An MCS developed in the afternoon in Yavapai and Mohave counties and spread southwest through La Paz and Yuma counties through the evening and early overnight hours. In an otherwise week steering wind, the MCS was partially maintained by strong low level wind shear as it progressed downslope through a moisture-rich environment. The MCS produced widespread 40 plus mph wind gusts, locally higher, with multiple damaging wind reports. Given the high moisture content, storms with the MCS and the slow-moving storms that developed well out ahead of the MCS produced very heavy rainfall, leading to areas of flash flooding. Radar estimated rainfall was upwards of 2 to 3 inches in 1 hour for many areas, with locally higher amounts.

Flash Flood in LA PAZ, ARIZONA
From 10-AUG-21 20:30:00 to 10-AUG-21 21:30:00 (MST-7)
Location: QUARTZSITE ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Video on social media, posted at 2057MST, showed an estimated 6 inches of swift-moving water through the intersection of Mockingbird Street and Plymouth Road in Quartzsite. Timing based on radar. No damages or injuries reported.

Thunderstorm Wind in LA PAZ, ARIZONA
From 10-AUG-21 18:40:00 to 10-AUG-21 18:40:00 (MST-7)
Location: PARKER
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A 1 foot diameter mesquite tree fell on a home near 15th Street and Ocotillo Avenue. Damage to the home was not reported. Timing estimated from radar and wind estimated from damage report. No injuries reported.

Thunderstorm Wind in LA PAZ, ARIZONA
From 10-AUG-21 18:30:00 to 10-AUG-21 18:30:00 (MST-7)
Location: LAKESIDE
Magnitude: 56.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Law Enforcement

La Paz County Sherriff's Office reported the roof (possibly a car port and roof combination based on street view) of a mobile home was torn off in strong winds and some shingles were in nearby powerlines. Timing estimated from radar and winds estimated from damage report. No injuries were reported.

Flash Flood in LA PAZ, ARIZONA
From 10-AUG-21 20:05:00 to 10-AUG-21 21:30:00 (MST-7)
Location: QUARTZSITE ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

State Route 95 was closed at mile post 111 due to flooding. Time estimated by radar. No damages or injuries reported.

Thunderstorm Wind in LA PAZ, ARIZONA
From 10-AUG-21 18:55:00 to 10-AUG-21 18:55:00 (MST-7)
Location: VICKSBURG
Magnitude: 55.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A CWOP station, E4845 Salome, near Vicksburg Junction measured a 63 mph wind gust. This is a known suspect weather station in terms of wind speed reliability, but the timing lines up with a strong outflow boundary on radar. A severe thunderstorm warning was in effect at the time which supports the gust magnitude. The station also measured up to 72 mph, but given the questionable station reliability this was not used.

Thunderstorm Wind in LA PAZ, ARIZONA
From 10-AUG-21 18:40:00 to 10-AUG-21 18:40:00 (MST-7)
Location: PARKER
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Multiple trees were down around Parker including a palm tree that fell into the street along the 900 block of California Avenue/State Route 95. Timing estimated from radar and wind estimated from damage report. No injuries were reported.