textproduct: NWS Flagstaff

SYNOPSIS

Above average temperatures expected for most of the week. Moisture starts moving in with thunderstorm chances beginning as soon as Tuesday, but better chances Wednesday and Thursday. A drier and windier trend is expected next weekend, elevating fire weather concerns.

DISCUSSION

Seasonably strong high pressure centered over the New Mexico/Arizona/Mexico border area builds in this week bringing above normal temperatures, especially the first half of the week. Expect temperatures to climb to about 10 degrees above average with high temperatures today through Wednesday in the upper 80s/lower 90s in the high country to near 110 at the bottom of the Grand Canyon and the low deserts of southern Yavapai County. An Extreme Heat Warning has been issued for the bottom of the Grand Canyon today and Tuesday with an extension into Wednesday possible.

An increase in moisture around the return flow of the high begins potentially as soon as Tuesday afternoon, lasting through Wednesday and Thursday. This presents a 10-20% chance of storms in the highest elevations as soon as Tuesday afternoon, with a 20-40% chance along the Rim and White Mountains by Wednesday with most of northern Arizona seeing a 20-50% chance of storms by Thursday as precipitable water increases to above 90th percentile of climatology. The extra moisture should start moderating the temperatures closer to normal Thursday afternoon.

By Friday, a trough moving across the northern tier will flatten the ridge and shut the monsoon moisture off for the weekend. It will also bring in much drier air and as the trough brushes by, elevated winds from the southwest between 20-30 mph, gusting up to 45 mph on Saturday and Sunday. If this forecast holds, a good chunk of the region will be under critical fire weather conditions, with fire weather products likely being issued as the week progresses.

AVIATION...Monday 22/12Z through Tuesday 23/12Z

VFR conditions. Winds are light and VRB through 18Z, becoming SW at 5-15 kts after 18Z. Localized wind gusts 20-25 kts possible throughout the afternoon. Light and VRB winds return after 03Z.

OUTLOOK...Tuesday 23/12Z through Thursday 25/12Z...Mainly VFR conditions expected. A 10-20% chance for SHRA/TSRA on Tuesday afternoon/evening primarily along and north of the Mogollon Rim, becoming a 20-40% chance on Wednesday afternoon/evening. Gusty and erratic winds expected near storms. Otherwise, daytime winds are W-SW 10-20 kts. Light and VRB or terrain driven forecast for the overnight periods.

FIRE WEATHER...Today and Tuesday

Breezy with areas of elevated fire weather. Very dry on Monday then an increase in moisture bringing a slight chance of thunderstorms (10-20%) Tuesday afternoon. Winds are southwest to west 10-20 mph with gusts around 25 mph each day, though gusty and erratic winds are expected near storms. Above normal temperatures persist with minimum RH 4-10% Monday, increasing to 10-20% Tuesday.

Wednesday through Friday...Continued very warm conditions on Wednesday, then slightly cooler thereafter. Breezy with increasing moisture and thunderstorm chances, peaking on Thursday at 20-50%. Southwest to west winds 10-20 mph with gusts around 25 mph Wednesday and Thursday, increasing to 15-25 mph with gusts to 35 mph Friday. Minimum RH 12-25%. Near-critical fire weather on Friday, with a chance for critical fire weather persisting into the weekend.

FGZ WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning from 10 AM this morning to 7 PM MST Tuesday for AZZ006.