Area Forecast Discussion
Issued by NWS Flagstaff, AZ
Issued by NWS Flagstaff, AZ
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867 FXUS65 KFGZ 202036 AFDFGZ Area Forecast Discussion National Weather Service Flagstaff AZ 136 PM MST Fri Sep 20 2024 .SYNOPSIS...A low pressure system moving across Arizona will bring cooler temperatures, breezy winds, and chances for showers and thunderstorms tonight through Saturday. Warmer and drier weather is expected to return for much of the upcoming week. && .DISCUSSION...An upper level closed low is near San Diego this afternoon with showers and thunderstorms developing across southern California and Nevada. The low will gradually move east into Arizona tonight, and then northeast across the state on Saturday before exiting Saturday evening. We still expect scattered showers and thunderstorms to develop, mostly from late tonight through midday Saturday. Although a few isolated showers or storms are possible across western Arizona this afternoon, the bulk of the activity is expected to develop late tonight (after 10 pm MST). High resolution models are in pretty good agreement with a band of convection developing over Mohave/Yavapai Counties and spreading northeastward through the overnight hours. The best wind shear profiles still look to proceed the convection, so we expect only a minimal threat for a few isolated strong/severe storms. Light precipitation amounts are expected, from a few hundredths of an inch up to ~0.25 inches. Isolated heavy rain is possible, but any flood threat is low. On Saturday, the low is expected to be centered over central Arizona in the morning and track northeast through the day. Most shower/thunderstorm activity is expected to occur along and north of the Mogollon Rim. Overall, we`ve seen a continued slight increase in precipitation chances with chances extending a bit longer on Saturday along the Mogollon Rim. Another result of the trough will be colder temperatures Saturday, which have continued to trend a bit cooler and will be the coldest yet this season. Also notable is the possibility of some very light snow above 10,000 ft over the San Francisco Peaks. Dry conditions return Saturday evening when the low and trough axis move east of Arizona. A generally warmer and dry pattern is forecast from Sunday through next week while strong high pressure builds from the Pacific into the western states. The caveat is potential shortwave activity early/mid week. There is some ensemble support (about 30-40% of members), as well as previous operational model run support for a shortwave passing through the Rockies to drop as far west as Arizona and bring additional showers to the area. The majority of the guidance favors continued dry conditions, but something to keep an eye on for next week. && .AVIATION...Friday 20/18Z through Saturday 21/18Z...VFR conditions will prevail for most areas through 06Z. Expect south to southwest winds at 10-20 kts gusting to 20-30 kts through 01Z then diminishing. After 06Z, scattered -SHRA/-TSRA and MVFR conditions west of a KPRC-KPGA line after 06Z with chances gradually increasing and spreading eastward through 18Z. OUTLOOK...Saturday 21/18Z through Monday 23/18Z...Scattered -SHRA/-TSRA and MVFR conditions will continue during the day Saturday. Greatest chances will be along and east of a KPRC-KFLG- KPGA line. VFR conditions with clear skies return later Saturday night into Sunday. West-northwest winds at 10-20 kts on Saturday, then variable winds mostly 10 kts or less for Sunday and Monday. && .FIRE WEATHER...Saturday and Sunday...An area of low pressure will deliver chances for showers and thunderstorms on Saturday. Dry and warmer weather will move in on Sunday. Look for west-northwest winds at 10 to 20 mph on Saturday followed by northerly winds at 5 to 10 mph on Sunday. Monday through Wednesday...Warm and dry conditions will continue through Wednesday. Light and variable winds under 10 mph are forecast for Monday with northerly winds at 10-20 mph expected to develop on Tuesday and Wednesday. && .FGZ WATCHES/WARNINGS/ADVISORIES...None. && $$ PUBLIC...MCT AVIATION...McCollum FIRE WEATHER...McCollum For Northern Arizona weather information visit weather.gov/flagstaff