509 FXUS65 KFGZ 192318 AFDFGZArea Forecast Discussion National Weather Service Flagstaff AZ 418 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...Saturday 20/00Z through Sunday 21/00Z...Mainly VFR expected. ISO-SCT SHRA/TSRA through 02Z, then clearing overnight. Brief MVFR or lower conditions and gusty, erratic winds possible in and near TS. S-SW winds 5-15 kts becoming light and variable overnight. SW winds 10-20 kts return after 18Z/Sat.
OUTLOOK...Sunday 21/00Z through Tuesday 23/00Z...Mainly VFR expected. ISO -SHRA/-TSRA mainly south of a KCMR-KFLG-KRQE line each afternoon/evening. Brief MVFR or lower conditions and gusty, erratic winds possible in and near TS. Daytime winds SW-W at 5-15 kts, becoming light and variable each night.
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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...Meola FIRE WEATHER...Peterson
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NWS FGZ Office Area Forecast Discussion