textproduct: Grand Junction

KEY MESSAGES

- Showers and thunderstorms increase in coverage on Tuesday and Wednesday, favoring the terrain.

- Chances for wetting rains remain low. Gusty outflow winds and dry lightning pose threats for new/existing wildfires.

- Localized critical fire weather conditions emerge Thursday for southeast UT and southwest CO.

- Afternoon highs 10-15 degrees above normal this weekend.

DISCUSSION

Issued at 1013 PM MDT Mon Jul 6 2026

STORMS TUESDAY:

We are firmly underneath the anticipated push of moisture making its way through the broad southwestern CONUS ridge. Per the 00Z GJT sounding, we have nearly tripled our PWAT's from 24 hours prior. The 0.7 inch PWAT seen today actually surpasses the climatological mean, so even though it's not impressive moisture by any means, it's refreshing nonetheless. To add, convection appeared to be limited and only a few lightning strikes were ultimately observed. In fact, the only location of frequent lightning was driven by the Babylon Fire itself.

As far as Tuesday is concerned, moisture continues to increase, and with it the chances of showers and thunderstorms. We were able to see sparse areas of wetting rain today across the southern CWA, so we know low-level conditions are capable of allowing rain to reach the ground in some locations, but we still anticipate the bulk of precipitation to evaporate before reaching the ground Tuesday. Higher elevations will still see the best opportunities for wetting rain though due to a bump in surface relative humidity to 20-40%. In these higher elevations, QPF is expected to generally fall below 0.15 inches, but a few localized higher amount cannot be ruled out with stronger storms, particularly near to the Divide around Highway 149. To note, should any heightened rainfall rates track over burn scars or active wildfires, localized flash flooding will be possible. The probability of this is low at this time, but it is important to be aware of conditions on Tuesday, especially if you are near these vulnerable areas.

Mild instability spreads out across virtually the entire CWA Tuesday as well according to CAM's, meaning the probability of thunderstorm development will be notably higher than what was seen on Monday. CAM's are consistent in the earliest onset of thunderstorms occurring between I-70 and US-40 around 11AM MDT before the southern portions of the region kick into action throughout the early afternoon.

TRANSITION INTO HOT AND DRY PATTERN:

Moisture holds on to a degree on Wednesday, but precipitation potential begins to drop off, and by Thursday, shower and thunderstorm chances become much more isolated. By Friday, models are in agreement that moisture will have been depleted and PWAT's re- establish at 50-80% of normal. As the southwestern CONUS high builds northwards and heats up the Intermountain West into the weekend, we will likely see afternoon highs reach 10-15 degrees above normal and most low- lying areas below 7000 feet peak in the triple digits.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 527 AM MDT Tue Jul 7 2026

Midlevel clouds are draped across much of the forecast this morning and will continue to drift eastward this morning. Convection will start around 17 to 18Z with some isolated showers and storms favoring the higher terrain. Did include KASE, KTEX, and KGUC in PROB30 groups to account for this possibility. Variable and gusty outflow winds will be the biggest concerns with any convection this afternoon. Some afternoon gusts of 20 to 25 kts can't be ruled out either. Despite all that, VFR conditions will continue for the next 24 hours.

FIRE WEATHER

Issued at 1013 PM MDT Mon Jul 6 2026

Monday, multiple wildfires across the CWA developed pyroconvective clouds as a result of the extremely dry surface conditions and increasing mid-level moisture. Minimal rain reached the surface in most areas around wildfires. Tuesday, region-wide moisture hits its peak for most locations across the region. Surface conditions, though expected to moisten a little, are still forecast to fall below 20% RH in low-lying areas. These relative humidities will struggle to support wetting rains. Higher elevations (generally above 8000 feet) should see afternoon RH rise above 20% and as high as 45% above some mountain passes. Still not ideal, but better for rainfall to reach the surface.

We didn't really see the dry thunderstorm threat manifest Monday, not because of ample rain, but because convection was generally weaker than expected. We are still confident that we will see more dry thunderstorm coverage on Tuesday though. CAM's are in agreement in placing much of the region under a more unstable atmosphere with CAPE generally spanning 300-500 J/kg. This should bolster convective development. In those low-lying areas with low RH, virga showers and isolated dry thunderstorms are likely to develop, bringing about a risk of new lightning ignitions and gusty outflow winds which could impact new and existing wildfires. Over the slightly moister higher elevations, wetting rain potential is up to 45-70% east of Highway 550 above Ouray (notable higher than 24 hours ago) with other locations across the San Juans, central Colorado mountains, Flat Tops, and eastern Uintas holding relatively steady at 25-40%. A few storms could be capable of producing localized heavy rainfall which, if they track of an active fire or burn scar, could prompt debris flow concerns. The probability of this remains low, but non- negligible.

Isolated dry thunderstorm concerns continue Wednesday and possibly into Thursday before storm potential almost entirely diminishes. As hotter and drier conditions settle in Friday and into the weekend, fire conditions could become exacerbated. High confidence in relatively mild winds should keep critical fire weather coverage on the more isolated end, generally favoring the Four Corners region.

GJT WATCHES/WARNINGS/ADVISORIES

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