 107 set back in 2021 on the 9th. As mentioned before smoke conditions could have some impact under the heavier plumes. Night-time temperatures that have been cooling off nicely in this very dry pattern unfortunately will likely stay a bit warmer in the prolonged hot pattern.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 541 AM MDT Sun Jul 5 2026

Wildfire smoke will continue to reduce visibility at some locations throughout the next 24 hours. Otherwise, expect VFR conditions with light, terrain-driven winds.

FIRE WEATHER

Issued at 1040 PM MDT Sat Jul 4 2026

Critical fire weather conditions look to remain localized again on Sunday and into early next week. As we head farther into the week climbing temperatures and higher mixing could expand these conditions in some zones and this will continue to monitored daily for trends.

The region sees its first glimpse of notable moisture on Monday. The caveat appears to be that the bulk of this moisture lingers in the mid-level atmosphere. The initial push of moisture will creep in from the south on late Sunday. Inverted-V atmospheric profiles with relatively moist mid-layers could prompt some pyroconvection over hot spots Monday into Tuesday. Surface moisture lingers into Wednesday and peaks on Tuesday. Unfortunately this doesn't mean a whole lot as most valleys won't get much higher than 10-20% RH with any soothing RH values reserved for the higher elevations. As such, concerns are increasing that we could be facing another multi-day stretch of dry lightning focused around the slopes of the San Juans, albeit other locations across the CWA are poised for slight chances of thunderstorms as well (<35% chance). This will threaten new lightning ignitions and exacerbated wildfire conditions near virga showers and any gusty outflow winds that they produce.

To leave you off with a bit of good news though, beyond Wednesday spanning at least through the end of the work week, though RH falls off once again, the overarching upper-level pattern does not appear to become conducive to widespread critical fire weather conditions as flow remains on the weaker side. This pattern is relatively well-agreed upon amongst ensembles as well. Increasing heat and dryness will still likely pose some fire weather issues. Stay tuned for future forecast updates in case models begin to trend in another direction.

GJT WATCHES/WARNINGS/ADVISORIES

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