May 7, 2017
An upper level strong trough of low pressure moved down the California coast on May 6th, becoming an unseasonably deep (552 DM at 500 mb) closed low over Southern California on the 7th. An associated surface low tracked from San Bernardino County south along the San Diego County coast. The two combined to produce favorable up-slope flow near Palomar Mt. and Birch Hill that resulted in nearly a foot of snow, setting records for May. Elsewhere snowfall was limited to 2 to 5 inches above 5000 ft. S
Source: NOAA National Weather Service Storm Events Database (event 700440). 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.