You can swim through the air on the East Coast this afternoon. It’s a typical hot, muggy summer afternoon, and an approaching cold front is allowing this soupy air to explode skyward and trigger some nasty thunderstorms. It looks like the storms will arrive in the megalopolis just in time for rush hour, of course.

Every major city on the East Coast from Washington to Boston is under either a severe thunderstorm or tornado watch this evening, as there’s enough instability and wind shear in the atmosphere to trigger thunderstorms that can produce damaging winds, large hail, and even a couple of tornadoes. The greatest risk for tornadoes is up in New England from Boston north through Maine, while the threat is mostly winds and hail farther south along I-95.

It looks like the strongest storms are on their way toward the Philadelphia area right now—that squall line in south-central Pennsylvania is pretty mean looking, and it’s likely producing very strong straight-line winds as it trucks generally off toward the east.

New York City is currently under a severe thunderstorm watch, but it looks like the strongest storms are breaking north and south of the Big Apple. Keep an eye on the radar, though—the atmosphere is soupy enough that storms can pop up and start raging with little notice.

Here’s a look at the watches as of 4:30 PM; counties shaded in blue are under a severe thunderstorm watch, while counties shaded in red are under a tornado watch. Each watch is in effect until the strongest storms (or at least the threat for them) pass through the area.

If your location goes under a tornado warning, get to the lowest level of your home and put as many walls between you and the outdoors as possible. It provides more opportunities to stop the debris from lopping your head off. If you have a basement, that’s ideal, just make sure you’re not under anything heavy upstairs (like an entertainment stand or fridge) in case the tornado actually does hit and the floor above you collapses.

If you’re caught in a vehicle, get to the nearest business and take shelter there. Don’t take shelter in a box store, since those aren’t built to survive strong thunderstorms let alone a tornado. Hiding under a bridge is the best way to die in a tornado—the winds speed up as they press under the bridge, potentially pelting you with debris traveling at lethal speeds, not to mention the potential to suck you out. If you can’t drive away and have nowhere else safe to go, lie flat in a ditch. Even weak tornadoes can destroy vehicles and anyone in them, so you don’t want to be caught in one when a tornado is bearing down on you.

If you’re caught in a heavy thunderstorm while you’re on the road, pull over to a safe location when it’s possible to do so. Parking lots are your best option. Even if there’s no threat of a tornado, never park under a bridge or overpass during a severe thunderstorm—doing so can (and usually does) cause traffic jams, or worse, a pile-up accident.

Keep an eye on warnings issued by your local National Weather Service office—in addition to the countless smartphone apps that beep and ping during an alert, most AM and FM radio stations relay warnings as well, especially for larger population centers. If you’re looking for good radar data, Weather Underground’s website provides excellent radar imagery for you to watch storms as they draw closer to you.

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