Boston, severe thunderstorm practically over the airport.
New York, thunderstorms nearby and more approaching.
Philadelphia thunderstorms will be approaching from the west after 3pm EDT.
Now look at the current status of the air traffic control system. I've never seen this many areas shut down due to "lack of routes." What that means is that there are so many thunderstorms, the FAA's controllers can't find air space where planes can safely fly.
So, this time it isn't just the huge delays (more than 4 hours in some cases) at the airports themselves, if the airport clears planes still cannot take off because there is no safe airspace in which they can maneuver.
The severe thunderstorm watches have been extended even farther west (see below). I now predict people will be stuck in airports for days.
If you are in this mess or supposed to fly later today I urge you to review my Airline Survival Guide (free) to help you proactively handle this mess.