Weather-related headaches continued to dog the American traveller. That's how it's been again on Wednesday and that's how it is already shaping up for Thursday, too.

Nearly 1,100 flights had been grounded nationwide and another 600 delayed as of 10:30 a.m. ET. Those numbers were likely to grow.

That was just for Wednesday. More than 275 flights for Thursday had already been preemptively canceled as of Wednesday morning.

All these are happening as yet another round of winter weather disrupts flights over large parts of the country. Southwest temporarily grounded 128 Boeing 737s - about one-fifth of its fleet - Tuesday night on concerns about missed inspections. The planes have since been cleared to keep flying, but not before Southwest canceled about 90 flights from Tuesday into Wednesday.

With the latest cancellations, airlines have now grounded more than 6,700 flights since Saturday, when the first of the latest set of winter storms began disrupting air travel.

For Wednesday, the worst problems were in Texas and the Southeast, where snow and ice were possible across large parts.

Among the airports affected: Atlanta's Hartsfield-Jackson International, the world's busiest airport. More than 480 flights - about 20% of the day's entire schedule - had already been grounded as of 10:30 a.m. ET.

Hartsfield is the biggest hub for Delta Air Lines and is also a major base for Southwest Airlines.

At Charlotte - a large hub for American and merger partner, US Airways - about 190 flights had been grounded as of 10:30 a.m. Up to six inches of snow was possible there later Wednesday, indicating the tally could grow.

There were more cancellations Wednesday at Dallas/Fort Worth that was both recovering from a storm that ended Tuesday and suffering the effects of a new one that arrived overnight into Wednesday.

Around 220 flights had been canceled there as of 10:30 a.m. ET, representing about 10% of the day's schedule.