Ahead of the busiest travel day of the year, heavy snow is falling across Colorado roadways and runways on Tuesday, with 10 to 14 inches already being reported in some parts of the state.
The Denver area has seen about 10 inches of snow and could see up to 14 inches.
A blizzard warning is in effect east of Denver for blowing snow and whiteout conditions.
Over 470 flights have been canceled at Denver International Airport due to the severe weather.
More than 1,100 passengers were stranded at Denver's airport Monday night as 4 inches of dry snow took over the taxiway.
Three out of six runways are now open and an airport spokesperson expects more runways to open later in the day.
Crews early Tuesday rushed to the scene of a deadly car crash in the mountains near Vail, more than two hours west of Denver.
The accident closed Interstate 70 in both directions, said the Colorado State Patrol.
After barreling through Denver, the storm will move into the Midwest Tuesday night, bringing heavy snow to northern Kansas, Nebraska and into Minnesota.
From Tuesday night to Wednesday morning -- which will be the biggest Thanksgiving travel day -- Minneapolis will get the brunt of the heavy snow. Seven to 12 inches of snow is possible with winds gusts up to 35 mph, creating very difficult travel on the road and in the air.
More than six inches of snow is possible from Kansas to northern Michigan through Wednesday morning.
Through the day on Wednesday, the snow will continue to push across the northern tier of the Great Lakes, from northern Wisconsin to Michigan and eventually into parts of northern New England.
Heavy rain is possible on Wednesday morning from Detroit to Atlanta, with just some scattered rain showers across the Northeast Wednesday afternoon and evening.
Then on Thanksgiving, although it will be dry, wind gusts could reach 30 to 50 mph from Washington, D.C., to New York to Boston, potentially causing problems for the Thanksgiving Day parade in New York City.
(MORE: What every motorist needs to know about driving in snow)The decision whether to fly the giant balloons will be a "game day decision," NYPD Chief Rodney Harrison said Tuesday.
Wind speed devices will help determine which balloons can soar at what height.
"We have people from all around the world. Safety is paramount," Harrison said.
Meanwhile, a second storm is barreling toward the West Coast Tuesday.
Heavy snow is developing from Oregon to California's Sierra Mountains. California could see 1 to 3 feet of snow.
Heavy rain -- and possibly flooding -- is expected to move from San Francisco Tuesday night down through Los Angeles on Wednesday.
(MORE: Cave Fire erupts in Santa Barbara County, scorching 4,200 acres)Rain along the California coast could reach 1 to 2 inches and gusty winds are expected to climb to 50 to 80 mph. Thirty-foot waves are possible along the coast.
That storm will then move east, bringing a mix of heavy rain ice, and snow to the Southwest and Plains on Thanksgiving.
ABC News' Aaron Katersky, Mina Kaji and Matthew Vann contributed to this report.