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 portions of eastern and central Arizona Wednesday, but expect less activity Thursday and Friday. Then, Monsoonal 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

The ridge axis that has been along the AZ/NM border for the last few days has started to flatten and retrograde to the west this morning. Before this fully develops, expect another day of scattered showers and thunderstorms over southern Navajo and Apache counties, as well as northern Gila County and possibly eastern Yavapai and southern Coconino counties.

Moisture values are decent over much of the CWA, but the deepest moisture still resides south of the Mogollon Rim and across much of southeastern Arizona. Any convection moving into this air mass this afternoon could develop into isolated, yet fairly strong storms.

By Thursday and Friday, the ridge position to our west will drive most moisture south of the CWA, with the only activity likely being over or just south of the White Mountains. This will be short-lived.

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 all of next week is now looking quite robust.

As the moisture pool wobbles in and out of the CWA, we expect very warm temperatures to continue, possibly not peaking until Saturday or Sunday. The Extreme Heat Warning for the Grand Canyon is in effect through Saturday evening. Other lower elevations will experience similar conditions, but are not in any EHW products.

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

AVIATION...Wednesday 08/12Z through Thursday 09/12Z

Expect mainly VFR conditions. SCT SHRA/TSRA, primarily over southern Apache and Navajo counties during the afternoon, may produce brief MVFR. Some ISOLD cells may push as far west as a KFLG/KPAN line by late afternoon. Daytime sfc winds SW10-20g25kts.

OUTLOOK...Thursday 09/12Z through Saturday 11/12Z...Expect mainly VFR conditions, as activity moves south. ISOLD storms possible INVOF the White Mtns each afternoon. Daytime sfc winds SW10-20g25kts.

FIRE WEATHER...Wednesday and Thursday

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 Wednesday, with more isolated activity as far west as a Flagstaff to Payson line. Thunderstorm activity Thursday mainly over the White Mountains. Stronger storms either day will be capable of producing wetting rains.

Friday through Sunday...Hot and mostly dry. Slight chances for afternoon showers and thunderstorms in the White Mountain region on Friday, before activity starts moving back west and north Saturday and especially Sunday. Expect southwesterly breezes from 10 to 20 mph, gusting from 25 to 30 mph on Friday. Winds becoming lighter and more variable for Saturday and Sunday.

FGZ WATCHES/WARNINGS/ADVISORIES

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