Airlines have already axed more than 1,700 Thursday flights

Latest update: 8:40 p.m. ET.

Airlines have already grounded more than 2,015 flights for Thursday as a nightmare stretch of air travel pushed into a second week.

That's on top of the more than 1,745 flights that were canceled nationwide on Wednesday, as of 8:40 p.m. ET, according to flight-tracking service FlightAware. Another 3,790 flights had been delayed Wednesday.

More broadly, more than 17,000 flights have been canceled and a whopping 52,600 delayed since the latest string of successive storms began to disrupt air travel last Saturday (Feb. 21).

This week will offer little relief as the latest storm was expected to snarl flights into Friday morning. Already for Thursday, about 1,200 flights had been preemptively grounded. That figure was likely to keep growing as a half-foot of snow or more was forecast from the Ohio Valley into the mid-Atlantic, where flights could be snarled at busy airports in Philadelphia, Washington and -- possibly -- the New York City area.

As with previous storms, airlines waived change fees for customers ticketed to fly into airports experiencing poor weather. The policies varied by airline, though they generally allowed customers to make one change without paying the customary change fee.

Dallas/Fort Worth bore the brunt of cancellations for Wednesday and had the second-most for Thursday. More than 635 flights had been canceled there for Wednesday and another 345 already for Thursday as the threat of icy weather looms for North Texas. Those cancellation tallies account for about 30% of the airport's Wednesday schedule and about 20% of Thursday's, according to FlightAware's calculations.

Elsewhere, Wednesday's cancellations were spread across a number of airports from the Great Plains into the Northeast.

A number of big airports were affected, with anywhere from three-dozen to more than 160 cancellations reported at the following airports as of 8:40 p.m. ET: Newark Liberty, Philadelphia, New York LaGuardia, Washington Reagan National, Charlotte, Chicago O'Hare, Houston Bush Intercontinental, Dallas Love, Atlanta, and Oklahoma City and Washington Dulles.

For Thursday, Philadelphia had the highest number of preemptive delays, with about 385 cancellations -- representing more than a third of its schedule. Newark, Washington Reagan National and New York LaGuardia and Washington Dulles also saw preemptive cancellation tallies into the hundreds. More than 20 other airports were already counting cancellations by the dozens for Thursday.