One of the biggest winter storms to hit the Bay Area in the last 10 years is expected to quickly dump inches of rain and blast residents with powerful winds Thursday and Friday, the National Weather Service said.
“Bottom line … now is the time to prepare before the storm on Thursday,” forecasters for the National Weather Service’s Bay Area region said in a statement. "Preparations should be made ASAP.”
Mountains lining the coast from Sonoma to Santa Cruz could get as much as 8 inches of rain by Thursday morning, said meteorologist Charles Bell. Some wind gusts could be as powerful as 70 mph.
Forecasters say the storm is bigger than the one that dumped inches of rain on Southern California a week ago and triggered a few rock and mud slides along Pacific Coast Highway and the San Gabriel Mountains.
Though the worst of the storm is expected to affect Northern California, it will still bring wet and windy weather to Los Angeles and Ventura counties. Moderate to heavy rain could last up to six hours, increasing the risk of debris flows in communities recently scorched by wildfires. Wind gusts could reach up to 70 mph in foothill communities. Along the coast, the storm will bring rising surf, strong rip currents and beach erosion. By Friday morning, most of the heavy rain is expected to diminish.
In Northern California, people living above 6,000 feet in areas like Lassen National Park and Donner Pass could have a blizzard, forecasters say. A winter storm warning will be in effect from 10 p.m. Wednesday until 1 p.m. Friday. The weather service said residents could experience whiteout conditions, which could lead to roadway closures lasting several hours. Ten to 20 inches of snow could accumulate in those communities.
The northern Sierra crest could get 2 to 3 feet of snow, with the heaviest snowfall Thursday night. The strongest winds there are expected Wednesday night and Thursday with 20 to 25 mph winds and gusts more than twice that. Snow is expected to fall as low as 4,500 feet on Thursday night and Friday morning.
This winter storm features an "atmospheric river," which can be up to 400 miles wide and can cause major flooding when stalled over an area, according to the weather service.
The rivers are relatively narrow regions in the atmosphere responsible for transporting water vapor horizontally outside the tropics, the weather service says. On the West Coast, the weather event is also known as the Pineapple Express.