Thunderstorms developed during the evening hours across portions of the south central Arizona deserts on August 28th, and they affected the greater Phoenix metropolitan area. The atmosphere was both very moist and unstable and this allowed thunderstorms to generate strong and damaging outflow winds in addition to heavy rain and flash flooding. The winds, estimated to be in excess of 60 mph, were strong enough to blow down dozens of large trees in the Waddell area around 8 pm. A variety of products were issued during the evening hours including Small Stream Flood Advisories, Flash Flood Warnings and Severe Thunderstorm Warnings.

Flash Flood in MARICOPA, ARIZONA
From 28-AUG-13 19:00:00 to 28-AUG-13 23:50:00 (MST-7)
Location: LITCHFIELD JCT
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Department of Highways

Scattered thunderstorms developed across the western portions of the greater Phoenix area during the evening hours on August 28th. Due to the very moist nature of the atmosphere, the storms produced locally heavy rains with rainfall rates reaching 2 inches per hour. At about 1930MST a trained spotter 4 miles west of Luke Air Force Base measured 2 inches of rain within one hour. Locally heavy rain continued in communities such as Litchfield Park, Goodyear and Buckeye. Due to the heavy rains, a Flash Flood Warning was issued at 2020MST for the west valley communities and it was in effect until 2215MST. It was later re-issued at 2248MST due to continued rainfall and remained in effect through 0145MST on August 29th. According to the department of highways, flash flooding occurred at 10 pm 4 miles west of Litchfield Park; the Loop 303 was closed between Interstate 10 and Glendale due to high flowing water. The closure lasted until approximately midnight.

Thunderstorm Wind in MARICOPA, ARIZONA
From 28-AUG-13 20:35:00 to 28-AUG-13 20:35:00 (MST-7)
Location: BUCKEYE MUNI ARPT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Thunderstorms with strong ang gusty winds developed across the western portions of the greater Phoenix area during the evening hours on August 28th. The AWOS wind sensor at the Buckeye airport measured a wind gust to 50 knots.

Thunderstorm Wind in MARICOPA, ARIZONA
From 28-AUG-13 19:45:00 to 28-AUG-13 20:40:00 (MST-7)
Location: WADDELL
Magnitude: 65.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Trained Spotter

On August 28th, thunderstorms developed during the evening hours across the western portions of the greater Phoenix area, affecting communities such as Waddell, El Mirage and Luke Air Force Base. Due to the very unstable nature of the atmosphere, the stronger storms produced damaging wind gusts estimated to be at least 75 mph. At 1945MST, a trained weather spotter about 2 miles northwest of Waddell reported that dozens of trees were blown down with diameters as high as 3 feet. Shortly thereafter, a trained spotter 2 miles southwest of Luke AFB reported power poles blown down near Loop 303 and Bethany Home Road. Another trained spotter 2 miles northwest of Waddell reported that 7 to 8 eucalyptus trees were blown down. These trees were approximately 60 feet tall with diameters of 2 feet. Finally, at 2037MST a report was received via amatuer radio regarding large and mature Mesquite trees that were blown down 2 miles northwest of El Mirage. A Severe Thunderstorm Warning was issued for the Luke and Waddell area, starting at 1923MST and continuing in effect through 2015MST.