Severe Weather Team 2 Meteorologist Brian Monahan has your Wednesday morning forecast.

Thanksgiving weather: Canceled flights, snow and a ‘bomb cyclone’

Thousands of Americans stranded at airports

Heavy snows, reaching 30 inches in some areas, disrupted travel across the center of the nation Tuesday and threatened to make more trouble Wednesday as the Thanksgiving holiday approached.

Hundreds of flights were canceled, thousands of travelers were stranded at airports, and stretches of major highways were closed because of unsafe conditions and periods of poor-to-nonexistent visibility.

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At the same time, the Northwest was warned of a separate “bomb cyclone” storm blowing in from the Pacific Ocean that could sock that region with powerful winds and heavy precipitation.

»PHOTOS: Snow storms slams U.S. before Thanksgiving

Some coastal areas in Northern California and Oregon should brace for “stronger than hurricane-force winds,” the National Weather Service said, warning that the high winds could bring down power lines, rip branches from trees and threaten to push 18-wheelers and RVs off the roads.

»READ: Winter Thanksgiving storms bringing snow, rain, wind to U.S.

The foul weather scrambled plans during one of the busiest travel weeks of the year, when more than 55 million people were expected to hit the roads or take to the skies.

Almost 500 flights were canceled to and from Denver International Airport beginning late Monday, and hundreds of passengers were stranded at the airport overnight, as nearly a foot of snow fell on the Denver area by Tuesday morning.

»MORE: Record 31.6 million airline passengers expected over Thanksgiving travel period

A number of airlines, including American, Southwest and Delta, issued travel waivers, allowing passengers to change their flights without incurring fees.

Although a late November snowstorm is no surprise in the Rockies, the Plains and the upper Midwest, the severity of this one was notable. It dropped about a foot of snow on Cheyenne, Wyoming, beginning Monday afternoon, and was threatening the Minneapolis-St. Paul metropolitan area with its biggest November snowfall in nearly a decade.

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Areas in the Upper Peninsula of Michigan were expected to receive between 6 and 12 inches of snow Tuesday evening.

Kyle Fredin, a National Weather Service meteorologist in Denver, said Tuesday that the storm, which produced blizzard conditions and near-zero visibility as it blew across Colorado on Tuesday, should not be taken lightly: “We’re sending that message pretty firmly, that travel will be difficult, if not impossible across some routes.”

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Interstate 70, a major east-west highway, was closed in both directions near Denver on Tuesday.

The University of South Dakota, University of Wyoming and several colleges in the Minneapolis area canceled classes for the day to give students an early start on holiday travel. With snow blanketing Colorado, a number of local and state government offices there also shut down Tuesday.

»Travel weather: Check forecast for any US city

Strong winds knocked down trees and heavy snow forced the authorities to shut down major freeways in Northern California and Oregon as a winter storm barreled into the West on Tuesday evening.

The storm, driven by a strong jet stream, was expected to continue through Tuesday night and into Wednesday.

Forecasters said that winds were expected to reach 100 mph in places — well above hurricane force, which starts at 74 mph. The National Weather Service reported one wind speed reading of 93 mph Tuesday near Lake Tahoe.

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Marc Spilde, a meteorologist at the Weather Service station in Medford, Oregon, said the last time a comparable storm hit the region was Columbus Day in 1962.

“We really haven’t seen a storm system like this originating from where it is.”

The storm blanketed the Cascades and northern Sierras with heavy snow. Interstate 5, the major north-south highway through the region, was shut down in two areas in Northern California because of snow, according to the California Department of Transportation.

Pacific Power reported more than 2,700 customers without power in Oregon and almost 14,000 without power in California as of 10:30 p.m. Tuesday.

The storm was expected to fit the definition of a bomb cyclone, in which barometric pressure drops by at least 24 millibars in 24 hours. In this case, forecasters expect the pressure at the center of the storm to fall by 50 millibars, to 970 from 1,020.

Differences in air pressure are what power a storm’s winds, “so this drop is very significant, very large,” Spilde said.

Areas of the East Coast can expect some wet and windy weather, with heavy snow in northern New England and northern parts of Maine later in the week.

Showers on Wednesday night and Thursday are expected to be accompanied by winds reaching between 20 and 30 mph, with gusts of 40 mph.

While such weather is not uncommon at this time of year, it may rain on some Thanksgiving Day parades. And operations at some of the nation’s busiest airports could be affected by the rain moving through the region, said Dean Iovino, a National Weather Service meteorologist in Mount Holly, New Jersey.

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