Aug 12, 2017
A weak monsoon pattern that had persisted for several days produced 2 separate isolated supercell thunderstorms over the San Diego County desert late in the afternoon on the 12th. The storm was fueled by a surge in low level moisture late in the day. Storm tops exceeded 60,000 ft and storm top divergence was near 100 kt.
Source: NOAA National Weather Service Storm Events Database (event 720675). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in San Diego County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.