Marine surges are only suppose to last 2 possibly 2.5 days. This one is on its 4th day. Part of the answer is in the blog link below. But today marine surge winds at Sherman Island are being sustained in part by an eddy well west of the Golden Gate.

Take a look satellite video from this morning and note the counter-clockwise spinning winds that are sending southerly flow to Sherman Island.  Without this  eddy the marine surge would have fades away to just upper teens at Sherman Island this morning and the NW winds would have returned to the coast and the Peninsula. Notice the NW winds on the western edge of the eddy. These are the North Pacific High’s surface NW winds.Marine surgeEddyANIM