A Frontier airplane at O’Hare International Airport in Chicago on Thursday. (Nam Y. Huh/The Associated Press)

The Northeast is bracing for the arrival of a major winter storm, while steady waves of snow have already coated swaths of the Midwest.

For anyone traveling on Thursday, Friday and into the weekend, all of this winter weather means one thing: delays. Lots and lots of delays.

More than 1,700 flights had been canceled as of 3:15 p.m. on Thursday, while more than 4,500 delays have been reported, according to FlightAware.

O’Hare International Airport in Chicago was the hardest hit, with hundreds of cancellations and delays for flights heading to or from that key hub. Newark Liberty International, LaGuardia and Cleveland Hopkins International airports were also seeing numerous cancellations and delays. In addition, scores of flights scheduled to go to or from Newark and LaGuardia on Friday have already been canceled.

Flight delays at hubs like those around New York and Chicago can have a ripple effect that impacts airports and travelers nationwide, creating problems just as many people are trying to get back to work and school following the recent holidays.

And the snow will also create problems along the stretch of Interstate 95 between Philadelphia and Boston, which could delay drivers trying to get through that span following any holiday trips. Amtrak announced that it is preparing for the storm by setting up equipment along the Northeast Corridor so it can quickly deal with any downed trees or damage to the electrical system. The rail agency will also have additional tree-trimming contractors and other staffers ready to respond to downed debris or any other issues that could arise.

UPDATE: Amtrak announced on Thursday afternoon that it will operate a modified schedule on Friday due to the snow. Acela and Northeast Regional trains will still run between Boston and Washington, but they will run less often, particularly in New England.

The Washington region is expecting brutal cold on Friday, while the latest forecast calls for up to three or potentially four inches of snow, reports Jason Samenow of the Capital Weather Gang. Still, some snow, sleet and rain had developed in the area on Thursday afternoon, which could create commuting problems when people head home. (Follow the Capital Weather Gang’s live updates here.)

New York is preparing for several inches of snow and blizzard-like conditions on Thursday and into Friday. Gov. Andrew M. Cuomo activated the state’s emergency operations center, warning drivers to expect the closures of major highways across the state. Bill de Blasio, who was just sworn in as mayor of New York, said the city is “100 percent ready” for the snowstorm.

Philadelphia is expecting between four and six inches of snow, with the majority of it arriving on Thursday night and during the early morning hours on Friday, possibly ending shortly before the morning commute begins there.

The forecasts are more dire for the Boston region, which is preparing for perhaps 10 to 14 inches of snow. Massachusetts Gov. Deval Patrick ordered all non-emergency employees to leave work at 3 p.m. on Thursday and activated the Massachusetts National Guard to help with storm response. Logan Airport in Boston is expecting reduced flight operations until at least Friday morning, if not later. The Massachusetts Port Authority, which owns and operates Logan, is urging travelers to contact their airlines for the latest flight information.

Airlines are already loosening their restrictions on changing flights. United announced that it would waive the change fees and any fare differences for travelers originally going through Boston, Chicago and the three New York area airports, among others, from Thursday through Sunday. US Airways, Delta and JetBlue similarly said they would waive change fees for travelers going through certain locations on Thursday or Friday, and Southwest Airlines has also announced that fees would be dropped for certain dates and cities.

Flight information shown at O’Hare International Airport in Chicago on Thursday. (Nam Y. Huh/The Associated Press)

This post has been updated. Most recent update: 4 p.m.