Ben Mutzabaugh and Harriet Baskas

USA TODAY

Airlines have preemptively canceled about 3,000 flights as major winter takes aim at the East Coast. Blizzard warnings and up to two feet of snow are forecast for major cities like Washington and Baltimore while mid-Atlantic cities like Charlotte could be grounded by ice.

About 1,800 Friday flights had been canceled as of 8:15 p.m. ET on Thursday, according to flight-tracking service FlightAware. More than 650 of those were at Charlotte, where American said it would preemptively ground its entire schedule Friday ahead of icy and wintry weather there. Charlotte is American's second-busiest hub, and shutting it down for an entire day is sure to send disruptions around American's nationwide network. The flight cancellations did not yet appear to make it into FlightAware's tally of Friday cancellations.

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American also planned to suspend its entire Saturday schedule at Philadelphia, Washington National, Balitmore/Washington and Washington Dulles. Philadelphia and Washington National are two of American's most important hubs.

Beyond American, cancellations were hitting other airports. More than 250 flights -- or close to half of the entire's day schedule -- was grounded at Baltimore/Washington International (BWI). Another 250 were preemptively canceled at Raleigh/Durham, where that figure represented more than half of the day's schedule there.

Dozens of Friday cancellations were being reported Thursday evening at many other airports, including Washington Reagan National, New York LaGuardia, Atlanta, Dallas/Fort Worth, Washington Dulles, Chicago O'Hare and Chicago Midway.

Across the region, airports were positioning snow removal machines and checking their stranded passenger supplies while airlines are rebooking travelers, issuing change-fee waiver policies and preemptively canceling flights as a potent snowstorm churned toward the East Coast and spawned blizzard warnings for Washington, D.C, Baltimore and up past New York City,

Cancellations had even spread to Florida, where more roughly 50 Friday flights had already been grounded at both Orlando and Fort Lauderdale by early Thursday evening. Those cancellations were all but certain to be the rippled effect of problems looming to the north.

Even 1,160 Saturday flights had been preemptively grounded by as of 8:15 p.m. ET Thursday afternoon. More than 300 of those came at Baltimore/Washington (BWI) and appeared to be on Southwest, which is the largest carrier there. More than 275 Saturday flights at Newark and 260 at Washington Dulles also had been grounded by late Thursday. Other significant Saturday cancellation tallies were being reported at airports in Boston, Newark, Richmond, Va., and Raleigh.

But cancellation totals were only likely to escalate from the Carolinas into New England if forecasts of up to two feet hold true. It's possible that hard-hit metro areas like Washington, Baltimore and Philadelphia could even see all flight operations halted for substantial periods of time if the heavy snow and blizzard conditions arrive as forecast.

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Travelers flying Friday and Saturday should brace for major disruptions in the Northeast. But problems could ripple elsewhere, even to cities under calm weather. A flight from Houston to Los Angeles, for example, could become delayed or canceled if the aircraft or crew scheduled to fly it gets bogged down in snowy Washington, D.C.

This morning, most domestic airlines updated their travel alerts, in some cases adding new cities to the list and in others, extending the days the alert covers.

Here’s the latest round-up of updated advisories from airlines:

Alaska Airlines is allowing travelers to change, postpone or cancel travel plans for tickets purchased on or before Jan. 20 for travel Jan. 22-24 to or from Baltimore/Washington International Airport (BWI), Boston Logan International Airport (BOS), Newark (EWR), New York JFK, Philadelphia International Airport (PHL), and Washington’s Dulles (IAD) and Reagan National (DCA) airports. The carrier will waive change fees and the difference in ticket price if new travel is booked and completed by Jan. 27, 2016.

In a travel alert updated Thursday morning, American Airlines relaxes change-fee policies for travel to/from or through more than 40 East Coast airports for passengers traveling on American and American Eagle flights Jan. 21-24 who rebook travel to the same city pairs, in the same class of service by Jan. 27, 2016.

Delta Air Lines’ Northeast Winter Weather advisory, updated this morning, applies now to more than 30 airports and reminds passengers that if their flights are canceled or significantly delayed, they are entitled to a refund.

For travelers with flights scheduled Jan. 24-26, the airline is allowing a one-time, fee-free change if the ticket is reissued on or before Jan. 27, 2016, and rebooked travel begins no later than Jan. 27.

Frontier Airlines’ storm alert covers travel from Jan. 21-25 to/from and through Philadelphia, Trenton-Mercer, N.J. (TTN), New York LaGuardia (LGA), Washington’s Dulles and Reagan National airports, Charlotte, N.C. (CLT), Raleigh-Durham, N.C. (RDU) and Greensboro, N.C. (GSO).

Passengers who purchased tickets on or before Jan. 19 may make one fee-free change and rebook for travel that must be completed by Jan. 31, 2016. Refunds will be issued for canceled flights.

This morning JetBlue updated its Winter Storm Jonas alert for the Mid-Atlantic and the Northeast.

In the Mid-Atlantic the airline is waiving change/cancel fees and the difference in airfare for customers with booked travel for Jan. 22-24, to or from BWI, Charlotte, N.C., Raleigh-Durham, N.C., Richmond, Va. (RIC) and Washington’s Dulles and Reagan National airports.

The airline’s alert says customers may rebook flights for travel through Jan. 29, 2016, and that customers with canceled flights can opt for a refund instead.

In the Northeast, JetBlue’s alert covers ticketed travel from Jan. 23 through Jan. 24 to or from Boston, Hartford Springfield, Conn. (BDL), New York LaGuardia, JFK and Newark, Newburgh, N.Y. (SWF), Philadelphia, Providence, R.I. (PVD), Westchester County, N.Y. (HPN) and Worcester, Mass. (ORH).

Customers may rebook flights for travel through Jan. 29, 2016, instead. Customers with canceled flights may opt for refunds.

This morning Southwest Airlines spokeswoman Melanie Jones said the airline's Network Operations Control Center Team was “actively monitoring the track and intensity of the storm and will make adjustments to flight schedules, as necessary, including canceling flights.”

In the meantime, the airline is advising customers holding reservations for travel Jan. 21-24 to, from and through (currently) 17 airports, including BWI, Boston, Charlotte, Greenville/Spartanburg (GSP), Little Rock (LIT), Long Island Islip (ISP), Louisville (SDF), Memphis, Nashville, Newark, New York LaGuardia, Philadelphia, Providence, Raleigh/Durham, Richmond, Washington Dulles and Washington Reagan National that they are eligible to reschedule their flights in accordance with the carrier’s accommodation procedures.

United Airlines’ updated travel waiver advisory now covers airports in more than 35 cities for ticketed travel from Jan. 22 through Jan. 24. “The change fee and any difference in fare will be waived for new flights departing on or before Jan. 20-27, 2016, as long as travel is rescheduled in the same cabin (any fare class) and between the same cities as originally ticketed,” the carrier notes on its website.

Harriet Baskas reported from Seattle; Ben Mutzabaugh’s report comes from Tulum, Mexico.