textproduct: NWS Flagstaff

SYNOPSIS

Windy and cooler conditions will continue today and Friday with an upper-level low approaching from the west. Isolated thunderstorms will be possible Friday afternoon in northern Coconino County as the low swings through. Critical fire weather conditions will also continue over portions of northeastern Arizona through Friday. Warmer conditions and lighter winds return over the weekend.

DISCUSSION

A deep upper low (for late May) is centered near the Bay Area this afternoon. The low will move eastward through Nevada and into Utah by Friday afternoon. Ahead of the low, gusty south to southwest winds will persist. Expect wind speeds of 15-25 mph with gusts 30-40 mph this afternoon. Most areas will see decreasing winds overnight, though a band of higher winds will persist just north of the Mogollon Rim/White Mtns where gusts over 30 mph should continue. Friday - the low moves closer to Arizona, bringing an increase in southwest winds. Gusts of 35-45 mph are forecast, and a Wind Advisory has been issued from 11 AM to 8 PM MST (Noon to 9 PM Navajo Nation) from the Mogollon Rim/White Mtns northward. Moisture and instability increase in northern Coconino County Friday afternoon, closest to the low. Some isolated shower or thunderstorm activity may develop, with current PoPs at 30-40% for the Kaibab Plateau and around 10-20% for the Grand Canyon and Page areas. This activity will end by early evening as drier air moves in. High temperatures will stay below normal today through Friday, with highs 10-15 degrees below normal on Friday.

Saturday into the middle of next week - heights will rise as the low moves east of the state. This will lead to gradually warmer daytime temperatures, reaching slightly above normal by early next week. However, with dry air in place, some freezing temperatures are likely at the usual high elevation cold spots (Bellemont, Tusayan, parts of Flagstaff) by Saturday and Sunday mornings. Ensemble data continues to show increasing precipitable water values from the east/southeast as early as Tuesday near the White Mountains and then farther west to around Flagstaff by mid week. Shower and thunderstorm chances are generally 10-30%, a bit higher around the White Mountains.

AVIATION...Thursday 28/18Z through Friday 29/18Z

VFR conditions, no precipitation expected. Winds S-SW 15-25kts, gusts 30-40kts daytime, S-SW 5-15kts overnight.

OUTLOOK...Friday 29/18Z through Sunday 31/18Z...VFR conditions, no precipitation expected. Winds S-SW 15-25kts, gusts 30-40kts daytime Friday, SW-W 10-20kts Saturday.

FIRE WEATHER...Friday and Saturday

Near-critical to critical fire weather conditions expected Friday, a Red Flag Warning is in effect for most of northeastern Arizona Friday afternoon. Temperatures relatively cool on Friday at about 5-10 degrees below average warm up closer to average on Saturday. Winds S-SW 15-25 mph, gusts 30-45 mph Friday, SW-W 10-20 mph on Saturday. Minimum afternoon RH 10-25% on Friday, 10-20% on Saturday.

Sunday through Tuesday....Dry conditions with temperatures near average on Sunday, warming to 5 degrees above average Monday and Tuesday. Winds SW-NW 5-15 mph Sunday, SW 5-15 mph Monday, SW-W 5-15 mph on Tuesday. Minimum afternoon RH 5-15% each day.

FGZ WATCHES/WARNINGS/ADVISORIES

Red Flag Warning from 11 AM MST /noon MDT/ to 8 PM MST /9 PM MDT/ Friday for AZZ109>114-139-140.

Wind Advisory from 11 AM MST /noon MDT/ to 7 PM MST /8 PM MDT/ Friday for AZZ009>017-039-040.

Red Flag Warning until 8 PM MST /9 PM MDT/ this evening for AZZ112>114-140.