515 FXUS65 KFGZ 192114 AFDFGZArea Forecast Discussion National Weather Service Flagstaff AZ 215 PM MST Fri Sep 19 2025
.SYNOPSIS...Chances for showers and thunderstorms diminish over the weekend, especially Saturday, with a bit warmer temperatures. A new low pressure system forming near San Diego on Sunday will continue shower and thunderstorm chances into early next week.
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.DISCUSSION...Storm activity has actually decreased though the day as subsidence behind this mornings s/wv and a heavily rain-cooled air mass governed our convection. We expect activity to decrease fairly quickly tonight, as the flow aloft becomes anti-cyclonic and warms a bit.
Nonetheless, despite a less favorable environment Saturday, so much moisture is still around, we put isolated to scattered PoPs back into the forecast.
By Sunday and into early next week, it now looks like a closed low will form near San Diego. This will keep the moisture stream over Arizona for several more days, along with introducing some shear and cooler mid-level temperatures. We have begun increasing shower and thunderstorm chances as a result.
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.AVIATION...Friday 19/18Z through Saturday 20/18Z...Expect mainly VFR conditions. Areas SHRA/-TSRA could cause brief MVFR conditions through 02Z, then clearing. Sfc winds not expected to impact flight operations.
OUTLOOK...Saturday 20/18Z through Monday 22/18Z...Expect mainly VFR conditions. Isolated -SHRA/-TSRA from 19Z-02Z Saturday, mainly south of the I-40 corridor. Coverage potentially increasing during the daytime hours Sunday and Monday. Sfc winds not expected to impact flight operations.
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.FIRE WEATHER...Saturday and Sunday...Scattered showers and thunderstorms will diminish overnight as high pressure strengthens over the district. More isolated coverage, mainly south of I-40 is expected Saturday, with a slight increase for Sunday. Winds will mainly be light, trending southwest through west.
Monday through Wednesday...A chance of showers and thunderstorms will persist through the period, especially Monday, as a new low pressure system forms off the southern California coast. Winds will remain mainly light.
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.FGZ WATCHES/WARNINGS/ADVISORIES...None.
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PUBLIC...Peterson AVIATION...Peterson FIRE WEATHER...Peterson
For Northern Arizona weather information visit weather.gov/flagstaff
NWS FGZ Office Area Forecast Discussion