FORESTVILLE, Calif. (AP) -- A major storm moving through Northern California on Thursday toppled trees and dropped heavy snow and record rain after damaging homes, killing two people and knocking out power to hundreds of thousands in the Pacific Northwest. Forecasters warned that the risk of flash flooding and rockslides would continue, and scores of flights were canceled at San Francisco's airport.
In Washington, more than 320,000 people -- most of them in the Seattle area -- were still without power as crews worked to clear streets of electrical lines, fallen branches and debris. Utility officials said the outages, which began Tuesday, could last into Saturday.
Meanwhile on the East Coast, where rare wildfires have raged, New York and New Jersey welcomed much-needed rain that could ease the fire danger for the rest of the year.
The National Weather Service extended a flood watch into Saturday for areas north of San Francisco as the region was inundated by the strongest atmospheric river -- a long plume of moisture that forms over an ocean and flows through the sky over land -- this season. The system roared ashore Tuesday as a "bomb cyclone," unleashing fierce winds.
Communities in Washington opened warming centers offering free internet and device charging. A number of medical clinics closed because of power outages.
"I've been here since the mid-'80s. I haven't seen anything like this," said Trish Bloor, who serves on the city of Issaquah's Human Resources Commission, as she surveyed damaged homes.
Up to 16 inches (about 41 centimeters) of rain was forecast in southwestern Oregon and California's northern counties through Friday. The Sonoma County Airport, in the wine country north of San Francisco, received 6.92 inches (17.5 centimeters) Wednesday, breaking a record dating to 1998.
In nearby Forestville, one person was hurt when a tree fell on a house. Small landslides were reported across the North Bay region, including one on State Route 281 on Wednesday that caused a car crash, according to Marc Chenard, a weather service meteorologist.
Rain slowed somewhat, but "persistent heavy rain will enter the picture again by Friday morning," the weather service's San Francisco office said on the social platform X. "We are not done!"
Dangerous flash flooding, rockslides and debris flows were possible, especially where hillsides were loosened by recent wildfires, officials warned. Scott Rowe, a hydrologist with the weather service in Sacramento, said that so far the ground has been able to absorb the rain in California's Butte and Tehama counties, where the Park Fire burned over the summer.
"It's not necessarily how much rain falls; it's how fast the rain falls," Rowe said.
Northern Mendocino and southern Humboldt counties received between 4 and 8 inches (10 and 20 centimeters) of rain in the last 48 hours, and similar amounts were expected over the next 48 hours, forecasters said. Wind gusts could top 50 mph (80 kph).
The storm system, which first hit the Pacific Northwest on Tuesday, reached the status of " bomb cyclone," which occurs when a cyclone intensifies rapidly.
A winter storm watch was in place for the northern Sierra Nevada above 3,500 feet (1,066 meters), with 15 inches (38 centimeters) of snow possible over two days. Wind gusts could top 75 mph (121 kph) in mountain areas, forecasters said.
Sugar Bowl Resort, north of Lake Tahoe near Donner Summit, picked up a foot (30 centimeters) of snow overnight, marketing manager Maggie Eshbaugh said Thursday. She said the resort will welcome skiers and boarders on Friday, the earliest opening date in 20 years.
"And then we're going to get another whopping of another foot or so on Saturday, so this is fantastic," she said. Another popular resort, Palisades Tahoe, is also opening Friday, five days ahead of schedule, according to its website.
The storm already dumped more than a foot of snow along the Cascades in Oregon by Wednesday night, according to the weather service. Forecasters warned of blizzard and whiteout conditions and nearly impossible travel at pass level.
Falling trees struck homes and littered roads across western Washington, killing at least two people. A woman in Lynnwood was killed when a large tree fell on a homeless encampment, and another in Bellevue died when a tree fell on a home.
More than a dozen schools closed in the Seattle area Wednesday, and some opted to extend the closures through Thursday.
In Enumclaw, east of Seattle, residents were cleaning up after their town clocked the highest winds in the state Tuesday night: 74 mph (119 kph).
Resident Sophie Keene said the powerful gusts caused transformers to blow out around town. "Things were exploding, like, everywhere," Keene told the Seattle Times. "Like the transformers over by the park. One blew big, it looked like fireworks just going off."
Ben Gibbard, lead singer of the indie rock bands Death Cab for Cutie and Postal Service, drove from his Seattle neighborhood Thursday morning to the woods of Tiger Mountain for his regular weekday run, but there were too many trees blocking the trail.
"We didn't get hit that hard in the city," he said. "I just didn't assume it would be this kind of situation out here. Obviously you feel the most for people who had their homes partially destroyed by this."
In California, there were reports of more than 20,000 power outages on Thursday.
Only 50 vehicles per hour were allowed through part of northbound Interstate 5 from 10 miles (16 kilometers) north of Redding to 21 miles (34 kilometers) south of Yreka due to snow, according to California's Department of Transportation.
Transportation officials also shut down a two-mile (3.2 kilometer) stretch of the famed Avenue of the Giants, a scenic drive named for its towering coast redwoods, due to flooding.
About 150 flights were delayed and another two dozen were canceled early Thursday at San Francisco International Airport after hundreds of delays and dozens of cancelations the previous day, according to tracking service FlightAware.
Parched areas of the Northeast got a much-needed shot of precipitation Thursday, providing a bit of respite in a region plagued by wildfires and dwindling water supplies. More than 2 inches (5 centimeters) of rain was expected by Saturday morning in areas north of New York City, with snow mixed in at higher elevations.
"Any rainfall is going to be significant at this point," said Brian Ciemnecki, a weather service meteorologist in New York City, where the first drought warning in 22 years was issued this week. "Is it going to break the drought? No, we're going to need more rain than that."
Har reported from San Francisco, and Weber from Los Angeles. Associated Press writers Hallie Golden and Gene Johnson in Seattle; Martha Bellisle in Issaquah, Washington; Sarah Brumfield in Washington, D.C.; and Michael Hill in Albany, New York, contributed.
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