Q&A: A look at the big waves pounding California beaches
By ALICIA CHANG, Associated Press
May 4, 2015 4:32 PM CDT
Big waves challenge surfers at Malibu, Calif., as a long-period, south swell moved into the Southern California Bight on Sunday, May 3, 2015. The National Weather Service said the swell, with a period of about 20 seconds, would translate to surf of 5 feet to 8 feet with local sets to 10 feet at favored...   (Associated Press)

LOS ANGELES (AP) — Big waves have been lashing Southern California, attracting surfers and thousands of gawkers to south-facing beaches.

Beach patrols were stepped up Monday after lifeguards rescued 17 people off Newport Beach over the weekend.

A high-surf advisory remained in effect through Tuesday.

Here's a look at the latest surf conditions:

WHY ARE THE WAVES SO HUGE?

A recent storm off New Zealand triggered powerful swells that raced toward Southern California thousands of miles away. High surf began pounding the coast early Sunday.

HOW BIG ARE THE WAVES?

The highest surf was predicted Monday, with some sets topping more than 12 feet along beaches in Orange and San Diego counties and 10 feet at Malibu and Zuma in Los Angeles County, according to the National Weather Service.

Lifeguards at the Wedge in Newport Beach, a popular bodysurfing spot, reported 15-foot waves Monday afternoon.

HOW OFTEN DOES SOUTHERN CALFORNIA GET STORM-TRIGGERED WAVES?

It's not uncommon for Southern California to experience heavy surf generated by faraway storms or hurricanes.

South-facing beaches get pounded by storm-triggered swells about a dozen times a year, typically in the summer and fall, said Stuart Seto, a weather specialist with the National Weather Service in Oxnard.

"They're very destructive to coastal beaches because they carry away a lot of sand," Seto said.

WHAT HAS BEEN THE IMPACT?

Large waves Sunday night caused minor flooding in low-lying Seal Beach where water surged over the boardwalk. No homes were damaged.

Earlier in the day, a cruise ship was forced to dock in San Diego because of high surf and long swells in Long Beach. Passengers scheduled to sail on the next cruise were taken by bus from Long Beach to San Diego.

WHAT ARE THE POTENTIAL DANGERS?

While the waves are a dream for surfers, meteorologists and lifeguards warned of strong rip currents and dangerous swimming conditions.

They also cautioned beach-goers about so-called sneaker waves— large and powerful waves that can appear without warning.

Inexperienced swimmers were urged to stay out of the water because strong riptides could pull them under.

People were also warned not to climb on jetties and rocks for fear of being swept away. Boaters were asked to secure their vessels moored at south-facing harbors.

"We want everybody to be safe," said Newport Beach Chief Lifeguard Rob Williams.