A city plow drives past some tulips during a spring snowstorm in Milwaukee. Another spring snowstorm spread Thursday across the northern U.S., closing schools and grounding airline flights.

Chicago ? More snow fell across the northern states Thursday as a deadly storm that already had grounded hundreds of flights, postponed a baseball game and disappointed those longing for the warmth of spring moved eastward.

A jet trying to land early Thursday at Traverse City, Mich., skidded 50 feet off a runway in the heavy snow. The plane remained upright, and the 46 passengers and three crew members were unhurt, Pinnacle Airlines spokesman Phil Reed said.

Six deaths elsewhere were blamed on the slick conditions.

The worst of the storm blew into the Northeast, where the National Weather Service posted winter storm warnings Thursday for much of northern New England, forecasting up to a foot of snow through today in some areas.

In Vermont, Mount Snow, a ski area that had closed for the season, decided to reopen for the weekend after getting 5 inches of new snow by midday Thursday.

“Better late than never,” said Mount Snow spokesman Chris Lenois. “There’s no bare spots on the mountain. I’m looking out my window and it’s all white.”

Forecasters expected up to 10 inches in parts of New Hampshire. Up to 8 inches were expected in central Maine, already hit once this month with a storm that knocked out power across the state.

Parts of the Midwest received more than 9 inches of snow Wednesday and Thursday, with another inch or more expected as the snow tapered off during the day.

“I think we are all cranky about the weather,” said Pat Rowe, spokeswoman for Milwaukee’s General Mitchell International Airport, which had delays and cancellations Wednesday.

In Chicago, more than 550 flights were canceled Wednesday at O’Hare International Airport because of poor visibility, though operations were mostly back to normal Thursday, said city aviation spokesman Gregg Cunningham.

Colorado was expecting the worst of the storm today, when up to 18 inches of snow was expected to fall in the Rocky Mountain foothills.

Denver International Airport brought contractors in early to help move snow. United Airlines canceled 80 flights Thursday night and 40 this morning ahead of the storm and was rebooking passengers, spokesman Jeff Kovick said.

Milwaukee broke a snowfall record for the date with 7 inches; the previous record of 3.2 inches was recorded in 1997. The town of Taylor, in west-central Wisconsin, had 9.5 inches. North Dakota and South Dakota got about 7 inches of snow.

“It’s kind of flying sideways,” hardware store owner Harvey Neu said in Menomonee Falls, Wis. “It’s not like a gently falling snowfall. It’s more of a get-out-of-my-face type of thing.”