Strong thunderstorms across south-central Arizona produced damaging winds, hail and extremely heavy rainfall. Heavy rain with near zero visibility led to a massive traffic pileup in downtown Phoenix.

Heavy Rain in MARICOPA, ARIZONA
From 28-AUG-10 18:00:00 to 28-AUG-10 18:45:00 (MST-7)
Location: PHOENIX
Property damage: 200.00K
Crop damage: 0.00K
Reported by: Newspaper

Strong thunderstorms with extremely heavy rain led to mutiple collisions on Interstate 10 in downtown Phoenix during the afternoon hours on August 28. A total of 69 vehicles were involved in a series of crashes; one collision alone involved 35 vehicles and spanned over 2 miles from 16th street to 7th street. Trained spotters reported visibilities below one quarter mile in heavy rain in downtown Phoenix, and it was low visibility in heavy rain that led to the collisions. Seven people were taken to area hospitals and two were in serious condition. Fire officials medically evaluated at least 40 people.

Thunderstorm Wind in PINAL, ARIZONA
From 28-AUG-10 18:30:00 to 28-AUG-10 19:00:00 (MST-7)
Location: LIRIM
Magnitude: 50.00 EG
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotters reported that throughout Maricopa, over 13 power poles were blown down by thunderstorm microburst wind estimated to be in excess of 60 kt. In addition, numerous buildings sustained roof damage and trees up to 10 inches in diameter were blown over.

Thunderstorm Wind in MARICOPA, ARIZONA
From 28-AUG-10 17:55:00 to 28-AUG-10 18:00:00 (MST-7)
Location: SUNNYSLOPE
Magnitude: 50.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported that power poles were blown down at 19th Avenue and Dunlap. The poles were downed by thunderstorm microburst winds estimated to be in excess of 50 kt.

Thunderstorm Wind in MARICOPA, ARIZONA
From 28-AUG-10 17:40:00 to 28-AUG-10 17:50:00 (MST-7)
Location: WEST CHANDLER
Magnitude: 50.00 EG
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter near South Mountain Park reported that multiple large tree limbs, at least 7 inches in diameter, were blown down by strong thunderstorm winds estimated to be in excess of 50 kt.

Heavy Rain in MARICOPA, ARIZONA
From 28-AUG-10 18:00:00 to 28-AUG-10 18:45:00 (MST-7)
Location: CACTUS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter in Phoenix measured 1.24 inches of rainfall between 1800MST and 1845MST. The rain fell in the area near 16th Street and Northern.

Heavy Rain in PINAL, ARIZONA
From 28-AUG-10 18:30:00 to 28-AUG-10 20:30:00 (MST-7)
Location: CASA BLANCA
Crop damage: 0.00K
Reported by: Trained Spotter

Strong thunderstorms produced locally heavy rainfall across portions of west central Pinal county, including the town of Maricopa and the Ak-Chin Village. Radar and trained spotters indicated up to 3 inches of rain fell along the Santa Rosa and Green washes, and several reports of curb-to-curb street flooding in Maricopa were received.

Thunderstorm Wind in MARICOPA, ARIZONA
From 28-AUG-10 17:55:00 to 28-AUG-10 17:55:00 (MST-7)
Location: SUNNYSLOPE
Magnitude: 60.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Power poles were blown down at 19th Ave and Dunlap.

Thunderstorm Wind in PINAL, ARIZONA
From 28-AUG-10 15:30:00 to 28-AUG-10 15:45:00 (MST-7)
Location: LIRIM
Magnitude: 50.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported that power poles were blown down at the junction of the Casa Grande Highway, and north White and Parker Road. Winds were estimated to be in excess of 50 kt.

Thunderstorm Wind in PINAL, ARIZONA
From 28-AUG-10 18:26:00 to 28-AUG-10 18:40:00 (MST-7)
Location: LIRIM
Magnitude: 50.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Amateur Radio

An amateur radio operator reported six inch diameter trees blown down in south central Maricopa. A trained spotter also reported a couple tree limbs blown down near the town of Maricopa. Winds were estimated in excess of 50 kt.

Thunderstorm Wind in MARICOPA, ARIZONA
From 28-AUG-10 18:10:00 to 28-AUG-10 18:55:00 (MST-7)
Location: SCOTTSDALE MUNI
Magnitude: 60.00 EG
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported numerous large tree branches down on Shea Boulevard, partially blocking traffic. The trees limbs were downed by strong thunderstorm winds estimated to be in excess of 50 kt. In addition, there was minor flooding along Shea between 120th and 136th street. In Fountain Hills very strong winds blew trees down and blew tiles off roofs, according to the Fountain Hills Times. Nearly every major street in Fountain Hills had tree limbs down, according to Ken Kurth.