ToplineBad weather is throwing a wrench into Tuesday air travel, with more than 6,500 disrupted flights and several ground stops at East Coast hubs—as airlines offer waivers allowing customers to rebook without incurring a fee.The National Weather Service predicts severe weather on the East Coast with the potential for flooding and tornadoes.NOAA/NWSKey FactsAs of 3:45 p.m. EDT on Tuesday, over 4,600 flights were delayed and 1,900 canceled in the U.S., according to data from FlightAware.There were ground stops Tuesday afternoon at Boston Logan, New York’s LaGuardia, Newark Liberty, Washington’s Reagan National and Dulles, Baltimore/Washington and Philadelphia airports, according to the Federal Aviation Administration (FAA) National Airspace dashboard.Airports reporting triple-digit flight cancellations Tuesday afternoon included John F. Kennedy, LaGuardia, Newark, Boston, Philadelphia and Reagan National. Airlines reporting triple-digit cancellations include Republic Airways (regional carrier with contracts with American Airlines, Delta Air Lines and United Airlines), Southwest Airlines, JetBlue Airways, Endeavor Air (subsidiary of Delta), American, Delta and PSA Airlines (owned by American).Key BackgroundThunderstorms and flash flooding are expected from the Mid-South into the Northeast Tuesday, according to the latest National Weather Service forecast. “Severe wind gusts and flash flooding are expected to be the main hazards” while “severe hail and a few tornadoes are also possible.” Airlines Issue Travel WaiversMajor carriers have issued travel waivers allowing passengers scheduled to fly Tuesday in or out of impacted airports to rebook at no extra cost. American Airlines has a travel alert covering nine airports on the East Coast, while Delta Air Lines’ travel advisory also covers nine airports. United Airlines has issued a travel alert covering eight airports and Southwest Airlines has an advisory for passengers traveling through five airports. JetBlue Airways has an alert covering customers traveling Tuesday or Wednesday through 11 airports.TangentMost flight disruptions in the U.S. are weather-related. Airlines are not required to provide accommodations, meals or monetary compensation if disruptions are beyond their control. Many travel insurance policies provide coverage if a trip is significantly impacted by a weather-related flight cancellation or an extended delay. Benefits will be noted in the policy as trip cancellation, trip interruption, travel delay, extension of coverage or missed connection coverage. But note that in most cases the traveler must have purchased the policy before the storm was announced and forecasted to impact the trip.What to Watch For If Flying TuesdayTravelers ticketed to fly Tuesday may encounter flight delays and cancellations, even if they are not traveling through areas impacted by the storms. Flights in late afternoon are statistically more likely to be disrupted, as flight delays and cancellations in the morning tend to create a domino effect, causing a backlog that grows as the day wears on.Further ReadingJUST IN: NOAA Provides Updates On Growing Tropical Depression Off Southern Coast Of US (Forbes)