A Pacific storm lashed northern and central California on Thursday with heavy rain and high winds, knocking out electricity to tens of thousands of homes, disrupting commercial flights and prompting school closures in the San Francisco Bay area.
Nearly 240 departing and incoming flights had been canceled at San Francisco International Airport by late morning, with delays for other flights averaging two hours, airport duty manager Bob Ritiski said.
A downtown San Francisco subway station serving the financial district was closed through the morning commuter rush due to a power outage, and the city's electrified bus system was halted in many areas, transit officials said.
Winds howled through Sacramento, the state capital, with gale-force gusts rattling buildings and whipping through trees before dawn, followed by heavy downpours just as the morning commute was getting started.
The National Weather Service issued flash-flood, high-surf and high-wind advisories ahead of the storm, warning that torrential rains could lead to mudslides in foothill areas stripped of vegetation by wildfires earlier in the year.
The Shasta Lake area of northern California received 5 inches (13 cm) of rain overnight, and up to 4 inches (10 cm) was expected in California's Central Valley, the state's agricultural heartland, as well as in Sacramento, according to the Weather Service.
"The fact that it looks like so much of it is going to fall in such a short period of time, that's one of the major concerns," Weather Service meteorologist Charles Bell said.
The Pacific Gas and Electric Company reported that nearly 227,000 customers lost power during the storm Thursday morning, with cities in the peninsula area south of San Francisco hardest hit by outages.
Several Bay area school districts, including San Francisco, Oakland and Berkeley, canceled classes due to the storm.
The storm was expected to spread by Thursday night into Southern California, which was hit by its first storm of the season last week, bringing record amounts of rainfall to some areas. A third storm system has been forecast for this weekend.
The flurry of rain will provide some measure of relief from a record, multi-year drought that has forced water managers to sharply reduce irrigation supplies to farmers and prompted drastic conservation measures statewide, weather officials said.
As much as 3 feet (1 meter) of snow is predicted this week for the higher elevations of the Sierra Nevada mountain range.
Municipalities handed out sandbags to help residents ward off flooding and reminded people to prepare for the storms by stocking emergency supplies, routines that had become unfamiliar amid the years of drought.
Supermarkets were emptied of bottled water on Wednesday night. At a SaveMart supermarket in Sacramento, shoppers combed the aisles for prepared foods that could be served without cooking in the event of an extended blackout.
Wind gusts peaking at 50 mph (80 kph) were recorded on the Sonoma County coast north of San Francisco, the National Weather Service said early Thursday.