SAN FRANCISCO (CBS SF) — A strong winter storm will bring heavy rain, high winds and possible flooding this weekend to the San Francisco Bay and Monterey Bay areas.
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Rain began Friday night with the heaviest rain forecast for Saturday night and Sunday, National Weather Service officials said.
The coastal mountains will get the heaviest rain. Flash flood watches are in effect for higher elevations and on some coasts.
National Weather Service meteorologist Brian Garcia said the storm is forecast to be a 10-year storm, which does not mean a storm like this happens every 10 years.
Rather, it means there is a 10 percent chance a storm like this occurs any year, Garcia said.
“Historically it’s nothing out of the ordinary,” he said.
Still, city, county and federal officials as well as officials with PG&E are asking people to be prepared. Emergency managers encourage residents to have enough supplies to survive without power for three days.
Flooding is possible along the Napa River at St. Helena. A flood warning has been issued for the Napa River, Calistoga officials said. A flood warning means flooding is imminent or occurring.
National Weather Service officials have forecast the Napa River will flood at least part of St. Helena but the city’s public works director Steve Palmer questioned that prediction.
Palmer said the current flood stage of 16 feet hasn’t been adjusted since a flood mitigation project was completed several years ago.
Palmer said city officials are more concerned about flooding along Sulphur Creek. The water rises rapidly during storms and could affect a couple of businesses that may need to evacuate, he said.
Elsewhere in the North Bay, upwards of 12 inches of rain is expected to fall on Mt. Tamalpais over the weekend. Homes are built along the mountainside and landslides and mudslides are possible, Garcia said.
Homes along the edges of the Soberanes and Loma wildfires are also at risk from damage because the rain could bring debris from the burned areas to the homes.
Garcia said rain will fall everywhere in the two bay areas.
High winds are expected starting early Saturday morning. The winds combined with saturated soils could cause trees to fall on power lines and knock out power.
The strongest winds will be in the mountains. A high wind advisory for higher elevations goes into effect at 4 a.m. Saturday.
Many cities are offering sand bags to residents. Check with city officials to find out where to get them.
Rain is expected to taper off on Monday before another system affects the bay areas on Tuesday, according to weather officials.
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