Jul 31, 2012
A large moisture surge moved over the area as monsoon flow rotated around the western edge of an upper high over the southern plains and into southern California. Daytime heating, along with a low to mid-level circulation coming up from the south, was sufficient to create the instability needed for thunderstorms over the mountains and deserts during the two-day period of the 30th and 31st. Heavy rain was the main threat from these storms and resulted in several instances of flash flooding, most
Source: NOAA National Weather Service Storm Events Database (event 398076). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Riverside County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.