A shortwave trough rotating through the region led to steepening lapse rates and increasingly unstable conditions across central Arizona on the 16th. With abundant moisture and high CAPE values in place, the environment was favorable for the development of strong to severe thunderstorms. Thunderstorms initially developed over the high terrain of eastern Arizona before racing toward the west/southwest into the lower deserts of south-central Arizona as a line of strong to severe thunderstorms. The main impacts associated with these thunderstorms occurred as they moved into the Phoenix metro, producing widespread damaging wind gusts. Multiple observations recorded wind gusts in excess of 60 mph with a few approaching 80 mph. Recently implemented damage threat categories for Severe Thunderstorm Warnings were put to the test with one destructive Severe Thunderstorm Warning being issued for 80 mph wind gusts for much of Phoenix. There were numerous reports of downed trees across the Valley as a result of the severe wind gusts. The strong winds also led to several reports of dense blowing dust in dust prone areas. Additionally, thunderstorms produced locally heavy rainfall that led to several instances of flash flooding. No injuries were reported.

Thunderstorm Wind in PINAL, ARIZONA
From 16-AUG-21 22:45:00 to 16-AUG-21 23:00:00 (MST-7)
Location: MAGMA
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A large tree approximately 4 feet in diameter was uprooted near Oasis Lane and Hunt Highway. Additional large trees were reported down in a nearby subdivision. Reduced visibility was also reported due to blowing dust. Timing was estimated using radar. No injuries were reported.

Thunderstorm Wind in PINAL, ARIZONA
From 16-AUG-21 22:45:00 to 16-AUG-21 23:00:00 (MST-7)
Location: MAGMA
Magnitude: 50.00 EG
Property damage: 0.75K
Crop damage: 0.00K
Reported by: Trained Spotter

Multiple trees were reported down along Hunt Highway between Gary Road and Bella Vista Road. A fence was destroyed by a downed tree near Hunt Highway and Gantzel Road. No injuries were reported. Multiple trees were also reported to be uprooted along Charbray Drive between between Empire Boulevard and Skyline Drive. Timing was estimated using radar.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 22:53:00 to 16-AUG-21 22:53:00 (MST-7)
Location: (PHX)SKY HARBOR ARPT
Magnitude: 60.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The Phoenix Sky Harbor ASOS recorded a 69 mph gust.

Thunderstorm Wind in PINAL, ARIZONA
From 16-AUG-21 22:20:00 to 16-AUG-21 22:20:00 (MST-7)
Location: FLORENCE JCT
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A mature lemon tree along with multiple smaller trees with trunks approximately 8-10 inches in diameter were uprooted or broken. A saguaro was also pulled out of the ground. Timing was estimated using radar. No injuries were reported.

Thunderstorm Wind in PINAL, ARIZONA
From 16-AUG-21 22:40:00 to 16-AUG-21 22:40:00 (MST-7)
Location: MAGMA
Magnitude: 63.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The SRP Quail mesonet station recorded a 73 mph gust.

Thunderstorm Wind in PINAL, ARIZONA
From 16-AUG-21 23:14:00 to 16-AUG-21 23:14:00 (MST-7)
Location: RANDOLPH
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The SRP Randolph mesonet station near Coolidge recorded a 64 mph gust.

Thunderstorm Wind in PINAL, ARIZONA
From 16-AUG-21 22:56:00 to 16-AUG-21 22:56:00 (MST-7)
Location: MAGMA
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained weather spotter recorded a 59 mph gust on a home weather station.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:00:00 to 16-AUG-21 23:00:00 (MST-7)
Location: CHANDLER ARPT
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Photos on social media showed multiple trees uprooted along Cooper Road between Queen Creek Road and Ocotillo Road. No injuries were reported.

