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 drying trend is expected next weekend with some fire weather concerns becoming a possibility.

DISCUSSION

Seasonably strong high pressure centered over the New Mexico/Arizona/Mexico border area builds in this week bringing above normal temperature, especially the first part of the week. Expect temperatures to climb to about 10 degrees above average with high temperatures Monday through Wednesday in the upper 80s/low 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 Monday and Tuesday with an extension into Wednesday possible. Winds will be light out of the southwest at 5-15 mph.

An increase in moisture around the return flow of the high begins potentially as soon as Tuesday afternoon, lasting through Wednesday and Thursday. This could lead to 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. 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 to 40 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...Sunday 21/18Z through Monday 22/18Z

VFR conditions expected. Minor HZ/FU impacts possible near KFLG during the daytime and near KSEZ during the early morning hours due to a local wildfire. W-SW winds 10-15 kts with gusts around 20 kts, becoming light and variable overnight.

OUTLOOK...Monday 22/18Z through Wednesday 24/18Z...Mainly VFR conditions expected. Periods of HZ/FU possible near KFLG during the afternoon, becoming focused over KSEZ overnight due to a local wildfire. S-W winds 10-20 kts with gusts around 25 kts forecast each afternoon, becoming light and variable overnight. Isolated TSRA Tuesday afternoon along/north of a KFLG-KSOW line. Gusty and erratic winds to 40 kts possible with storms.

FIRE WEATHER...Monday and Tuesday

Breezy conditions will bring areas of elevated fire weather. Very dry on Monday with a slight increase in moisture Tuesday. Slight chance of thunderstorms (10- 20%) Tuesday afternoon, bringing gusty/erratic winds. Winds will generally be southwest to west 10-20 mph with gusts around 25 mph. Above normal temperatures persist with minimum RH 4-10% Monday, increasing to 10-20% Tuesday.

Wednesday through Friday...Continued very warm Wednesday, then slightly cooler. 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 up to 35 mph Friday. Minimum RH 12-25%. Near- critical fire weather by Friday, with a chance for critical fire weather persisting into the weekend.

FGZ WATCHES/WARNINGS/ADVISORIES

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