Thunderstorms continued to develop across the south central Arizona deserts during the evening hours on August 21st, affecting both the greater Phoenix area as well as portions of northwest Pinal county including the community of Coolidge. Due to the very moist and unstable nature of the atmosphere, the thunderstorms primarily generated very heavy rainfall with rain rates well in excess of 2 inches per hour. The heavy rain was sufficient to cause some urban street flooding. Additionally, a few storms were able to produce gusty and damaging microburst winds which were strong enough to blow down power poles.

Thunderstorm Wind in PINAL, ARIZONA
From 21-AUG-12 19:40:00 to 21-AUG-12 19:45:00 (MST-7)
Location: COOLIDGE ARPT
Magnitude: 65.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Scattered thunderstorms developed across northwest Pinal county, including the community of Coolidge, during the evening hours on August 21st. Some of the thunderstorms produced strong, gusty and damaging microburst winds which were estimated to be at least 65 knots. According to a trained weather spotter located on the west side of Coolidge, gusty microburst winds blew down a number of trees at approximately 740 pm. The diameter of the trees was not specified. In addition, there was shingle damage on several roofs. A Severe thunderstorm Warning was in effect at the time of the damage.

Heavy Rain in MARICOPA, ARIZONA
From 21-AUG-12 20:30:00 to 21-AUG-12 22:00:00 (MST-7)
Location: GOODYEAR ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms developed across the western portion of the greater Phoenix area during the evening hours on August 21st. The storms produced locally heavy rainfall with rain rates well in excess of one inch per hour. At 9 pm, radar estimates and storm spotter reports indicated that one half inch or more of rain had fallen since 830 pm. At 857 pm a trained spotter in Goodyear reported that one half inch of rain had fallen within the past 15 minutes. The heavy rain led to urban flooding and prompted the issuance of an Urban and Small Stream Advisory for the western Phoenix metropolitan area. The advisory continued until 11 pm.

Thunderstorm Wind in PINAL, ARIZONA
From 21-AUG-12 19:15:00 to 21-AUG-12 19:15:00 (MST-7)
Location: COOLIDGE
Magnitude: 60.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms developed across portions of northwest Pinal county, including the community of Coolidge, during the evening hours on August 21st. Due to the very humid and unstable nature of the atmosphere, the thunderstorms were able to produce both heavy rain and gusty, damaging microburst winds. According to local law enforcement, at 715 pm thunderstorm wind gusts knocked down several power poles and power lines in the town of Coolidge. The wind gusts were estimated to be at least 60 knots. At the same time, locally heavy rain produced by the severe storm cluster caused street flooding to the north, in the town of San Tan Valley. The urban flooding was reported by a trained storm spotter 15 miles north of Coolidge.

Heavy Rain in PINAL, ARIZONA
From 21-AUG-12 18:30:00 to 21-AUG-12 21:00:00 (MST-7)
Location: COOLIDGE ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Scattered thunderstorms developed across northwest Pinal county during the evening hours on August 21st, and they affected communities such as Coolidge, San Tan Valley and Arizola. Due to the very humid and unstable nature of the atmosphere, the storms were able to produce very heavy rainfall with rain rates well in excess of 2 inches per hour. At 720 pm, a trained weather spotter 1 mile west of Coolidge reported that he had  measured 2.54 inches of rain, and street flooding was occurring in the area. At 815 pm, another trained weather spotter near Coolidge measured 2.07 inches of rainfall, much of which had fallen since 7 pm. The heavy rain led to the issuance of a Flash Flood Warning for the Coolidge area beginning at 7 pm and continuing through 830 pm. Heavy rain continued to fall into the mid evening; at 9 pm another trained weather spotter 2 miles north of Arizola measured nearly one inch of rain in a thunderstorm and nearly one half inch had fallen in the last 25 minutes.