An upper level low sitting over central Arizona on the 11th and 12th led to the development of multiple rounds of showers and thunderstorms across the region. Anomalously high moisture in the region allowed this activity to produce heavy rainfall which led to multiple instances of flash flooding across south-central and southwest Arizona. Some of these thunderstorms became strong to severe and produced strong wind gusts that led to several reports of damage. No injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 11-AUG-21 18:50:00 to 11-AUG-21 18:50:00 (MST-7)
Location: LITCHFIELD PARK
Magnitude: 56.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Public

Several large trees were reported down across a neighborhood near Litchfield Park due to damaging wind gusts from severe thunderstorms in the area. Additionally, minor roof damage to two homes was reported with approximately 5-10 roof tiles damaged on each home. Winds were estimated to be around 55-65 mph. No injuries were reported.

Flash Flood in GILA, ARIZONA
From 11-AUG-21 03:55:00 to 11-AUG-21 04:55:00 (MST-7)
Location: MIAMI
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Department of Highways

The Arizona Department of Transportation reported that US 60 was closed between Superior and Miami (mileposts 226-243) due to water over the roadway and erosion causing damage to a guardrail and right lane of the highway along Bloody Tanks Wash near milepost 242. No injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 11-AUG-21 11:00:00 to 11-AUG-21 12:00:00 (MST-7)
Location: FT MCDOWELL
Flood cause: Heavy Rain / Burn Area
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The USGS stream gage along Sycamore Creek near Fort McDowell recorded two rapid rises during the morning on the 11th. A 2.73 foot rise occurred in 15 minutes from 0900MST to 0915MST and a 3.60 foot rise occurred in 30 minutes from 1030MST to 1100MST. At 1100MST, the creek crested at 6.29 feet. No injuries or damage were reported.

Flash Flood in MARICOPA, ARIZONA
From 11-AUG-21 16:55:00 to 11-AUG-21 17:55:00 (MST-7)
Location: MATTHIE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A photo on social media showed flash flooding occurring in Flying E Wash in Wickenburg with significant flow over Vulture Mine Road north of US 60, resulting in the closure of the road. No damage or injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 12-AUG-21 06:45:00 to 12-AUG-21 07:15:00 (MST-7)
Location: CAVE CREEK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A Maricopa County Flood Control District stream gage recorded Cave Creek north of Carefree Highway climbing above alarm stage, impacting downstream low water crossings such as Canyon Creek Road. At 0632MST, the creek crested at 6.06 feet. No damage or injuries were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 11-AUG-21 18:45:00 to 11-AUG-21 18:45:00 (MST-7)
Location: DREAMLAND VILLA
Magnitude: 52.00 EG
Property damage: 175.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Several planes reported to be either flipped over or damaged along with sheet roofing damage at one of the hangars at Falcon Field Municipal Airport. Wind gusts in the area were estimated to be around 55-60 mph with a 55 mph gust recorded at the airport. No injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 12-AUG-21 06:00:00 to 12-AUG-21 07:00:00 (MST-7)
Location: CAREFREE
Flood cause: Heavy Rain / Burn Area
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Videos on social media showed a low water crossing along Bartlett Dam Road at Camp Creek being impassable as a result of approximately 6-8 inches of flowing water over the road. Additionally, Horseshoe Dam Road between Bartlett Dam Road and Horseshoe Lake was closed by Tonto National Forest due to flood damage. No injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 12-AUG-21 06:15:00 to 12-AUG-21 08:15:00 (MST-7)
Location: FT MCDOWELL
Flood cause: Heavy Rain / Burn Area
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heavy rainfall over the Bush burn scar led to enhanced runoff into Sycamore Creek. A USGS stream gage along Sycamore Creek near Fort McDowell recorded a rapid 10 foot rise in the creek approximately between 0500MST and 0600MST. At 0600MST, the creek crested at 11.15 feet. No injuries or damage were reported.

Flash Flood in MARICOPA, ARIZONA
From 12-AUG-21 08:11:00 to 12-AUG-21 09:11:00 (MST-7)
Location: FT MCDOWELL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

The Maricopa County Department of Transportation reported that Needlerock Road was closed at Rio Verde Drive due to flooding. No damage or injuries were reported.

