Above normal precipitable water values, high surface dewpoints, and light southerly or southeasterly steering flow will continued across northern Arizona. The morning sounding showed moderate instability, with potential for back-building and/or training.
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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.
Above normal precipitable water values, high surface dewpoints, and light southerly or southeasterly steering flow will continued across northern Arizona. The morning sounding showed moderate instability, with potential for back-building and/or training. The Weather Prediction Center put northern Arizona in the slight risk categories and a Flash Flood Watch was issued for much of the CWA.
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 Aug 11, 10:00 AM MST, 3 hours 50 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 1000 AM MST Thu Aug 11 2022 .SYNOPSIS...Daily showers and thunderstorms will continue across much of northern Arizona at least through the end of the week and into the weekend. Scattered to widespread thunderstorms are likely each afternoon, with flash flooding being the main threat. && .DISCUSSION...Above normal PW values, high surface dewpoints and southerly or southeasterly steering flow will continue for the next several days. 12Z sounding again showing moderate instability, with some potential for back-building and/or training. Due to all these factors and agreement with WPC slight risk categories, we will be issuing a FFA for much of the CWA today and Friday. These updates will be out shortly. As far as the remainder of the forecast elements, the short term gridded products look reasonable and no further updates will be needed this morning. && .AVIATION...For the 18Z TAF package...Expect SCT-NMRS SHRA/TSRA and ISOLD +TSRA along and south of a KSJN-KFLG-KGCN line from 18Z-03Z. Activity more in the ISOLD-SCT range north of that line and AFT 03Z Friday. There is a possibility of a TSRA cluster this evening along or north of a KINW-KSJN line. Any heavier cells will produce brief MVFR/IFR. Sfc winds light. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...An active monsoonal pattern continues today and Friday, bringing with widespread shower and thunderstorm coverage. Main threats include flash flooding and gusty, erratic winds. Light winds expected outside of storms, with average temperatures. Saturday through Monday...Shower and thunderstorm chances remain high through the weekend and into next week. Winds will be light outside of storm activity, with seasonal temperatures. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...Peterson AVIATION...Peterson FIRE WEATHER...MAS/Peterson For Northern Arizona weather information visit weather.gov/flagstaff
The Cedar City radar (KICX), 232 km away, was scanning. The volume nearest the first event began at 20:49 UTC.
4 flash flood. Local standard time, as filed.
Flash flooding over Highway 160 was reported (Social Media and Law Enforcement) between on Highway 160 between Tonalea, Shonto, and Tsegi. Highway 98 was flooded near Shanto Wash.
The Dilkon Chapter House received multiple reports of Tribal members calling for help because of washed out dirt roads. Indian routes 6 and 7 were flooded between Indian Wells and White Cone.
The Cornfields Chapter House reported that water was overtopping Navajo Route 15 with Law Enforcement diverting traffic. Greaswood Springs Road to Klagetoh was flooded. State Route 264 was flooded near County Road 317.
The Havasu Creek Gauge at Supai Village showed water rising 4 feet in 30 minutes from 430 PM to 500 PM. The stream crested around 530 PM (1970 CFS) at 5 feet above normal levels . The flow remained elevated through 700 PM.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2022Every state in 2022This day in weather historyWarnings in Arizona, August 2022
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: 1052295, 1052802, 1052808, 1053138.