Flash Flood in La Paz County, Arizona

Flooding with water 3-4 feet deep was reported along US-95 about 14 miles south of Quartzsite. No damages or injuries were reported.

Under a classic setup for storm motion from the Northern Arizona high terrain to Southern Arizona lower deserts, with the monsoon 500mb high positioned over Nevada and Utah, a few multicell storm clusters developed and progressed west-southwest through the lower deserts in the afternoon and evening hours of the 2nd. Increased east-northeast steering flow resulted in relatively high shear values for the monsoon (Sfc-6km shear around 25-30 kts) and very steep mid-level lapse rate (8-8.5 C/km) supported the organized multicellular storm mode with robust updrafts. Inversely, very high DCAPE values, up to 1500-1800 J/kg, supported very strong downbursts. Moisture levels were also above normal which, in combination with the strong updrafts, supported high rainfall rates (1.5-2 inches per hour average). There were a few multicell clusters that moved through Southern Arizona. One through the southeast parts of the greater Phoenix area, another that developed in Yavapai County before descending southwest along US-60 in Maricopa and La Paz Counties, and a third that developed off the Kofa Wilderness terrain south of Quartzsite before being caught by the cluster descending along US-60. Each cluster produced damaging winds, dense blowing dust, small to severe hail, and localized flash flooding.