The Latest on the wintry weather in the U.S. (all times local):
Northern California and southern Oregon residents are bracing for a “bomb cyclone” weather phenomenon that’s expected at one of the busiest travel times of the year.
The National Weather Service says the storm expected Tuesday into Wednesday could be like nothing experienced in the area for 20 years.
Wind gusts of 75 mph (120 kph) are expected in some areas and waves of 35 feet (10.6 meters) or more could slam the coast.
Mountain passes in northern California and southern Oregon could get up to two feet (0.6 meters) of snow.
The center of the low-pressure system is expected to make landfall late Tuesday afternoon between Crescent City, California, and Brookings, Oregon.
A “bomb cyclone” forms when air pressure drops by 24 millibars in a 24-hour period.
Forecasters say this storm’s air pressure has dropped even more quickly than that.
Among those spending the night at Denver’s airport as a big snowstorm hit Colorado was Air Force Academy cadet Sadie Luhman, who was trying to get to Chicago for Thanksgiving.
Luhman told KCNC-TV that she left the academy near Colorado Springs late Monday to drive to the airport in the hope of beating the storm but ended up traveling right in the middle of it.
The trip took about three hours. That’s more than twice the normal driving time and she arrived at 1 a.m. Tuesday, 10 hours before her scheduled flight.
The airport has received 9.5 inches (24 centimeters) of snow from the storm so far. About 30 percent of its average daily 1,600 flights were cancelled.
An approaching storm forecast to dump heavy snow in the region has accelerated the seasonal closing of the highway to the North Rim of the Grand Canyon by a few days.
The Arizona Department of Transportation on Tuesday announced the closure of State Route 67, a 43-mile (69-kilometer) paved route between U.S. 89A at Jacob Lake and the North Rim.
The National Weather Service forecasts 27-35 inches (69-89 centimeters) of snow will fall on the North Rim from Wednesday night through Saturday morning.
SR 67 normally closes Dec. 1 but it can close earlier when weather conditions warrant.
It reopens in the spring, usually around mid-May.
About 1,100 travelers stranded by heavy snow and high winds spent the night camped out at Denver’s airport.
Hundreds of flights were canceled because of the storm that was still dumping snow on the city Tuesday.
Airport spokeswoman Alex Renteria says the workers handed out blankets, diapers, formula and toothbrushes and toothpaste to people who missed flights, including Air Force Academy cadets trying to get home for Thanksgiving.
About 30 percent of the airport’s daily average of 1,600 flights have been cancelled.
Crews were working to keep the airports’ runways cleared and airport officials were hopeful operations could return to normal Tuesday afternoon.
Forecasters are warning of “difficult to impossible travel conditions” across much of northern Arizona later this week as a storm dumps about 2 feet (0.6 meters) of snow along an area including Interstate 40.
Elsewhere in Arizona’s high country, approximately 1 foot (0.3 meter) of snow is expected.
The National Weather Service’ office in Flagstaff says travel conditions will start to deteriorate Wednesday night, followed by the heaviest snowfall Thursday through Friday morning.
The weather service said snow showers will become scattered late Friday but that traffic conditions will remain dangerous until Saturday.
A storm that has dumped heavy snow in Colorado and Wyoming has forced airlines to cancel hundreds of flights during the busy Thanksgiving week travel period and has made driving impossible in some areas.
Some government offices in the Denver area and in Cheyenne, Wyoming are closed Tuesday and about 7 inches (18 centimeters) of snow had fallen at Denver International Airport by Tuesday morning.
More snow was expected, forcing the cancellation of about a third of the airport’s average 1,600 daily flights.
More than 2 feet (60 centimeters) of snow has fallen in northern Colorado and about a foot (30 centimeters) fell in southern parts of Wyoming.
Heavy snow and gusty winds forced the closures of long stretches of Interstates 70 and 76 in Colorado and Interstate 80 in Wyoming.
Officials say parts of Interstate 80 were buried under snow drifts of up to 4 feet (1.2) meters.
— This version corrects that Denver’s airport averages 1,600 flights daily, not 1,500.
Thanksgiving travel is an ordeal under the best of circumstances, and a one-two punch of bad weather threatens to make it even more exhausting.
Airlines prepared to deal Tuesday with a forecast for heavy snow in Denver, canceling flights ahead of time and offering customers a chance to reschedule without racking up standard ticket-change fees.
As that front moves through the Great Lakes and the Northeast later in the week, forecasters say another storm will crash into the West Coast, possibly fouling flights and making driving treacherous.
The AAA auto club says more than 55 million people will travel at least 50 miles (81 kilometers) from home over Thanksgiving, and the Transportation Safety Administration is predicting record numbers at airports.