Area Forecast Discussion
Issued by NWS Flagstaff, AZ
Issued by NWS Flagstaff, AZ
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017 FXUS65 KFGZ 210534 AFDFGZ Area Forecast Discussion National Weather Service Flagstaff AZ 1034 PM 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. && .UPDATE...The showers and thunderstorms today brought some much- welcomed precipitation to central and northern Arizona, with local accumulations of over 0.5"+ in the heavier storms. Several reports of small hail were also received this afternoon. Activity has decreased this evening, with the remaining scattered showers and thunderstorms moving northeast through Navajo and Apache Counties at this time. Most of the precipitation should dissipate or move out of Arizona by midnight. The current forecast is on track, and only minor updates were made this evening to account for the evolution of the storms this evening and overnight. Expect another round of thunderstorms tomorrow (most numerous along the Utah border), with more widespread storm coverage on Saturday. && .PREV DISCUSSION /450 PM MST/...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...Friday 21/06Z through Saturday 22/06Z...Only a few isolated showers expected overnight, with generally southerly winds decreasing to 5-15 mph most areas. Storms will develop again on Friday, with scattered to numerous storms along and near the Utah border after 18Z, with MVFR and local IFR conditions. Expect south to southwest winds on Friday 20-30kts, and gusty around thunderstorms. OUTLOOK...Saturday 22/06Z through Monday 24/06Z...Showers and thunderstorms will develop again on Saturday and Sunday (30-60% chance) with MVFR and local IFR conditions in the stronger 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...BAK/McCollum AVIATION...BAK FIRE WEATHER...BAK For Northern Arizona weather information visit weather.gov/flagstaff