textproduct: NWS Flagstaff

SYNOPSIS

For most, mainly hot and dry conditions are expected through the end of this week. Chances for afternoon showers and thunderstorms will continue over the White Mountain region Thursday and Friday. Monsoonal moisture begins to ramp up over this weekend and into next week, with storm activity pushing back west and north and becoming more frequent. Dangerous heat is expected at the lower elevations of the Grand Canyon and then Glen Canyon through at least Saturday.

DISCUSSION

Changes in steering flow and the influx of drier boundary layer air over the northern and western zones will lead to fairly quiet and hot conditions over the next 2 or 3 days. These changes are bring driven by a westward relocation and flattening of the ridge that is currently underway. Higher moisture values persist over western New Mexico and southeastern Arizona, meaning the White Mountains will not be fully overcome by these changes and convection will continue in this area. Most other locations will not see any convection for Thursday and Friday, perhaps even Saturday.

Over the weekend and into next week, the ridge recenters to our northeast and strengthens dramatically. This will open the door for the moisture pool that is already in place and Monsoon 2026 will begin in earnest by Sunday or Monday.

Due to the strength of this ridge, any location that does not see rainfall or enhanced cloud cover will still be quite warm, even for this time of year. EHW products for the Grand Canyon and Glen Canyon will persist through at least Saturday as a result. This is not to say that other lower elevation locations will not be uncomfortable at times, but overnight recovery and less potential for outdoor activity will temper the need for additional products.

By early next week, the aforementioned Monsoon 2026 should keep most locations at least 5-10 degrees cooler, likely eliminating the need for heat products.

AVIATION...Thursday 09/12Z through Friday 10/12Z

Expect mainly VFR conditions. ISOLD-SCT -SHRA/TSRA from 19Z-02Z INVOF the White Mountains. Daytime sfc winds SW10-20g25kts, light overnight.

OUTLOOK...Friday 10/12Z through Sunday 12/12Z...Mainly VFR conditions. ISOLD-SCT -SHRA/TSRA INVOF the White Mountains for Friday, spreading a bit further west and north on Saturday. Daytime sfc winds SW10-20kts Friday, light and variable for Saturday. Winds light overnight.

FIRE WEATHER...Thursday and Friday

Most areas will be hot and dry, with daily southwesterly breezes from 10 to 20 mph, gusting from 25 to 30 mph. Chances for showers and thunderstorms continue over the White Mountain region each afternoon, but convection outside of east-central Arizona is unlikely.

Saturday through Monday...Remaining hot, with isolated shower and thunderstorm activity on Saturday, then pushing west and north and becoming more frequent Sunday and Monday. Wetting rains are likely from convection by Sunday and Monday. Generally light and variable winds Saturday, remaining light, 5 to 15 mph, but trending southerly for Sunday and Monday.

FGZ WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning from 11 AM MST Saturday until 8 PM MST Sunday for AZZ005.

Extreme Heat Warning until 8 PM MST Sunday for AZZ006 below 4000 feet.