Two powerful winter storms were hammering the West Coast and Midwest on Wednesday, shutting down highways and snarling travel plans on one of the nation's busiest travel days.
Weather watches, warnings and alerts were posted across much of the western half of the nation after a storm that had been a "bomb cyclone" began its westward march from the California coast late Tuesday, AccuWeather reported.
Hundreds of cars remained stranded Wednesday on Interstate 5 headed north from California into Oregon in the aftermath of the storm that dumped snow and created white-out conditions on both sides of the California-Oregon border.
As the skies cleared Wednesday, drivers reported being stuck for 17 or more hours in blizzard conditions and some spent the night in their vehicles.
Further south, winter storm warnings were in effect for the mountains near Los Angeles early Wednesday to early Friday with 6 to 12 inches of snow forecast for most mountains, except 12 to 24 inches for the San Gabriels, the National Weather Service in Los Angeles warned. "Expect significant travel delays and road closures with dangerous winter driving conditions."
Meanwhile, parts of the central U.S. remained under siege from a storm that delayed or canceled almost 1,000 flights in Denver alone. High winds and heavy snow forced a temporary shutdown of I-70 in parts of Colorado and across the border into Kansas. It reopened in Kansas, but the state Highway Patrol urged Kansans to stay off the roads.
"Stay put, doesn't look like fun," Trooper Tod Hileman warned.
As of late morning Wednesday, howling winds had already knocked out power to over 200,000 customers in the Midwest and Great Lakes regions, according to poweroutage.us. This included 18,000 in the Chicago metro area, where high winds knocked down power lines and poles.
And in the Deep South, residents in Louisiana and Mississippi were cleaning up from apparent tornadoes that struck overnight. Officials in Mississippi say eight to 10 houses were damaged in Star, a fringe suburb southeast of Jackson.
Damage was also reported from a separate storm near Baskin, Louisiana, a rural town southeast of Monroe.
The timing for the storms couldn't be much worse. AAA estimates that more than 55 million travelers planned to kick off the holiday season with a trip of 50 miles or more away from home this Thanksgiving. That would be the second-highest Thanksgiving travel volume since AAA began tracking in 2000.
About 50 million of them planned to drive, and Wednesday was forecast as the heaviest driving day. Even the East was not secure, with high winds forecast that could knock down trees and power lines.
"A powerful storm will shift from the Central Plains into the upper Midwest bringing a swath of heavy snow and damaging winds today," the National Weather Service said in an alert Wednesday. "Strong winds shift to the Northeast on Thanksgiving, which could impact celebrations."
The rare West Coast "bomb cyclone" swept into southern Oregon and northern California, bringing 100-mph wind gusts to the coast.
A bomb cyclone, or bombogenesis, occurs when a storm's central barometric pressure drops at least 24 millibars in 24 hours. (A millibar is a way of measuring air pressure.) The lower the pressure, the more powerful the storm.
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An all-time record low sea level pressure in the state of California was surpassed in Crescent City, California, according to NOAA's Weather Prediction Center.
Angela Smith said the Oceanfront Lodge, a hotel she manages in Crescent City in far Northern California, lost power briefly during rain and strong winds as the bomb cyclone blew ashore. She said the hotel is ready to withstand heavy downpours.
"It's blowing pretty good outside but because we're right on the coast, everything was built to ensure the safety of people," Smith said.
The Weather Prediction Center, in a weather summary, called it "a tale of two storms for Thanksgiving week. The first crosses the Central Plains into the Upper Midwest into Wednesday, bringing heavy snow and strong winds. The second (spreads) heavy snow, heavy rain and strong winds across the West."
Contributing: The Associated Press
This article originally appeared on USA TODAY: Thanksgiving weather: Bomb cyclone brings snow to California, Colorado