textproduct: NWS Flagstaff

SYNOPSIS

For most, mainly hot and dry conditions are expected through the end of this week. Daily chances for afternoon showers and thunderstorms continue over portions of eastern and central Arizona each day, but especially Tuesday and Wednesday. After some drying Thursday and Friday, moisture begins to ramp up this weekend and into next week. Dangerous heat is expected at the lower elevations of the Grand Canyon through at least Saturday.

DISCUSSION

Moisture continues to increase across Arizona tonight as a favorable flow pattern persists along the New Mexico border. There are two mechanisms for moisture advection at this point, the deep and layered southerly-southwesterly flow and outflow boundaries that drive westward each evening. This will bring another active day for Tuesday east of the I-17 corridor, with some storms creeping as far west as Flagstaff/Payson late in the day. This pattern repeats Wednesday and may even make another push westward, although drier westerly flow aloft is developing at the same time.

By Thursday and Friday, the ridge collapses a bit and steering flow pushes some of the moisture pool temporarily south of our CWA, with maybe the only activity over the White Mountains.

By Saturday and Sunday, the ridge rapidly rebounds, strengthens and then moves into a very favorable flow pattern for the North American Monsoon. This is starting to look like our official start, as next week is looking robust.

As the moisture pool wobbles in and out of the CWA, we expect very warm temperatures to continue, possibly not peaking until Saturday. The Extreme Heat Warning for the Grand Canyon has been extended through this period, other lower elevations will experience similar conditions.

That is about it, moisture teases us for a few days and then, it surely looks like the Monsoon begins. Stay tuned!

AVIATION...Tuesday 07/18Z through Wednesday 08/18Z

Primarily VFR conditions. ISOLD SHRA/TSRA east of a KGCN-KFLG-KPAN line, becoming SCT in southern Apache and Navajo counties during the afternoon. Brief MVFR possible in storms. Winds are SW 10-20 kts through 03Z, becoming light and VRB overnight. Gusty and erratic winds expected near storms.

OUTLOOK...Wednesday 08/18Z through Friday 10/18Z...Primarily VFR conditions. SCT SHRA/TSRA primarily over southern Apache and Navajo counties on Wednesday afternoon, with ISOLD coverage as far west as a KFLG/KPAN line. ISOLD storms possible INVOF the White Mountains on Thursday afternoon. Winds are SW-W 10-20 kts each afternoon. Gusty and erratic winds expected near storms.

FIRE WEATHER...Tuesday and Wednesday

Most areas will remain 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 eastern Arizona, possibly generating isolated activity as far west as a Flagstaff to Payson line each afternoon. Stronger storms will be capable of producing wetting rains.

Thursday through Saturday...Hot and mostly dry. Chances for afternoon showers and thunderstorms continue over or just south of the White Mountains Thursday and Friday, activity starts moving back west and north Saturday. Expect daily southwesterly breezes from 10 to 20 mph, gusting from 25 to 30 mph.

FGZ WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning until 8 PM MST Saturday for AZZ006.