Just a few enemy submarines present off American Atlantic west coast according to the U.S. Joint Intelligence Committee. Daily summary dated 27 December 1941

An item reported that according to J.I.C. comments numerous reports of enemy submarines off the West Coast were availlable although it were actually just two possible three submarines most likely off Cape Mendico (200 miles north of San Francisco) and San Luis Obespo (200 miles south of San Francisco).

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 17 dated 27 December 1941.