Storm grounds about 15% of all Tuesday flights in U.S.

Last update: 7:15 p.m. ET.

About 15% of the nation's flights were grounded Tuesday as airlines kept their planes out of the path of a major Northeast snowstorm. Airlines also were waiving rebooking fees -- with conditions -- for customers looking to change their flights.

Even though snowfall totals fell short of expectations in New York City and Philadelphia, few flights remained on the schedule Tuesday.

Airlines preemptively canceled most of those flights on Sunday and Monday, when forecasts called for up to three feet of snow and authorities enacted travel bans and announced transit shutdowns.

Most flights also were canceled Tuesday in Boston and throughout New England, where snowfall totals appeared to live up to the hype.

Overall, about 4,740 had been canceled nationwide as of 7:15 p.m. ET, according to flight-tracking service FlightAware. That total represented about 15% of all of Tuesday's scheduled airline flights in the United States, FlightAware says.

The storm's three-day cancellation tally now stands at about 8,180, with Tuesday cancellations coming on top of the 2,866 that were grounded Monday.

And already for Wednesday, airlines have canceled about 580 flights. The bulk of those Wednesday cancellations are at the Boston, New York and Philadelphia airports.