An isolated supercell thunderstorm moved west across southern Pima County during the late afternoon. It produced damaging winds and flash flooding north of Sasabe, then split over the Baboquivari Mountains where the southern cell continued to produce damaging winds in the southeast part of the Tohono O'odham Nation.
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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 TWC wrote it up.
An isolated supercell thunderstorm moved west across southern Pima County during the late afternoon. It produced damaging winds and flash flooding north of Sasabe, then split over the Baboquivari Mountains where the southern cell continued to produce damaging winds in the southeast part of the Tohono O'odham Nation. Meanwhile scattered thunderstorms moved west across northern Graham into Pinal County, and produced damaging winds in the San Carlos Apache Tribe reservation community of Peridot.
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 9, 2:23 PM MST, 1 hour 15 minutes earlier.
Area Forecast Discussion National Weather Service Tucson AZ 223 PM MST Fri Jul 9 2021 .SYNOPSIS...We'll keep enough moisture around for isolated to scattered thunderstorms the next few days, with temperatures running several degrees above average for much of the area. Then conditions look favorable for an increase in thunderstorm activity by early next week. && .DISCUSSION...Slow start to thunderstorm initiation today. A few storms have developed over the Rim, with cumulus clouds gradually increasing over the mountains of Pinal/Pima/Santa Cruz Counties. Dew points are still in the low 60s to upper 50s in those areas, but drier area is approaching from the east. This should keep Cochise County fairly quiet for today. Storm motion is toward the west/southwest at a decent pace of around 20 kts. SPC Meso Analysis shows a good amount of instability over the more moisture rich areas, with a line of low-level convergence along the advancing easterly dry airmass. HREF favors the region southwest of Tucson for thunderstorms later this afternoon into the evening along with whatever tries to move off the Rim. Overall, it's generally a low- grade monsoon day. Tomorrow is shaping up to be a more organized Rimshot event resulting in widespread thunderstorm chances as precip propagates all the way out into the lower deserts overnight. This scenario is aided by a better moisture profile and some cooling aloft which helps erode the persistent inversion we've been dealing with the past few days. Steering winds are a touch more northeasterly as well as the high repositions a little more to the west over Las Vegas. Over the next several days the high meanders about this general area, keeping persistent northeasterly flow for us. Daily thunderstorm chances will continue, and model guidance is really hitting the Tuesday-Thursday period. GEFS M-Climate percentiles for QPF shows a broad portion of our CWA in the 90th percentile and above. The high weakens at this time and an easterly wave tracking across Mexico pushes deep moisture into our region. Still hard to pinpoint which days might be most active, but high temps drop several degrees and the flash flooding threat is likely to increase during this time. && .AVIATION...Valid through 11/00Z. SKC to SCT clouds 9k-14k ft MSL through most of the period except SCT-BKN with layers above through 10/06z. Isolated-SCT SHRA/TSRA from the White Mountains southwest to Santa Cruz county potentially affecting the KTUS and KOLS terminals this evening. Wind gusts to 40 kts possible near any TSRA. Otherwise, surface winds less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated to scattered thunderstorms today into the evening hours. Saturday has the potential for a stronger rim shot event with storms propagating to the SW. A further increase is expected next week with a more favorable environment for storms, similar to last week. Min RH values will generally be in the 15-25 percent range for lower elevations through Monday with very good overnight recoveries before increasing Tuesday onward. Surface winds will be light and follow normal daily trends when not influenced by storms. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && Discussion...Howlett Aviation/Fire Wx...Cerniglia Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Special Weather Statement National Weather Service Tucson AZ 252 PM MST Fri Jul 9 2021 AZZ503-092215- Upper Santa Cruz River and Altar Valleys including Nogales- 252 PM MST Fri Jul 9 2021 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL PIMA COUNTY UNTIL 315 PM MST... At 251 PM MST, Doppler radar was tracking a strong thunderstorm near Arivaca, or 12 miles west of Tubac, moving west at 5 mph. Dime size hail and winds in excess of 40 mph will be possible with this storm. Locations impacted include... Arivaca and Arivaca Lake. PRECAUTIONARY/PREPAREDNESS ACTIONS... Heavy rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 3170 11117 3153 11118 3154 11146 3173 11147 TIME...MOT...LOC 2151Z 094DEG 6KT 3163 11127
The Tucson radar (KEMX), 80 km away, was scanning. The volume nearest the first event began at 22:38 UTC.
3 thunderstorm wind, 1 flash flood. Local standard time, as filed.
The Sasabe RAWS measured a wind gust of 66 mph.
Thunderstorm winds destroyed a dwelling at Cold Fields.
More than 1 inch of rain in less than 1 hour fell along State Route 286 north of Santa Margarita Road west to the Baboquivari Mountains causing a number of washes to flow east across Route 286 two to three feet deep.
Thunderstorm winds downed a tree, which well on a vehicle at Rodeo Lane near Highway 70 in Peridot.
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: 975659, 975662, 975669, 975667.