Flash flood watch issued for Sunday
Highlighting a remarkable beginning to the winter rainy season, the National Weather Service on Friday issued a flash flood watch for parts of the Greater Bay Area as a powerful storm continued to churn toward Northern California, bringing with it heavy rains and gusty winds to the region on Saturday night and Sunday.
The category 5 atmospheric river storm — the highest on a scale of 1 to 5 — is forecast to deliver the most rain to the Bay Area Sunday of any day in more than two years.
“The Bay Area is ground zero,” said Marty Ralph, director of the Center for Western Weather and Water Extremes at UC San Diego. “We are still on track for a major storm.”
The storm, which will arrive Saturday night from the Pacific Ocean and continue until Monday morning, could bring up to 9 inches of rain in the North Bay, 5 inches in the Santa Cruz Mountains, and 1 to 3 inches in Bay Area cities, the National Weather Service said.
The last time San Francisco received more than 2 inches of rain in 24 hours was 32 months ago — on Feb. 13, 2019. The last time a storm this big hit the Bay Area in late October was 11 years ago, Ralph’s research found.
“We’re going to have slick roads, some flooded intersections, power outages,” said Jan Null, a meteorologist with Golden Gate Weather Services in Half Moon Bay. “This is a real winter storm. It has significant wind and significant rain.”
With 35 mph winds expected Sunday and gusts up to 60 mph in some areas, falling trees and power lines are a concern. PG&E warned widespread power outages were possible.
The utility has put 350 crews on standby from across the state, said PG&E spokeswoman Deanna Contreras,
with triple the normal number in some areas.
“It’s pretty much all hands on deck. Anyone who will be available for this weekend will be working,” she said.
Because of California’s ongoing two-year drought, emergency officials don’t expect rivers to flood. But there were growing concerns about mudslides where fires burned in the Santa Cruz Mountains, Sonoma and Napa counties, Big Sur and the Diablo Range east of Milpitas to Gilroy. The National Weather Service’s flash flood watch includes those areas.
“This is an exceptionally wet and strong system,” said Ryan Walbrun, a meteorologist with the National Weather Service. “Out of an abundance of caution, we wanted to draw attention to the burn scars.”
Officials in Santa Cruz County said they were considering potential evacuations for up to 200 homes in the most high-risk areas where the CZU Lightning Complex Fire in August 2020 destroyed 1,400 structures and burned nearly 90,000 acres between Boulder Creek and Big Basin Redwoods State Park.
“We are concerned with the weather,” said Nicole Coburn, assistant county administrative officer for Santa Cruz County. “We are trying to figure out if there might need for narrow evacuations.”
The Sierra Nevada region was expected to receive 2 to 3 feet of new snow. The National Weather Service issued a winter weather watch from Mount Shasta through Lake Tahoe and down to the Southern Sierra, warning of chain controls and closed roads in the mountains.
The powerful storm follows a week of rain across Northern California. But much more will be needed to bring up reservoir levels around the state after the driest two years in a row since 1976-77, water managers said.