Flash Flood in GILA, ARIZONA
From 16-AUG-21 22:30:00 to 17-AUG-21 01:00:00 (MST-7)
Location: BORCH
Flood cause: Heavy Rain / Burn Area
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Heavy rainfall over the Salt Fire burn area led to enhanced runoff that resulted in flash flooding. The Arizona Department of Transportation reported closures along SR 188 north of Globe/Claypool due to flooding. Timing was estimated using a nearby USGS stream gage along Pinal Creek at Inspiration Dam, which rose over 3 feet beginning at 2145MST and crested at 4.47 feet near midnight. No damage or injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:05:00 to 16-AUG-21 23:05:00 (MST-7)
Location: CHANDLER
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Videos on social media showed multiple trees down along Pecos Road between McQueen Road and Cooper Road in Chandler. Videos also showed a large tree in this area blocking a roadway requiring a large pickup truck to remove it. No injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:04:00 to 16-AUG-21 23:04:00 (MST-7)
Location: FOWLER
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Public

Photos on social media showed a large tree down on power lines near Lower Buckeye Road between 67th Avenue and 75th Avenue. Timing of 60-65 mph winds was estimated using radar. No injuries were reported.

Lightning in PINAL, ARIZONA
From 16-AUG-21 22:40:00 to 16-AUG-21 22:40:00 (MST-7)
Location: MAGMA
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Photos on social media show a charred pickup truck after catching on fire from being struck by lightning in a neighborhood near Ocotillo Road and Schnepf Road. No injuries were reported. Timing was estimated using radar.

Dust Storm in NORTHWEST PINAL COUNTY, ARIZONA
From 16-AUG-21 23:18:00 to 16-AUG-21 23:28:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

An Arizona Department of Transportation webcam near Highway 347 and Cement Plant Road showed dense blowing dust estimated to be reducing visibilities below 1/4 mile. No accidents or injuries were reported.

Dust Storm in TONOPAH DESERT, ARIZONA
From 16-AUG-21 23:34:00 to 16-AUG-21 23:44:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

An Arizona Department of Transportation webcam on the Loop 303 near Bethany Home Road showed near zero visibility due to dense blowing dust. No accidents or injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:59:00 to 16-AUG-21 23:59:00 (MST-7)
Location: MOBILE
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The Maricopa County Flood Control District Mobile AZ ALERT mesonet station recorded a 60 mph gust.

Flash Flood in MARICOPA, ARIZONA
From 16-AUG-21 23:40:00 to 17-AUG-21 03:00:00 (MST-7)
Location: CHANDLER HGTS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Sossaman Road and Via Del Jardin was closed at Sonoqui Wash due to flooding. A nearby Maricopa County Flood Control District stream gage near Hawes Road recorded flow in the wash climbing above alarm stage at around 2340MST. Flow in the wash continued to increase during the early morning hours on the 17th before cresting above bank full at 7.10 feet and 2237 CFS at 0010MST. Timing was estimated using the stream gage. No damage or injuries were reported.

Hail in MARICOPA, ARIZONA
From 16-AUG-21 22:41:00 to 16-AUG-21 22:41:00 (MST-7)
Location: FOUNTAIN HILLS
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 22:45:00 to 16-AUG-21 22:45:00 (MST-7)
Location: SCOTTSDALE MUNI
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

A large uprooted tree was reported to have caused damage to a brick wall and a sprinkler system at a home near Cactus Road and 101st Street. No injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 17-AUG-21 07:30:00 to 17-AUG-21 08:30:00 (MST-7)
Location: CACTUS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Video on social media showed water rapidly flowing across 12th Street near the Torre Blanca community making the street impassable. No damage or injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:14:00 to 16-AUG-21 23:14:00 (MST-7)
Location: CACTUS
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Public

A social media photo showed a large uprooted tree down on a carport at an apartment complex. No injuries or damaged cars were reported. Timing was estimated using radar.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:14:00 to 16-AUG-21 23:14:00 (MST-7)
Location: SUNNYSLOPE
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Photos on social media showed a large tree approximately 40-50 feet tall snapped in half near 35th Avenue and Peoria Avenue. No injuries were reported.