Thunderstorm Wind in LA PAZ, ARIZONA
From 12-AUG-21 19:40:00 to 12-AUG-21 19:40:00 (MST-7)
Location: QUARTZSITE ARPT
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Multiple trees were reported down on Highway 95 in the northern part of Quartzsite. Bypassers assisted a deputy to remove a large tree that was blocking the highway. Debris from properties was also reported to have blown onto residential streets in Quartzsite. No injuries were reported.

Flash Flood in LA PAZ, ARIZONA
From 12-AUG-21 19:54:00 to 12-AUG-21 20:54:00 (MST-7)
Location: BOUSE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

The La Paz County Sheriff's Office reported that traffic was at a standstill along Highway 72 north of Bouse due to a wash running across the roadway. No damage or injuries were reported.

Thunderstorm Wind in LA PAZ, ARIZONA
From 12-AUG-21 19:46:00 to 12-AUG-21 19:46:00 (MST-7)
Location: BRENDA
Magnitude: 50.00 EG
Property damage: 45.00K
Crop damage: 0.00K
Reported by: Department of Highways

The Arizona Department of Transportation along with chasers in the area reported that multiple semi trucks had been blown over on I-10 westbound east of Quartzsite near mile post 41, resulting in the closure of the interstate. No injuries were reported.

Thunderstorm Wind in YUMA, ARIZONA
From 12-AUG-21 19:00:00 to 12-AUG-21 19:00:00 (MST-7)
Location: TACNA
Magnitude: 50.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: COOP Observer

Numerous power poles were blown down along Avenue 40 E between E County 6th Street and E County 8th Street. No injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 12-AUG-21 14:51:00 to 12-AUG-21 15:51:00 (MST-7)
Location: BOSQUE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Highway patrol reported to the Arizona Department of Transportation that flooding was occurring on SR 238, leading to the closure of the highway. No injuries or damage were reported.

Thunderstorm Wind in MARICOPA, ARIZONA
From 11-AUG-21 18:14:00 to 11-AUG-21 18:14:00 (MST-7)
Location: SIL MURK
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The Gila Bend landfill mesonet station MAGL measured a 61 mph gust.

Flash Flood in MARICOPA, ARIZONA
From 11-AUG-21 21:55:00 to 11-AUG-21 22:55:00 (MST-7)
Location: LIBERTY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Increased flow in Waterman Wash led to flash flooding at a low water crossing on Narramore Road, resulting in a closure of the road. A nearby Maricopa County Flood Control District stream gage along Waterman Wash at Rainbow Valley Road recorded a peak flow of 2.51 feet. Timing was estimated using the nearby stream gage.

Flood in MARICOPA, ARIZONA
From 12-AUG-21 19:00:00 to 13-AUG-21 02:45:00 (MST-7)
Location: APACHE WELLS
Flood cause: Planned Dam Release
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Releases at Granite Reef Dam were conducted in response to increased flow in the Salt/Verde River systems from the recent heavy rainfall. The Maricopa County Flood Control District stream gage along the Salt River below Granite Reef Dam showed flow peaking early in the afternoon on the 12th at 3,763 CFS. This resulted in increased flow down the Salt River, which impacted downstream unbridged crossings. Further downstream, a Maricopa County Flood Control District stream gage along the Salt River at Val Vista Drive showed flow from the upstream release peaking at 2,109 CFS. According to the Maricopa County Department of Transportation, McKellips Road was closed from SR 202 to Alma School Road due to the flooding caused by the releases. Timing was estimated using the stream gages and approximate downstream travel time to the areas impacted. No damage or injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 11-AUG-21 17:30:00 to 11-AUG-21 18:30:00 (MST-7)
Location: BOSQUE
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 238 was closed due to flooding. The location was estimated based on the area with the heaviest rainfall and information provided on social media by ADOT. No damage or injuries were reported.

Flash Flood in MARICOPA, ARIZONA
From 12-AUG-21 09:50:00 to 12-AUG-21 10:50:00 (MST-7)
Location: NEW RIVER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A Maricopa County Flood Control District stream gage along Skunk Creek climbed above alarm stage, impacting downstream roads such as Dixileta Drive. The gage peaked at 3.60 feet. Timing was estimated based on travel time information provided by the Maricopa County Flood Control District. No damage or injuries were reported.