A low pressure system with multiple embedded disturbances moved across Arizona with scattered showers and thunderstorms. Some of these storms produced heavy rain and flash flooding.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS FGZ wrote it up.
A low pressure system with multiple embedded disturbances moved across Arizona with scattered showers and thunderstorms. Some of these storms produced heavy rain and flash flooding.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Flagstaff, AZ wrote its last area forecast discussion before the first event at Sep 26, 3:38 AM MST, 4 hours 37 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 338 AM MST Sun Sep 26 2021 .SYNOPSIS...Cooling daytime temperatures and increased shower and thunderstorm activity are expected Sunday, as low pressure impacts the region. Unsettled weather looks to continue for much of next week, with breezy and cooler conditions, as well as continued chances for showers and thunderstorms each day. && .DISCUSSION...Showers and thunderstorms are ongoing across portions of Navajo, Apache, and Gila counties this morning as the low has begun to shift northward. Amounts have generally been light but with the shift north and west a few embedded thunderstorms have developed which are likely producing locally heavier amounts. Expect the current band of showers and thunderstorms to continue to move northwest through the morning. Behind the morning band of showers and storms, redevelopment of showers and thunderstorms will be possible. Hi-res guidance appears to be struggling to catch up with many of them advertising a much weaker band of early morning showers in runs earlier this morning. A concern moving into the afternoon will be what the recovery of instability will be. A shield of midlevel clouds is currently in place across the area. Mid level water vapor does show some drier air coming in from the south that may help aid is reducing cloud cover by the afternoon. If this can occur, we could see a few stronger storms develop with the potential for flash flooding, gusty winds, and small hail. SPC has highlighted the far southern portion of Apache/Gila counties in a Marginal Risk of severe storms. As the low continues to track across Arizona, it appears the best dynamics will remain to our south which is why we are located on the far northern fringe of the Marginal area. As the low continues to move into New Mexico on Monday, expect shower and thunderstorms to continue mainly along the high terrain. A stormy pattern looks to continue for the remainder of the week as moisture remains in place and impulses continue to move through. By the end of the week, a new low still looks to cut off and move across Arizona. The track of this feature continues to be low confidence with some solutitons bringing this a bit further south than previous runs. Confidence remains only in daily shower and thunderstorm chances continuing with temperatures remaining cool and at or below normal. && .AVIATION...For the 12Z package...Expect mainly VFR conditions for the 24 hour TAF forecast period. Scattered -SHRA/TSRA and ISOLD +TSRA to become more widespread today. Heavier precipitation may produce occasional MVFR conditions. SFC winds generally light, except near convective activity and outflow boundaries. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Showers and thunderstorm coverage will increase today and Monday, with much cooler temperatures. Main threats will be periods of brief, heavy rainfall on area fire scars, as well as gusty outflow winds. Tuesday through Thursday...Below average daytime temperatures and daily chances for showers and thunderstorms throughout the period. Afternoon winds become breezy Tuesday and Wednesday, with a return to lighter winds on Thursday. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...ET AVIATION...MAS FIRE WEATHER...MAS For Northern Arizona weather information visit weather.gov/flagstaff
The Flagstaff radar (KFSX), 53 km away, was scanning. The volume nearest the first event began at 15:14 UTC.
4 flash flood. Local standard time, as filed.
Jacks Canyon Creek near Winslow rose 2.8 feet in 90 minutes from 2.2 feet to 5 feet at 945 AM.
Heavy rain caused Dry Beaver Creek to rise 3.6 feet in 30 minutes cresting at 1215 PM.
A 3.9 foot rise was recorded on the Agua Fria River (AFMA3) east of Cordes Junction.
Kaibab National Forest reported that flooding closed Forest Road 22 from Forest Road 422A to Big Springs.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2021Every state in 2021This day in weather historyWarnings in Arizona, September 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 986775, 986780, 986784, 986785.