Flash Flood in PINAL, ARIZONA
From 17-AUG-21 00:11:00 to 17-AUG-21 01:11:00 (MST-7)
Location: COOLIDGE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

The Arizona Department of Transportation reported that SR 87 was closed due to flooding near Arizona Boulevard. No damage or injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:08:00 to 16-AUG-21 23:08:00 (MST-7)
Location: SUN LAKES
Magnitude: 50.00 EG
Property damage: 1.50K
Crop damage: 0.00K
Reported by: Public

Photos on social media showed a large uprooted tree along Alma School Road between Ray Road and Chandler Boulevard, causing damage to a block wall along with knocking down a light pole. No injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:15:00 to 16-AUG-21 23:15:00 (MST-7)
Location: GUADALUPE
Magnitude: 66.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A weather station located at the Gila River Valley Lookout on South Mountain measured a 75.6 mph gust.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 22:50:00 to 16-AUG-21 23:00:00 (MST-7)
Location: SCOTTSDALE
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Helicopter footage from a local TV station showed a large uprooted tree down on a home near Scottsdale Road and Chaparral Road. Footage also showed another large tree down at a nearby apartment complex, resulting in damage to the pool area and to one of the apartment buildings. Approximately 1 mile to the northeast, a large tree 2 feet in diameter was reported to have snapped in half along 82nd Street across from Saguaro High School. No injuries were reported. Timing was estimated using radar.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:16:00 to 16-AUG-21 23:16:00 (MST-7)
Location: TWIN KNOLLS
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A downed power pole was reported near Ellsworth Road and Brown Road in Mesa. No injuries were reported.

Thunderstorm Wind in PINAL, ARIZONA
From 16-AUG-21 23:16:00 to 16-AUG-21 23:16:00 (MST-7)
Location: CASA GRANDE ARPT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

The Casa Grande Municipal Airport AWOS (KCGZ) recorded a 58 mph gust.

Flash Flood in MARICOPA, ARIZONA
From 17-AUG-21 05:15:00 to 17-AUG-21 06:15:00 (MST-7)
Location: PHOENIX TURF ARPT
Flood cause: Heavy Rain
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Heavy rain flooded the underpass of I-17 at Greenway Road with at least one driver becoming stuck. No injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 17-AUG-21 06:30:00 to 17-AUG-21 07:30:00 (MST-7)
Location: GLENDALE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Maricopa County Flood Control District stream gage ACDC at 43rd Avenue exceeded alarm stage resulting in downstream impacts at Thunderbird Paseo Park. Timing was estimated from when the gage reach alarm stage and time to travel downstream. No damage or injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:04:00 to 16-AUG-21 23:04:00 (MST-7)
Location: PAPAGO AAF ARPT
Magnitude: 50.00 EG
Property damage: 17.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Photos on social media showed downed power poles near 44th Street and Indian School Road. Additional photos showed a couple of snapped palm trees down in the same area causing severe damage to a vehicle as well as to the the gate of a driveway. No injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:45:00 to 16-AUG-21 23:45:00 (MST-7)
Location: LITCHFIELD JCT
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: NWS Employee

Several downed trees were reported within neighborhoods surrounding Estrella Parkway and Yuma Road. The largest downed tree was approximately 40 feet tall. No injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 17-AUG-21 08:00:00 to 17-AUG-21 09:00:00 (MST-7)
Location: PERRYVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

The City of Goodyear reported that Citrus Road was closed between I-10 and Van Buren Street as well as Yuma Road and Durango Street due to flooding. No damage or injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 22:55:00 to 16-AUG-21 22:55:00 (MST-7)
Location: HELENA
Magnitude: 59.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A 68 mph gust was recorded by a trained weather spotter using a handheld anemometer near Baseline Road and Rural Road.

Thunderstorm Wind in MARICOPA, ARIZONA
From 16-AUG-21 23:10:00 to 16-AUG-21 23:10:00 (MST-7)
Location: SUNNYSLOPE
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A photo on social media showed a large uprooted tree down on some power lines near 15th Avenue and Glendale Avenue. No injuries were reported.