A prolonged winter storm that knocked out power to hundreds of thousands of customers in the Upper Midwest was continuing its assault on the region on Thursday, as portions of Southern California prepare for blizzard conditions, forecasters said.
More than 800,000 customers were without power early Thursday across Illinois, Indiana, Michigan and Minnesota, according to PowerOutage.us, which compiles data from utilities. More than 650,000 of those outages were in Michigan, where significant ice had accumulated on trees and power lines.
The weather was also affecting air travel. By Thursday morning, more than 730 flights were canceled within, into or out of the United States, according to FlightAware, a flight tracking website
In Southern California, some residents were preparing for an unusual weather scenario: a blizzard.
The National Weather Service in Los Angeles issued a winter storm warning for the mountains of Los Angeles, Ventura and Santa Barbara Counties until early Friday, warning of “extremely dangerous mountain conditions.” A rare blizzard warning, for the same areas, will take over from Friday through Saturday.
This isn’t the first blizzard warning from the Los Angeles National Weather Service office, but it has been decades since the last one. The forecast office’s historical records go back only to 2006, so its forecasters, more accustomed to issuing high surf advisories and flash flood warnings, were unsure of their last blizzard warning. However, after some sleuthing, they found one was issued on Feb. 4, 1989.
Forecasters in Los Angeles described the storm affecting that region beginning Thursday as a dangerous one, and they predicted up to seven feet of snow in areas more than 4,500 feet above sea level. Lesser amounts, between one and six inches, were expected in elevations of less than 2,500 feet. Areas along the coast and valleys could see up to five inches of rain.
The lower elevation snow will mean that this could be the largest amount of 24- to 48-hour snowfall seen in decades — likely since a 1989 snowstorm that snarled traffic — for the Ventura and Los Angeles County mountains, forecasters said.
“Everything is adding up for a major snow event,” said Andrew Rorke, a senior forecaster for the Weather Service office in Los Angeles.
A person standing in downtown Los Angeles can see a 10,600-foot peak that will typically have snow on it, Mr. Rorke said. By Saturday that snow will extend much farther down the mountain, showing more snow than a typical winter storm.
But don’t expect the Hollywood sign to be lost in a snow-covered hillside.
“The Hollywood Hills are saved from snow, but the San Gabriels behind the Hollywood sign are certainly not,” Mr. Rorke said.
Los Angeles is surrounded by mountains, and when they get heavy snow, passage through them shuts down.
The California Governor’s Office of Emergency Services issued a news release on Wednesday, detailing numerous ways that Californians should prepare for the storm, including collecting a bag with important documents, cash and medications. Officials also warned against using a gas stove or oven to heat a home.
In the Northeast, snow began falling on Wednesday and in some areas it was measurable. A winter storm warning was in effect for parts of Maine, New Hampshire, New York and Vermont.
In the Buffalo area, meteorologists expected mixed precipitation on Thursday with snow accumulations up to three inches and ice accumulations around a tenth of an inch. Farther east in Vermont, meteorologists said heavy snow would sweep most of the state, dumping up to 10 inches of snow.