A slow moving cluster of intense thunderstorms developed across far southwestern Arizona during the afternoon hours on September 9th, and they affected the city of Yuma as well as surrounding communities such as Somerton and Fortuna Foothills. Due to the very humid and unstable nature of the atmosphere, the storms generated strong, gusty and damaging microburst winds well in excess of 60 mph. The gusty winds were sufficient to down power lines and tree limbs. Three separate Severe Thunderstorm Warnings were issued for the area around Yuma, due both to the slow movement and continued regeneration of the severe thunderstorms. No injuries were reported due to the severe weather.

Thunderstorm Wind in YUMA, ARIZONA
From 09-SEP-12 17:32:00 to 09-SEP-12 17:32:00 (MST-7)
Location: EL PUEBLECITO
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

A cluster of slow moving and very intense thunderstorms developed in the Yuma area during the afternoon hours on September 9th. The storms generated strong and gusty microburst winds. At 532 pm, the official ASOS weather station at the Yuma airport measured a gust to 65 mph, or 56 knots. Earlier, at 524 pm, the Yuma ASOS measured a gust of 58 mph. Finally, at 530 pm a trained weather spotter 2 miles northwest of Yuma estimated a peak wind gust to 65 mph. The trained spotter did not report damage associated with the strong wind gust.

Thunderstorm Wind in YUMA, ARIZONA
From 09-SEP-12 17:10:00 to 09-SEP-12 17:15:00 (MST-7)
Location: BLAISDELL
Magnitude: 55.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A cluster of slow moving and very intense thunderstorms developed across far southwest Arizona during the afternoon hours on September 9th, and they affected the city of Yuma as well as surrounding communities such as Fortuna Foothills. The storms developed strong, gusty and damaging microburst winds measured in excess of 60 mph. According to a trained weather spotter in the Fortuna Foothills, Interstate 8 was closed from Avenue 3E to Foothills Boulevard due to downed power lines. The closure took place at 515 pm. In addition, an amatuer radio operator 7 miles east of Yuma reported power lines down at 510 pm. The winds that blew down the power lines were estimated to be at least 60 mph. There were no reports of power poles blown down, however.

Thunderstorm Wind in YUMA, ARIZONA
From 09-SEP-12 17:30:00 to 09-SEP-12 17:30:00 (MST-7)
Location: SOMERTON
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A cluster of slow moving and very intense thunderstorms developed in the Yuma and Somerton area during the afternoon hours on September 9th. The storms generated strong, gusty and damaging microburst winds. According to a trained weather spotter 4 miles southeast of Somerton, wind gusts estimated to be at least 60 mph picked up and blew a metal shed a distance of approximately 30 yards. Another homeowner in Somerton had a 8 by 10 foot shed shifted several degrees off of its foundation by high winds. Also, the winds broke off a number of tree limbs estimated to be 4 inches or greater in diameter. Finally, as seen in a video posted on ABC15.com, strong thunderstorm wind gusts blew down about 40 feet of block wall in the back yard of an area homeowner. The falling wall nearly fell on top of man who was in the back yard, attempting to see if the 60 mph winds would support him if he fell face-first into the wind.

Heavy Rain in YUMA, ARIZONA
From 09-SEP-12 17:00:00 to 09-SEP-12 19:15:00 (MST-7)
Location: SOMERTON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A cluster of slow moving and intense thunderstorms developed in the Yuma and Somerton areas during the late afternoon hours on September 9th. In addition to damaging microburst winds, the storms produced locally heavy rainfall with peak rain rates well in excess of one inch per hour. At 613 pm, a trained weather spotter 4 miles southeast of Somerton reported very heavy rain. The spotter measured three quarters of an inch of rain in a forty minute period. The heavy rain prompted the issuance of a Small Stream Flood Advisory at 510 pm, and led to flooding of area roads and washes, such as the Fortuna Wash.