Aa high pressure circulation centered near the Four Corners allowed deep monsoon moisture to become thoroughly entrenched across northern Arizona. Surface dew points were generally above 60 F south of the Mogollon Rim, with values in the 50s along and north of the Rim.
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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.
Aa high pressure circulation centered near the Four Corners allowed deep monsoon moisture to become thoroughly entrenched across northern Arizona. Surface dew points were generally above 60 F south of the Mogollon Rim, with values in the 50s along and north of the Rim. Precipitable water ranged from 1.0 to 1.75 inches, with the highest values across southern Yavapai County.
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 9, 9:42 AM MST, 3 hours 17 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 942 AM MST Tue Aug 9 2022 .SYNOPSIS...Deep monsoonal moisture will remain across much of northern Arizona through the week. Scattered to widespread thunderstorms are likely each afternoon during this time. Flash flooding will again be the main threat, especially near recent fire scars. && .UPDATE...Scattered showers and thunderstorms are expected to develop across the region this afternoon and evening, with the greatest coverage expected mainly over the high terrain. Cloud cover and earlier preciptation from a decaying MCS moving into Mojave County has stabilized much of western portions of the region, thus, likely contributing to a delayed start in storms this afternoon. 12Z HREF guidance shows areas of mix-layer CAPE values of around 500-1500 J/Kg this afternoon mainly along and south of I-40. This combined with fairly weak (~15 kts) 0-6km shear will limit the overall severe threat today. Flooding will however remain a concern as PWAT values remain high, around 1.0 to 1.5 inches, although faster storm motion around 10-15 kts does limit the overall threat outside of training storms. Updated PoPs through the overnight to delay the start of convection and reduce chances this afternoon. && .PREV DISCUSSION /316 AM MST/...For today, a high pressure circulation centered near the Four Corners will allow deep monsoon moisture to become thoroughly entrenched across northern Arizona. Surface dew points are generally expected to be above 60 F south of the Mogollon Rim, with values in the 50s along and north of the Rim. In addition, precipitable water is expected to range from 1.0 to 1.75 inches, with the highest values across southern Yavapai County. In terms of instability, above 1000 J/kg is predicted to develop along and south of the Mogollon Rim this afternoon, coincident with the area of greatest moisture. North of the Rim, less instability is anticipated, with CAPE likely ranging from 500-1000 J/kg. 0-6km Bulk shear will be low, with values in the 5-15 knot range. In this moderate CAPE, but low shear environment, the severe weather threat remains low, although a few strong storms capable of producing hail up to 1 inch in size cannot be ruled out. Most high resolution model guidance shows the typical daily trend, with storms forming over high terrain around noon, before outflow boundaries initiate new storms within valleys during the mid-afternoon and evening hours. The strongest of these storms is expected to occur along and south of the Mogollon Rim as that is where the greatest instability is forecast. Individual storm motion will be toward the northwest between 10-15 mph. Due to the uptick in monsoon moisture, and the relatively slow moving nature of today's storms, the flash flood threat will increase. As a result, a Flash Flood Watch has been issued for this afternoon and evening for areas from the Mogollon Rim south, including the White Mountains and Grand Canyon country. From Wednesday into next week, an active monsoon pattern is forecast to continue as high pressure strengthens over the central United States and a moist southerly wind persists across Arizona. Good chances for showers and thunderstorms are forecast each day for the foreseeable future. && .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 Wednesday. Heavier cells will produce brief MVFR/IFR. Sfc winds light. Aviation discussion not updated for TAF amendments. && FIRE WEATHER...Scattered to widespread showers and thunderstorms will bring good chances for wetting rainfall today and Wednesday. The main hazards from these storms are flash flooding and strong thunderstorm winds. Otherwise, expect light winds far from storm activity with little change in temperatures. Thursday through Saturday...Monsoon moisture will remain in place bringing daily showers and thunderstorms. Winds will remain light outside of storm activity with little change in temperatures. && .FGZ WATCHES/WARNINGS/ADVISORIES... Flood Watch through this evening for AZZ004-006>008-015>018-037- 038-104-106>108-115>118-137-138. && PUBLIC...Humphreys/RR AVIATION...Peterson FIRE WEATHER...RR For Northern Arizona weather information visit weather.gov/flagstaff
The Flagstaff radar (KFSX), 143 km away, was scanning. The volume nearest the first event began at 20:00 UTC.
1 thunderstorm wind, 1 flash flood. Local standard time, as filed.
A thunderstorm wind gust of 76 MPH was reported just northeast of Peeples Valley.
The river gauge at Granite Creek showed nearly a 4 foot rise in one hour. It rose from 7.19 feet at 230 PM to 10.96 feet at 320 PM. Ten feet is considered moderate flood stage and 11 feet major flood stage. The gauge dropped below major flood stage at 445 PM and below flood stage at 545 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: 1052183, 1052185.