SAN FRANCISCO – The wave of storms battering California are far from over, and it’s too early to calculate the cost of damage to homes and businesses overwhelmed by floodwaters.

But the final tally will be in the billions of dollars, says Trevor Burgess, CEO of Neptune Flood, among the nation’s largest private flood insurance companies. Only 2% of homeowners in California have flood insurance, he said, adding that standard homeowners insurance does not cover flood damage.

A recent climate assessment by the U.S. Global Change Research Program found that “atmospheric rivers” such as those sweeping across California will become more common and more severe as global temperatures increase.

“Unfortunately, these sorts of flooding events are the new normal and can no longer be considered a one-in-100-year sort of event,” Burgess said.

WHAT IS AN ATMOSPHERIC RIVER?These rivers of water vapor can extend thousands of miles

Other developments:

►Dozens of major roads around the state remain closed because of flooding and slide concerns, the state Department of Transportation says. Caltrans districts across the state are “strongly advising the public to avoid traveling if you can.”

►The Palisades Tahoe ski resort, formerly known as Squaw Valley, reported it had received 300 inches of snowfall so far this season. The Mammoth Mountain resort in the Eastern Sierra said it has gotten 444 inches of snow at the summit.

►At least 18 people have died in the unrelenting wave of storms that have rolled across the state since late December, state officials say. Most of the deaths have been caused by falling trees and cars swept away on flooded roads.

►The 12.37 inches of rain San Francisco received from Dec. 26 through Monday represent more than half its typical yearly total and the city’s third-highest amount ever over 15 days, meteorologist Jan Null said.

ATMOSPHERIC RIVER TAKES AIM AT SAN FRANCISCOBay Area; more flooding possible: California storm updates

Drivers urged, ‘Turn around, don’t drown,’ when encountering flooded road

With another atmospheric river expected to hit Northern California this weekend, the National Weather Service has issued a flood watch for the San Francisco Bay Area that extends from early Saturday morning until 4 p.m. Monday.