Here we go again.
A low-pressure system from the Gulf of Alaska is forecast to impact the San Francisco Bay Area from Monday through Wednesday, bringing more rain and wind to a region that was battered by a storm less than a week ago. This system is expected to reach peak intensity over the Pacific Ocean off the coast of the California-Oregon border before drifting south along the California coast and passing by the Bay Area.
The storm is expected to bring less severe impacts to the region than the last area of low pressure that passed directly over San Francisco, said Rick Canepa, a forecaster with the National Weather Service.
The National Weather Service expanded the Monday-Tuesday wind advisory to include the North Bay, East Bay and eastern Santa Clara hills in addition to the coastal areas. The advisory is in effect Monday night through Tuesday afternoon, with peak gusts expected to be up to 40 to 50 mph. Winds are expected to begin developing in the North Bay at about 11 p.m. Monday before spreading across the Bay Area. The strongest winds are forecast late tonight into Tuesday afternoon.
“It’s going be half as windy as it was in the last storm in general,” local meteorologist Jan Null with Golden Gate Weather Services told SFGATE. “There will be some spots that will see winds that are just as strong, but generally it will be less windy. The real problem is the soils are still saturated. We will still see some trees coming down .”
Weather models were in agreement Monday morning that the first rains will arrive in the North Bay at about 8 p.m. this evening. Rain is expected to spread gradually into the greater Bay Area, likely reaching San Francisco at about midnight, before pushing into Monterey County on Tuesday morning. The rainy weather will likely persist into Tuesday and Wednesday.
As this cold front pushes across Bay Area, rain rates are likely to range from 0.1 to 0.3 inch per hour, but they could jump up to 0.5 inch per hour intermittently, the weather service said.
“We could see rises on creaks, streams and rivers, but not significant rises to warning levels,” Canepa said. “We could see some brief flooding in urban areas.”
The weather service is predicting that between Monday and Wednesday, most of the Bay Area, including San Francisco, will see 1 to 1.5 inches of rain, while the North Bay could pick up 1 to 4 inches in the coastal mountains, and the Santa Cruz Mountains could see 2 to 3 inches.
Cold air moved into the Bay Area behind the last system, and the corridor of northwest winds has been open ever since, Canepa said. “It has been pretty much almost continuous cold,” he said.
With these chilly conditions in place, the Bay Area’s mountain peaks are forecast to be frosted in snow. Snow levels could initially be as low as 2,500 feet Monday night, but are expected to rise to 4,000 to 6,000 feet by early Tuesday morning as the cold front will bring in “a little bit of warmth,” Canepa said.
The East Bay hills could pick up 1 to 1.5 inches of snow, and the Mayacamas Mountains (near the Napa and Sonoma county borders with Lake County) could see 3 to 6 inches.
There’s a slight chance for thunderstorms Tuesday, and a slightly higher chance Wednesday when the low-pressure system skirts the Bay Area, Canepa said. “It looks like the system will be just over our coastal waters on Wednesday,” he said.