FloodZoneMap.org

The combination of the subtropical high pressure over Colorado and an upper trough over west coast led to south-southwest flow over much of the region. Thunderstorm activity during the afternoon hours developed across southwest Maricopa County as well as across the Mogollon Rim area. By the mid to late evening hours, colliding outflows from these storm complexes led to the development of additional thunderstorm activity across the Phoenix area, especially across the central and northern portions