Dec 13, 2021
A low pressure system descended from the Gulf of Alaska southward along the entire Pacific Coast and tapped into sub-tropical moisture originating from the Central Pacific to drop heavy rain throughout the state. A stalled frontal boundary over the Santa Cruz Mountains along with strong southerly winds from a coastal low-level jet, enhanced orographic rainfall over this region, leading to rainfall totals over a 2 day period (Dec 12th-13th) of up to ten inches in the coastal mountains. The stalle
Source: NOAA National Weather Service Storm Events Database (event 1000075). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Alameda County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.