Waves at North Avenue beach, in Chicago on Monday, October 29, 2012.

Officials had a simple warning as the Chicago area braced for high winds and waves from a massive storm along the East Coast.

"Stay off the lake folks," said Gary Schenkel, executive director of Office of Emergency Management and Communication. "Lake winds are going to be 50 to 60 mph. Waves could exceed the 24-foot mark. So please stay off the lake ... This could be a very dangerous situation."

The National Weather Service has issued a lakeshore flood warning for the Chicago area from 1 a.m. Tuesday until 4 p.m. Wednesday and a high wind warning from 7 a.m. to 7 p.m. Tuesday for Lake and Porter counties in Indiana because of the storm on the East Coast, where Hurricane Sandy is on track to collide with a wintry storm moving in from the west and cold air streaming down from the Arctic.

As of 8:30 p.m., no substantial delays are reported at O’Hare or Midway Airports, according to a statement from the Chicago Department of Aviation.

Airlines have canceled nearly 500 flights at O'Hare, most of which were scheduled to and from the East coast, according to the statement.

Meanwhile, airlines at Midway have canceled more than 100 flights, the statement read.

Chicago Park District officials said they have been securing beaches and plan to close the lakefront trail from North Avenue to Ohio Street beginning at 11 p.m. today.

The CTA is prepared to reroute buses as necessary, depending on the waves, Schenkel said. Throughout Tuesday, outdoor concessions on Navy Pier and the ferris wheel will be closed.

For now, the city does not plan to close Lake Shore Drive, Schenkel said. "We do not want to close Lake Shore Drive," Schenkel said. "We're prepared to at any time should there be an event out there."

National Weather Service meteorologist Richard Castro advised waterfront high-rise residents to secure items on their balconies, and joggers and bicyclists should avoid the lake shore.

Due to high waves, the bike path was closed along Lake Shore Drive from Oak to Ohio Streets, authorities said. 

"The fact we're seeing impact in the wind out here in the Midwest — the magnitude of this storm is really rare," Castro said.

Sandy is so large, he added, that it's also preventing the cool weather system over Chicago from moving out. Temperatures aren't expected to rise higher than 50 degrees through at least Thursday.

But Chicago's troubles are minuscule compared to those on the coast.

By midday, the storm was picking up speed and was expected to blow ashore in New Jersey or Delaware by the evening, hours sooner than previously expected. Forecasters warned it would combine with two other weather systems — a wintry storm from the west and cold air rushing in from the Arctic — to create an epic superstorm.

From Washington to Boston, subways, buses, trains and schools were shut down and more than 7,000 flights grounded across the region of 50 million people. The New York Stock Exchange was closed. And hundreds of thousands of people were under orders to move to higher ground to await the storm's fury.

President Barack Obama and Mitt Romney suspended their campaigning with just over a week to go before Election Day.

At the White House, the president made a direct appeal to those in harm's way: "Please listen to what your state and local officials are saying. When they tell you to evacuate, you need to evacuate. Don't delay, don't pause, don't question the instructions that are being given, because this is a powerful storm."

Authorities warned that New York City and Long Island could get the worst of the storm surge: an 11-foot onslaught of seawater that could swamp lower Manhattan, flood the subways and damage the underground network of electrical and communications lines that are vital to the nation's financial capital.

Because of Sandy's vast reach, with tropical storm-force winds extending almost 500 miles from its center, other major cities across the Northeast — Washington, Baltimore, Philadelphia and Boston — also prepared to for the worst.

"The days ahead are going to be very difficult," Maryland Gov. Martin O'Malley said. "There will be people who die and are killed in this storm."

Sheila Gladden evacuated her home in Philadelphia's flood-prone Eastwick neighborhood and headed to a hotel.