The National Weather Service issued high surf advisories Thursday morning for large portions Northern California, with waves up to 30 feet high expected to hit portions of the coast until Sunday.

An increasingly ferocious and volatile surf is raising questions about the future of the state’s piers, which have defined the coastline for generations.

Large waves of 25 to 35 feet were expected along the Northern California coast on Tuesday and a high surf warning is in effect until 6 p.m.