Nocturnal thunderstorms caused flash flooding early in the morning. Other storms developed later in the day with more flash flooding.
Every event with a place to put it. Tap one for its entry below.
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.
Nocturnal thunderstorms caused flash flooding early in the morning. Other storms developed later in the day with more 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 Jul 22, 6:31 PM MST, 5 hours 29 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 631 PM MST Thu Jul 22 2021 .SYNOPSIS...Scattered showers and isolated thunderstorms begin to expand in coverage from east to west overnight. The threat of flash flooding will increase into the weekend as thunderstorms occur across much of northern Arizona. && .UPDATE...Widespread shower and thunderstorm activity continues across a significant portion of northern Arizona this evening. Flooding has been identified in Show Low, Flagstaff and other locations across the region. Do not walk or drive through flood waters. It only takes 6 inches of fast moving water to knock a person over and carry them away, 12 inches to carry away a small vehicle and 18 to 24 inches to carry away most large SUVs, trucks and vans. Most importantly, it is impossible to see if the road has washed out and just how deep the water has cut into the ground. Turn around, don't drown! && .PREV DISCUSSION /129 PM MST/...There is a significant threat of flash flooding from today through Saturday, and possibly Sunday. Severe thunderstorms are also possible from Friday afternoon into the overnight hours. High pressure remains entrenched over the Four Corners today and is bringing clockwise flow aloft across northern Arizona. Thunderstorms that formed over the high terrain are slowly beginning to move into the lower elevations on light steering flow. Localized heavy rainfall has been observed with these isolated to scattered thunderstorms. Expect expanding coverage of showers and storms throughout the remainder of the afternoon and evening hours today. A weak disturbance is rotating around the high pressure this afternoon in the central Rocky Mountains and is progged to enter the Four Corners area later this evening. Accompanying this will be enhanced dynamics to support overnight convection, beginning first in Apache County this evening and spreading southwestward overnight. High resolution guidance is showing high chances for widespread rainfall tonight in mainly northeastern and east- central Arizona, with areas of embedded heavy rainfall. The current Flash Flood Watch remains in effect until late Saturday evening for a prolonged threat of flash flooding. There is moderate confidence in a slight downturn in activity by mid to late Friday morning, but another round of afternoon/evening thunderstorms on Friday are likely. A second dynamic system, this time an inverted trough moving westward from the southern southern Rockies, will then provide enough support for another round of overnight heavy rainfall Friday night. The inverted trough is also progged to create enough wind shear to support prolonged updraft development over northern Arizona on Friday. The result would be a combination of heavy rainfall leading to flash flooding, but also some severe thunderstorms. The severe thunderstorm threat should be monitored even into Friday night on the leading edge of another large storm complex moving into the state from the east. Significant flash flooding is again possible into Saturday as an already saturated ground is favored to produce enhanced runoff. The synoptic setup on Sunday is following a trend that began yesterday where the inverted trough stalls out over southern Arizona and continues to produce heavy rainfall on Sunday. The current Flash Flood Watch will have to be monitored against growing confidence in these conditions for later this weekend. Scattered thunderstorm coverage remains in the forecast early next week, but a bit less than what is expected over the next few days, as moisture remains over northern Arizona. && .AVIATION...For the 06Z package...Shra/tsra coverage increasing across eastern Arizona and spreading west through the night. Areas of MVFR/IFR possible. Gusty outflow winds near any storm activity with otherwise light winds. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...There is a significant flash flood potential this afternoon through Saturday night. Scattered to numerous afternoon and evening showers and thunderstorms are expected today through Saturday with storms continuing into the overnight hours. Widespread wetting rain is likely with embedded areas of heavy rain. Storm coverage will begin to decrease by early next week. && .FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch through Saturday evening FOR AZZ006>008- 011>018-037-038-040. && PUBLIC...Kobold/NL AVIATION...Kobold FIRE WEATHER...NL For Northern Arizona weather information visit weather.gov/flagstaff
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
715 PM MST THU JUL 22 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0430 PM FLOOD 4 ENE SHOW LOW 34.26N 109.97W
07/22/2021 NAVAJO AZ PUBLIC
HIGHWAY 60 EAST OF SHOW LOW FLOODED AT
LITTLE MORMON LAKE ROAD.
&&
DMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
718 PM MST THU JUL 22 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0430 PM FLOOD 6 ENE SHOW LOW 34.27N 109.94W
07/22/2021 NAVAJO AZ PUBLIC
HIGHWAY 60 EAST OF SHOW LOW FLOODED AT
SECOND KNOLL TARGET RANGE ENTRANCE (N.F.
ROAD 206).
&&
DMThe Flagstaff radar (KFSX), 56 km away, was scanning. The volume nearest the first event began at 07:00 UTC.
10 flash flood, 3 heavy rain. Local standard time, as filed.
Just over two inches of rain fell on the west side of Young. There was heavy run off in area washes. This water drained into Cherry Creek.
Two and a half inches of rain fell in Forest Lakes since midnight.
Flood waters in the Paria River reached the river gauge near the Colorado River at 0500 and rose 3.3 feet in 15 minutes. The flood waters likely traveled down this slot canyon from Utah through the early morning hours.
Highway US 60 was closed between Mile Post 384 and Vernon due to flash flooding.
A stream gauge on Cherry Creek reported a 3.61 foot rise.
Water in Black Canyon Creek had receded across Maren Avenue to 6 to 8 inches by the time the Sherriff officer saw it in the morning. High water marks indicated that it was much higher at the flood crest.
Several reports of over-flowing drainages, rocks, and debris on the roads making them impassable.
Street flooding was reported in and around Prescott Valley. One road in Prescott Valley was washed out due to the flooding.
About 0.85 inches of rain fell in around 30 minutes from 325 PM to 355 PM near Page Springs.
Street flooding was reported in Cottonwood with water flowing over the road.
Heavy rain over the Rafael Fire caused a 4 foot rise on the Verde River at Clarkdale (an increase of at least 1,300 CFS).
Heavy rain caused Dry Creek to rise 2.5 feet in a flash flood.
Law Enforcement reported that Highway 191 was close due to flooding in St Johns at Water Street. There was 12 to 18 inches of water covering the road.
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, July 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: 979000, 979010, 979007, 978997, 978998, 979005, 979009, 979011, 979231, 979014, 979242, 979245, 979247.