Rain has closed roads and prompted urban flood warnings today, and weather forecasters say it's likely to get worse this weekend before it gets better.

While today's rain has snarled traffic throughout the Bay Area, the North Bay appears to be seeing the worst effects.

The National Weather Service issued an urban flood warning this afternoon for Marin, Sonoma and Napa counties, signaling that rain could pool in low lying areas and on roads and cause ponds and streams to overflow.

State Highway 1 is closed just south of Tomales Petaluma Road in Marin County in both directions due to flooding, the California Department of Transportation said this afternoon.

The roadway was closed shortly before 2 p.m. and will reopen when the water recedes, a department statement said.

The National Weather Service has also issued a hazardous weather advisory for the entire Bay Area and a high surf advisory for areas including San Francisco, the Peninsula and the coastal North Bay. Large waves could occasionally break far up onto beaches, potentially sweeping beachgoers and fishermen into the water.

The rain is expected to continue this weekend, with highs in the mid 40s to mid 50s around the Bay Area, according to a National Weather Service meteorologist. Sunday morning, a stronger storm is expected that carries a chance of thunderstorms.

"We'll have pretty robust rainfall amounts, but not so heavy that we have big flooding issues," said meteorologist Austin Cross. "Urban area will see a third to half an inch, the hills could see up to one to two inches."

The storm is expected to end Sunday night, but another system could arrive by the evening of Christmas Day.

"There will be some breaks in there," Cross said. "It looks like probably Monday will be a nice enough day, but overall it will be pretty wet and cold."

Pacific Gas and Electric officials say Sunday's storm, in particular, could cause problems including power outages.

"We're expecting windy conditions especially in the higher elevations, in the North Bay, Peninsula and portions of the East Bay as well," said PG&E spokesman Joe Molica. "We urge folks to be prepared out there."

Molica noted that anyone experiencing a power outage should use flashlights and battery-operated radios, not candles. A phone with a cord is also good to have, he noted.

"A cordless phone won't work in a power outage, and a cell phone might work only for a limited period of time," Molica said.

Residents are encouraged to freeze water in 2-liter bottles ahead of the storm so that they can keep items in the refrigerator cool if the power goes out, Molica said.

In addition, anyone who spots a downed power line should assume it is live and call 911 and PG&E immediately.

— Bay City News Service

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