SAN FRANCISCO (CBS 5 / KCBS / BCN) — A pair of storms headed to the Bay Area could bring with them as much as ten inches of rain by Christmas Eve.

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The rainfall was expected to start on Friday, when the first of storms arrived.

“The storm center is coming down from the Gulf of Alaska and grabbing moisture and warm air from the western Pacific,” National Weather Service forecaster Steve Anderson said.

Warmer air is able to hold more moisture, prompting forecasters to predict that the wet weather on the way could last as long as a week.

“There is no day between now and next Thursday that will not see some rainfall,” said San Francisco State University meteorologist Jan Null.

The brunt of the first storm is expected to hit the Bay Area on Saturday and will likely last all day, the weather service said, bringing two to five inches of rain and accompanied by winds between 30 and 45 mph.

Anderson said current weather models suggested that authorities could issue wind, small craft, and urban and small stream flooding advisories over the weekend.

Forecasters expected the brunt of the second storm to come on Tuesday night into Wednesday morning.

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The coastal hills and moutains around Santa Cruz and Big Sur will easily see rainfall in the double digits from the two storms in this above-normal rainfall December, Null said.

KCBS’ Matt Bigler Reports:

Some local agencies were offering free sandbags for residents who want to shore up before the storm, especially in locations that have flooded in the past.

Anyone wanting to pick up sandbags should contact their local public works agency.

In addition, Santa Clara Valley Water District spokesman Marty Grimes advised Bay Area residents to clean out their gutters now.

He noted that even residents who don’t live on a flood plain could feel the effects of the impending storm systems.

“They still drive the highways and if the highways are flooded, their commute could be impacted,” Grimes said.

An especially strong storm, for example, could overflow the Guadalupe River, impacting traffic on the adjacent roadways such as Highway 87.

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