Area Forecast Discussion
Issued by NWS Flagstaff, AZ
Issued by NWS Flagstaff, AZ
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034 FXUS65 KFGZ 201857 AFDFGZ Area Forecast Discussion National Weather Service Flagstaff AZ 1139 AM MST Thu Jun 20 2024 .SYNOPSIS...Daily chances for showers and thunderstorms are forecast through the weekend and into early next week, along with warming temperatures. && .DISCUSSION...Moisture from what is now Tropical Depression Alberto, currently located over central Mexico, has pushed across the eastern third of Arizona. The deepest moisture and most unstable air mass according to model soundings will be along and north of a line extending from Heber to Show Low to Springerville and includes the Chuska Mountains, Defiance Plateau and the Chinle Valley. Storms today will move generally from south to north and will be capable of producing 0.50 to 1.00 inch downpours, wind gusts in excess of 50 mph and localized storm runoff. The western boundary of the moisture extends as far west as Flagstaff and Page but a mid-level cap of relatively warm air will likely result in extremely isolated storms that far west. Shower storm activity will continue overnight but gradually diminish in coverage and intensity. On Friday...Moisture from Alberto spreads further north and west with at least a slight chance of showers even across our lower elevations locations of Bagdad and Black Canyon City. Elsewhere, deep moisture and unstable lapse rates will result in a good chance of showers and thunderstorm especially during the afternoon with daytime heating. Activity will diminish but likely not end overnight. For Saturday into Tuesday...High pressure expands across Arizona. The flow around the high will phase will the remnants of Alberto to the south to induce our first surge of moisture from over the Gulf of California. The onset of deep easterly flow over Mexico and the predominate flow being from sea to land with daytime heating indicates that our first monsoon pattern of the year will set upon us. Look for daily chances for showers and storms with day-to-day variations in storm intensity and coverage. Decent rainfall accumulations will be observed during this period exactly where is part of the mystery of the monsoon. From Wednesday onward...A drying trough from the west will push monsoon moisture eastward taking most of northern Arizona out of the action. However, moisture will likely linger in the vicinity of the eastern Mogollon Rim and White mountains for a continued shower and storm threat. && .AVIATION...Thursday 20/18Z through Friday 21/18Z...Mainly VFR conditions persist through the TAF period with FEW-BKN cloud cover after 19Z. Expect isolated to scattered -SHRA/-TSRA from 20Z-03Z with brief periods of MVFR VIS and CIGS, confined along and east of a KGCN-KFLG-KPAN line. Showers and BKN clouds look to continue through the night near the Four Corners region. Anticipate south-southwest winds, 20-30 kts, becoming south 5-15 kts after 03Z. OUTLOOK...Friday 21/18Z through Sunday 23/18Z...Another round of scattered to widespread -SHRA/-TSRA is expected on Friday from 19Z-03Z with showers continuing into the night. Greatest coverage will likely be along the Utah and New Mexico borders. Moderate chances for -SHRA/-TSRA continue through the weekend across all of northern Arizona. Anticipate enhanced south to southwest winds on Friday afternoon, 20-30 kts, becoming much lighter for Saturday and Sunday, outside of any gusty outflows from storms. && .FIRE WEATHER...Friday and Saturday...With moisture increasing into the weekend, expect rounds of scattered to widespread showers and thunderstorms each afternoon. Wetting rains (>0.10") are likely with any storms as well as gusty and erratic outflow winds up to 40 mph. Showers could continue overnight with good humidity recovery. Outside of any outflow winds, anticipate enhanced south to southwest winds, 25 to 35 mph, on Friday followed by much lighter southerly winds, 10 to 15 mph, on Saturday. Sunday through Tuesday...The active monsoonal pattern persists through Monday with 40 to 60% chances for showers and thunderstorms along and south of the Mogollon Rim and White Mountains. By Tuesday, chances decrease, however, isolated to scattered activity is forecast at this time, mainly along the higher terrain. Temperatures remain seasonal throughout this time with light southwesterly flow, 10 to 15 mph, each afternoon. && .FGZ WATCHES/WARNINGS/ADVISORIES...None. && $$ PUBLIC...McCollum AVIATION...LaGuardia FIRE WEATHER...LaGuardia For Northern Arizona weather information visit weather.gov/flagstaff