We already have major weather-related airline delays at all three NYC airports, Boston, Philadelphia and San Francisco.
Now, a tornado watch has been issued until 10pm for rapidly developing thunderstorms in the Middle Atlantic States. These storms will further snarl air travel. Keep in mind, thunderstorms are also possible later at Atlanta, Chicago, and Milwaukee -- major airline hubs. This is a day I would suggest checking the "flight status" section of your airline's web site.
As with any tornado watch, people in the area should keep an eye on the weather and local weather advisories at the first sign of approaching thunderstorms. Know, in advance, where you will seek safety if a tornado warning is issued.
Note: I am at an American Meteorological Society meeting and cannot live-blog the storms.