Scattered thunderstorms moved southwest across southeast Arizona during the afternoon and evening hours. One storm caused wind damage and flash flooding at Organ Pipe Cactus National Monument.
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 TWC wrote it up.
Scattered thunderstorms moved southwest across southeast Arizona during the afternoon and evening hours. One storm caused wind damage and flash flooding at Organ Pipe Cactus National Monument. Another storm produced heavy rain upstream of and flash flooding at a swimming spot east of Rio Rico. One teenager drown when he was swept away by flood waters.
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 Tucson, AZ wrote its last area forecast discussion before the first event at Jul 29, 9:38 AM MST, 4 hours 25 minutes earlier.
Area Forecast Discussion National Weather Service Tucson AZ 938 AM MST Thu Jul 29 2021 .SYNOPSIS...Scattered to perhaps numerous storms are expected today into the weekend. High temperatures will run near to a few degrees below seasonal normals. && .DISCUSSION...No updates necessary this morning as the current forecast appeared to handle the trends well for today. Please refer to the previous discussion for more details on the current and projected weather. && .AVIATION...Valid through 30/18Z. Light shower activity this morning accompanied by CIGS between 10k- 15k feet. Widespread SHRA/TSRA is expected to develop this afternoon with multiple rounds of activity possible through late tonight. Storm impacts include strong erratic wind gusts in excess of 30 knots, heavy downpours, lowered vsbys, and CIGS dropping to 5k-9k feet. Storms will decrease in coverage overnight. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...More widespread storm activity is expected today with development beginning early this afternoon and lasting into tonight. Another active day is anticipated for Friday before a downward trend in storm activity begins going into early next week. Storms will likely produce erratic, gusty winds and locally heavy downpours. RH values remain well above critical thresholds through early next week. Temps will remain near to slightly below normal. 20- foot winds will generally be less than 15 mph when not influenced by thunderstorms. && .PREV DISCUSSION.../Issued 329 AM MST Thu Jul 29 2021/ Currently across southeastern Arizona a decaying MCV can be seen in radar imagery over the western portion of Cochise County moving west. This will continue to produce some light/moderate rain showers or sprinkles through the morning as it moves into Santa Cruz and southern Pima Counties. Another area of showers and a few embedded thunderstorms are moving across extreme northern Graham and Greenlee counties associated with a weak vort max, which is seen nicely in water vapor. It also appears to be shearing and weakening, but could certainly influence the weather for the northern half of the area later this afternoon as it moves west. Some of the high res models are hinting at this along with the HREF showing a focused area for convection across the northern portions of the CWA. If some organization can occur, strong gusty winds, heavy rain, and some blowing dust may be possible as storms move off the higher terrain and into portions of eastern Pinal County. A localized flash flood threat will also be possible given how saturated the ground is. Another area to watch will be outflows originating from northern Sonora convection. Some of the high res models hint at this moving southeast to northwest, likely generating thunderstorms along the bndrys. Some of this activity may persist into the overnight hours thanks to the easterly wave moving into the region. Heavy rain and gusty winds would be the main threats with this activity. A localized flash flood threat is also possible, especially with saturated grounds in place. Any training or cell mergers will enhance the threat. By Friday, the easterly wave will continue to move across northern Sonora. This will influence our weather with another round of showers and thunderstorms. There is lesser confidence on storm evolution depending on what happens later today. However, the western half of the CWA from Tucson to Ajo should be favored. The weakening easterly wave will begin to push north through Arizona later Friday into Saturday with lessening activity by as early as Sunday. There is decent agreement among the ensembles the high pressure briefly shifts to SW AZ and SoCal, before gradually moving back into the vicinity of the 4-Corners by late week. This return to the 4-Corners would signal another possible uptick if activity. Still plenty of time to watch how this evolves. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
The Yuma radar (KYUX), 180 km away, was scanning. The volume nearest the first event began at 21:01 UTC.
2 flash flood, 1 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds downed three power poles north of the Organ Pipe Cactus National Monument Visitor Center.
Heavy rain of 2 to 3 in less than 1 hour at Organ Pipe Cactus National Monument caused flash flooding of roadways making them impassible.
One inch of rain in less than 90 minutes caused rapid rises in Josephine Canyon. Two teenagers swimming near a waterfall were swept downstream by a rapid rise in the water level. One teenager drowned and another escaped the floodwaters while sustaining minor injuries and was later rescued.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Flash Flood, Santa Cruz | 2021-07-29 | 13 | Male | In Water | Direct |
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: 976539, 976541, 976546.