textproduct: NWS Flagstaff

SYNOPSIS

Low-grade monsoonal conditions today through at least Friday will lead to hot and drier conditions. Isolated to scattered showers and thunderstorms will develop along the higher terrain each afternoon and evening. Moisture will start to return this weekend, bringing back moderate monsoon activity.

DISCUSSION

The center of the high pressure at 500 mb is now over the New Mexico/Arizona border and will continue to wobble westward slightly through Friday. This setup will support low- grade monsoon activity as subtropical moisture is prevented from moving into northern AZ and the potential for a cap to develop. 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 will be the primary concern. The lower elevations of the Grand Canyon and the lower elevations of Yavapai county will have Extreme Heat Warnings in effect today through Friday evening.

For Saturday through Tuesday, long term ensemble guidance support that 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 30-70% chance of precipitation across most of northern AZ each day. This could support scattered to numerous showers and thunderstorms. There is still plenty of room for the details to change, and we will be watching this period closely with future forecast updates.

AVIATION...Wednesday 26/12Z through Thursday 27/12Z

VFR conditions, brief MVFR possible in storms. A few isolated to scattered showers/storms possible over the Rim and White Mountains between 18Z-02Z. Winds southwest to west 5-15 kts during the daytime, then light and variable or terrain driven overnight. Gusty and erratic winds possible near storms.

OUTLOOK...Thursday 27/12Z through Saturday 29/12Z...Mainly VFR conditions, brief MVFR possible near storms. Afternoon showers/storms possible over the higher terrain between 18Z and 03Z each day. Daytime winds SW-W 5-15kts, nighttime winds light and variable or terrain driven. Gusty and erratic winds possible near storms.

FIRE WEATHER...Today through Thursday

Warmer and drier conditions, with 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 through Friday. Isolated showers and thunderstorms mainly across the higher terrain Friday, increasing in coverage on Saturday and Sunday. Increase in showers and thunderstorms will cause max high temps to be closer to normal. 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 this morning to 8 PM MST Friday for AZZ006-037.