The active monsoon pattern continued over northern Arizona. A Flash Flood Watch was in effect from 11 AM MST to 11 PM MST in accordance with the Weather Prediction Center Excessive Rainfall Outlook (slight risk for northern Arizona).
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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.
The active monsoon pattern continued over northern Arizona. A Flash Flood Watch was in effect from 11 AM MST to 11 PM MST in accordance with the Weather Prediction Center Excessive Rainfall Outlook (slight risk for northern Arizona).
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 12, 9:25 AM MST, 55 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 925 AM MST Fri Aug 12 2022 .SYNOPSIS...Daily showers and thunderstorms will continue across much of northern Arizona through the weekend. Scattered to widespread thunderstorms are likely each afternoon, with flash flooding being the main threat. && .UPDATE...Storms are already firing up over the San Francisco Peaks this morning, leading to heightened flash flooding fears over the area. Expect storms to significantly increase in coverage today, first over the high country, before spilling over into the low country. Avoid vulnerable areas, like normally-dry washes, slot canyons, drainages, streams, etc. Heavy rainfall may turn spots like these into raging torrents. && .PREV DISCUSSION /217 AM MST/...The active monsoon pattern is expected to continue for the days to come. As a result, another Flash Flood Watch is in place for 11 AM MST to 11 PM MST Friday. This watch includes most of our CWA with the exception of the northeastern portion of our state. This was largely decided based on model guidance and the Weather Prediction Center Excessive Rainfall Outlook for Day 1, where there was a slight risk for northern Arizona. There could be a need for additional Flash Flood Watches in our CWA past today, but there are none in place at this time. Over the weekend...Thunderstorm activity will continue to dominate during the afternoon hours, primarily thanks to daytime heating. The late evening/overnight hours will likely remain the less active portion of each day for the near future. Expect another few days of above average PW values and high surface dewpoints as moisture continues to funnel in from the south. At this time, there are no major indications by models of our monsoon activity declining for this forecast period. Beginning of next week...The high pressure system currently centered over the Oklahoma Panhandle is looking to shift westward toward the Pacific Northwest. This transition will be caused by a deepening trough on the east coast. Even with the change in our synoptic pattern, there will still be a southerly flow aloft, continuing to move moisture into Arizona. && AVIATION...For the 18Z TAF package..Expect widespread showers and thunderstorms into the early evening hours becoming isolated by midnight. VFR conditions and light surface winds away from storms. Aviation discussion not updated for TAF amendments. && FIRE WEATHER...The active monsoon pattern continues today and Saturday with widespread shower and thunderstorm coverage. The main threats include flash flooding and gusty, erratic outflow winds. Light winds expected outside of storms with little change in temperatures. Sunday through Tuesday...Daily shower and thunderstorm activity will continue. Look for light winds with little change in temperatures. && && .FGZ WATCHES/WARNINGS/ADVISORIES... Flood Watch through this evening for AZZ004>008-012>018-037-038- 104>108-112>118-137-138. && PUBLIC...BJ AVIATION...McCollum FIRE WEATHER...McCollum For Northern Arizona weather information visit weather.gov/flagstaff
The Flagstaff radar (KFSX), 94 km away, was scanning. The volume nearest the first event began at 17:21 UTC.
5 flash flood, 1 hail. Local standard time, as filed.
Heavy rain over the Pipeline, Tunnel, and Schultz fire scars caused flash flooding in the area that closed Highway 89 in both directions.
A thunderstorm produced one inch diameter hail, heavy rain, and gusty winds (around 28 MPH).
The river gauge on Agua Fria measured a 5 foot rise in 15 minutes (starting at 1215 PM MST).
Heavy rain caused flash flooding in Rock Canyon Creek where the water rose 3.5 feet.
A video on social media showed flooding outside of a hose near Hotevilla. Another video showed water up to the road on Route 2 just south of Kykotsmovi Village. Hopi Police reported that water covered Highway 264 for a distance of 100 yards near mile marker 369 at 725 PM MST. Arizona Department of Transportation had to send crews out to removed mud from the flood.
Flooding was reported on Sate Route 98 near K'ai'bii'to.
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: 1053420, 1053421, 1053422, 1053423, 1053627, 1053664.