textproduct: NWS Flagstaff

SYNOPSIS

Dry, breezy, and warm conditions are forecast for this weekend, with near-critical fire weather across portions of northern Arizona. Slight chance for showers and thunderstorms to return by the middle of next week.

DISCUSSION

A shortwave trough along the west coast will move eastward, passing north of the state on Saturday. This will cause the already breezy winds today to increase a bit more by Saturday. Saturday's winds are forecast to be southwesterly at 15-25 mph with gusts in the 30-35 mph range, strongest in northeast Arizona. Dewpoints are also forecast to crash during the afternoon, dropping relative humidities at or below 10% for all areas. A Red Flag Warning has been issued for parts of the Little Colorado River Valley and the Chuska Mtns/Defiance Plateau for Saturday where winds are expected to be strongest. Sunday and Monday - high pressure builds northward into Arizona, this will allow wind speeds to drop below critical fire weather criteria. Daytime temperatures will start to increase, reaching 5 degrees above normal by Monday. Highs at the lower elevations of Grand Canyon will approach Extreme Heat Warning criteria by Monday afternoon.

Tuesday through Thursday - high pressure is forecast to be centered near southeast Arizona, allowing for a moisture increase around the west side of the high. Mean precipitable water forecasts from the grand ensemble peak around 0.70"-0.90" Wednesday into Thursday. This will bring slight chances for showers and thunderstorms, mainly during the afternoon. PoP values are 10-25% at this time, highest along/north of the Mogollon Rim - watch for updates as we get closer to mid week. Otherwise, daytime temperatures will be 5-10 degrees above normal, with some localized Heat Risk values in the major category for the lower elevations of Yavapai County and around Page. Highs will also stay at or above warning criteria for the lower elevations of Grand Canyon. Breezy southwest to west winds are also expected mid to late week on the north side of the high.

AVIATION...Friday 19/18Z through Saturday 20/18Z

VFR conditions are expected to continue. Winds will be S/SW 10-20 kts with gusts up to 25-30 kts through about 03Z, and then decrease to between 5-10 kts overnight.

OUTLOOK...Saturday 20/18Z through Monday 22/18Z...Gusty SW winds continue through the weekend. On Saturday, winds becoming 15-20 kts with gusts near 30 kts 18Z - 03Z Sun. On Sunday, W/SW winds 10-15 kts with gusts to 20 kts. Winds decrease to between 5-10 kts during the overnight hours. VFR conditions are expected to continue.

FIRE WEATHER...Saturday and Sunday

A significant drying trend is underway and will bring areas of critical fire weather to northeastern Arizona on Saturday. Southwest winds increase Saturday to 15-25 mph with gusts of 30-35 mph across much of the high terrain from the Mogollon Rim northward. A Red Flag Warning has been issued for critical fire weather in far northeastern Arizona Saturday with near-critical fire weather elsewhere. Winds decrease a bit Sunday but conditions remain very dry and breezy.

Monday through Wednesday...Dry conditions will continue with low daytime humidity through Tuesday. Building high pressure will bring much warmer temperatures and lighter winds early next week. A gradual increase in moisture brings returning thunderstorm chances by Wednesday afternoon.

FGZ WATCHES/WARNINGS/ADVISORIES

Red Flag Warning from 11 AM MST /noon MDT/ to 6 PM MST /7 PM MDT/ Saturday for AZZ111-113-114.