By CBS San Francisco Staff

SAN FRANCISCO (CBS SF) — Just a week after large waves and a treacherous rip tide claimed the lives of a father and his two young children, forecasters warned beachgoers to be an alert for massive waves, some towering as high a 30 feet, crashing onto beaches Sunday from Sonoma County to Monterey.

Michael Wyman, 40, drowned last Sunday afternoon at Blind Beach near Jenner while attempting to save his 4-year-old son and 7-year-old daughter, who were swept out to sea by the turbulent waves. The children remain missing and are presumed to have died.

Large waves and violent surf also claimed the life of a man who was swept off the rocks near Beach Boulevard and Paloma Ave. in Pacifica in December.

Storm systems well out into the Pacific were whipping up monster waves once again this weekend. The National Weather Service has issued a high surf warning Sunday for the Bay Area Pacific Ocean beaches.

“A new large, long period northwest swell arrives on Sunday which will result in breaking waves from 23 to 28 feet, and locally up to 30 feet at favored breakpoints,” weather service forecasters warn. “A High Surf Warning will be in effect through much of Sunday for an increased risk of rip currents and large shore break.”

A wave forecast for the legendary Mavericks surf break off the San Mateo coast showed swells building later Sunday afternoon, topping off at about 31 feet by 6 p.m.

The dangerous surf also was joined by cold water temperatures.

“Sea surface temperatures remain cold, down in the lower to mid 50s,” forecasters said. “Cold water drownings occu each year with these events but are avoidable by remaining a safe distance from the coastline. Continued vigilance is advised.”

There is also the threat of coastal flooding from King Tides.

“King Tides have returned to the region and will ebb and flood on Monday,” forecasters said. “Large, long period swell and highest high
tides of the year will overlap and allow the intrusion of seawate into low lying areas, generating minor coastal flooding. The highest of the high tides is expected on Monday morning.”

The storms are churning up a large northwest swell. Among the areas most exposed to the northwest swells are San Francisco’s Ocean Beach; San Mateo County’s Montara State Beach; Monterey County’s Marina State Beach and Monastery Beach in Carmel.

“These large waves can be erratic and unpredictable and may injure or knock beachgoers into the cold, turbulent ocean,” forecasters warned.