Millions of Americans were placed on alert Thursday as a significant tornado threat loomed over a large stretch of the Mid-Atlantic. The National Weather Service (NWS) issued a Tornado Watch for portions of Maryland, Virginia, New Jersey, Pennsylvania, and Delaware, including Washington D.C. The alert is scheduled to remain active until 10 p.m. ET on Thursday.
The affected area spans the Washington-Baltimore-Philadelphia commuter corridor and encompasses communities around the Chesapeake Bay, Delaware Bay, and the lower Delaware River. The NWS advised residents to keep emergency notifications active, monitor local forecasts, and identify the safest location within their homes in anticipation of the storms.
A tornado watch signifies that atmospheric conditions are favorable for tornado development, but it does not confirm the presence of a tornado. The NWS emphasized that if a tornado warning is issued, individuals should immediately seek shelter in a basement, storm shelter, or an interior room on the lowest floor, away from windows. Those in mobile homes, vehicles, or outdoors were urged to plan their move to a sturdy building before storms arrive.
The NWS alert covers 39 counties and seven independent cities across the five states, along with the entirety of Washington D.C. Maryland has the broadest impact, with 19 counties included, stretching from the Washington suburbs and Baltimore region to Southern Maryland and the Eastern Shore. Baltimore City is also within the watch area.
In Virginia, the watch includes Arlington, Fairfax, King George, Prince William, and Stafford counties, as well as the independent cities of Alexandria, Fairfax, Falls Church, Fredericksburg, Manassas, and Manassas Park. This brings the threat to the densely populated northern Virginia suburbs and communities along the Interstate 95 corridor.
Five southeastern Pennsylvania counties are under the watch: Bucks, Chester, Delaware, Montgomery, and Philadelphia. In New Jersey, the affected counties are Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester, and Salem, extending from the Philadelphia suburbs to the Jersey Shore.
All three Delaware counties—New Castle, Kent, and Sussex—are included in the watch. The alert also extends to 21 coastal and tidal water zones, warning boaters of potentially rapidly deteriorating conditions. Affected waterways include sections of Delaware Bay, the Chesapeake Bay, the tidal Potomac River, the Patapsco River, and Baltimore Harbor, among others.
In addition to tornadoes, the NWS indicated that scattered severe thunderstorms and excessive rainfall are possible across the Mid-Atlantic on Thursday, posing risks of damaging winds and isolated flash flooding. The service reiterated that a watch provides time for preparation, while a warning signals that immediate action is necessary.
Preparations recommended by the NWS include charging mobile phones, ensuring emergency alerts are enabled, and bringing loose outdoor items inside if safe. Families are advised to designate a windowless interior room, basement, or storm shelter and pre-stock it with essential supplies like shoes, helmets, and flashlights. Residents of mobile homes are particularly cautioned to arrange for accommodation in a substantial building, as manufactured homes offer minimal protection against tornado-force winds. NWS forecast offices serving Baltimore and Washington, Wakefield, Virginia, and Philadelphia and Mount Holly, New Jersey, are coordinating to issue more specific warnings as storms develop.