The storms moved east from Mississippi, Alabama and northwestern Arkansas, where at least seven people were injured, two critically, when a tornado touched down on Wednesday.
Mayor Doug Sprouse of Springdale, Ark., the town where the seven people were injured, declared an emergency there on Wednesday. “Many residents have been displaced from their homes and numerous businesses have reported significant damages,” Mr. Sprouse said in a statement.
The Weather Service said the line of storms were continuing to move east on Thursday and could cause severe thunderstorms and isolated tornadoes from Florida to New England.
Bob Oravec, a lead forecaster for the Weather Service, said that on Thursday, “there is a chance for severe weather from the Florida Panhandle across pretty much the entire East Coast.”
Parts of the Carolinas, Maryland and Virginia were under tornado watches Thursday evening. The National Weather Service also said that scattered severe thunderstorms would move through the Northeast. Portions of Maryland, Pennsylvania, Virginia, West Virginia and Washington, D.C., were instructed to stay on alert for strong winds, hail and tornadoes until 10 p.m., while parts of Delaware, New Jersey and New York should brace for winds up to 70 miles per hour and possibly “a tornado or two” until midnight.
The Weather Service advised people in the affected areas to secure loose items and warned that there could be power outages and downed trees.
More than 15,000 customers were without power in Virginia Thursday evening, as well as 13,000 customers in Mississippi, 11,000 in North Carolina and 11,000 in Tennessee, according to PowerOutage.US, a website that aggregates data from utilities.
Claire Fahy contributed reporting.
