textproduct: NWS Flagstaff

SYNOPSIS

Hot and drier conditions will return for much of the week with isolated showers and thunderstorms, mainly along the higher terrain each afternoon and evening. Moisture returns with moderate monsoon activity expected over the weekend.

DISCUSSION...Today

Today is setting up to be a slightly drier and less active day across northern AZ. Yesterday's surge in moisture from the Gulf of California into western and northwestern AZ has declined in magnitude as the high to our east wobbles and the flow turns suboptimal. PWAT values still range from near to slightly above normal for late August. And with clear skies this morning leading to unrestricted surface heating, some modest destabilization is still expected. Overall, expect isolated showers and thunderstorms mostly along the higher terrain today.

Wednesday through Friday...The high continues to wobble and slowly drift west, eventually becoming centered over northern AZ. This is typically a poor setup for monsoon activity because it prevents the deepest subtropical moisture from reaching northern AZ and can introduce a cap. The overall forecast reflects this idea, maintaining daily isolated to scattered showers and thunderstorms mostly along the high terrain. With the reduction in moisture and above normal heights at 500 mb, heat once again becomes a concern. The lower elevations of the Grand Canyon and the lower elevations of Yavapai county will have Extreme Heat Warnings in effect through this period.

Saturday through Monday...Long term ensemble guidance leans towards the high shifting back to the east, while a deep trough approaches from the west. This could be a fairly active setup, and the forecast calls for a 30-60% chance of precipitation across most of northern AZ each day. There is still plenty of room for the details to change, and we will be watching this period closely with future forecast updates.

AVIATION...Tuesday 25/18Z through Wednesday 26/18Z

Mainly VFR conditions. ISO SHRA/TSRA between 19Z-02Z, mainly across the higher terrain. Brief MVFR conditions and gusty/erratic winds to 40 kts possible in heavier SHRA/TSRA. Outside of storms, expect S-SW winds 5-15 kts, becoming variable or terrain driven winds overnight.

OUTLOOK...Wednesday 26/18Z through Friday 28/18Z...Mainly VFR conditions. ISO SHRA/TSRA between 18Z-02Z each day, mainly over the higher terrain. Brief MVFR conditions and gusty/erratic winds to 40 kts possible in heavier SHRA/TSRA. Outside of storms, expect SW-W winds 5-15 kts, becoming variable or terrain driven winds overnight.

FIRE WEATHER...Today through Thursday

Warmer and drier conditions expected. Isolated to scattered showers and thunderstorms along the higher terrain each afternoon. Outside of gusty and erratic storm driven winds, expect southwest to west winds around 5-15 mph during the day, becoming variable at night.

Friday through Sunday...Hot temperatures continue. Isolated showers and thunderstorms mainly across the higher terrain Friday, increasing in coverage on Saturday and Sunday. Outside of storms, expect southwest to west winds around 5-15 mph each afternoon, becoming variable at night.

FGZ WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning from 10 AM Wednesday to 8 PM MST Friday for AZZ006-037.