well I just heard a nasty rumor that you are in the southern CA area
So do tell: when you say "storm", is this stuff coming from the erosion caused by storm water runoff? ie.: like the channel exits where creeks and ditches exit to the sea, thus carving a gully? Or is there some ocean-spawned erosion (ie.: cuts, slopes, scallops, etc...) eroding by the surf itself?
I've found that the annual ditch channels carved by storm-water runoff tend to carve the same path, year after year, straight from the outlet, to the ocean. Thus even though it may look impressive, it's not the same as cuts caused by the erosion of the waves/swells, which can cut into older sand, that isn't the same each year.
I haven't seen any particular southern swells. But perhaps the local winds have been sufficient to whip up local windchop enough? Up here (central coast CA) we haven't seen enough southern swells or winds to do much, but I heard that Southern CA was getting pounded with more inches of rain than us, and thus perhaps more wind, etc... ?