Thunderstorms with heavy rain produced flash flooding across portions of 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.
Thunderstorms with heavy rain produced flash flooding across portions of 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 Jul 20, 9:54 AM MST, 2 hours 36 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 954 AM MST Tue Jul 20 2021 .SYNOPSIS...Scattered showers and thunderstorms are forecast to develop each afternoon this week. Localized flash flooding will be possible with the stronger storms. Temperatures are expected to remain around normal to slightly below normal. && .UPDATE...Currently quiet conditions across the region with only a few weak showers in southwestern Yavapai County and over the Kaibab Plateau. Mostly clear skies across the region will allow for strong heating this morning. Expect convective buildup to initiate in the next hour with showers and thunderstorms starting before noon moving to the north-northwest. Look for another active day with scattered to numerous thunderstorms. Not to minimize the threat of severe thunderstorms with large hail and strong winds, our biggest concern for today and through the rest of the week is the threat for flash flooding in northern Arizona. Stay alert to changing weather conditions remember that flash flooding can occur miles away from the thunderstorm. Don't enter a flooded areas. Turn around, don't drown! && .PREV DISCUSSION /321 AM MST/...High pressure will remain over the Four Corners region through Thursday, maintaining monsoonal flow over Arizona. Typical scattered to numerous showers and thunderstorms are forecast to develop each afternoon, with isolated flash flooding and isolated large hail being the primary hazards. The medium range models prog a retrograding upper level low moving into New Mexico by Friday, then into Arizona Saturday and Sunday. This feature will likely create an uptick in monsoonal thunderstorm activity this weekend. The aforementioned low should then weaken and lift north of the region by Monday. However, diurnal thunderstorm activity is still expected. && .AVIATION...For the 18Z package...Expect mainly VFR conditions for the 24 hour TAF forecast period. SCT-NUMRS SHRA/TSRA and ISOLD +TSRA through 03Z. MVFR conditions possible in stronger storms. Sfc winds outside of storms generally light. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered to numerous afternoon and evening showers and thunderstorms are expected Tuesday and Wednesday. Some storms may produce locally heavy rainfall amounts. Expect light winds and near normal high temperatures outside of any storms. Thursday through Saturday...Expect an even higher chance of showers and thunderstorms during this period as an easterly wave moves over central Arizona. Widespread wetting rains and locally heavy rainfall are probable, with activity persisting in the overnight periods. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...DB/TM AVIATION...DB FIRE WEATHER...Peterson For Northern Arizona weather information visit weather.gov/flagstaff
The Flagstaff radar (KFSX), 113 km away, was scanning. The volume nearest the first event began at 19:29 UTC.
2 flash flood, 1 lightning, 1 heavy rain. Local standard time, as filed.
An estimated two feet of water flowing through Banning Creek over the low water crossing on East School House Gulch Road in the community of Groom Creek.
Lightning stuck near the Bright Angel Trailhead. Four people were injured and two of them were hospitalized.
A rain gauge in the town of Snowflake measured 1.97 inches of rain within an hour.
The Snowflake-Taylor Police Department reported flash flooding in Snowflake with 6 inches of water over the roadways and houses threatened in the West 1st Street area.
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: 978721, 979013, 978722, 978740.