How To See the Northern Lights
According to current projections from the SWPC, the G2 warning is in effect until 11pm EST. That alert means the aurora could be seen through parts of 19 states. Then a G1 warning remains in effect until 2am EST, which can still be seen in parts of the U.S. (As far south as the green line in the above map.)
However, seeing the display isn't just as easy as walking outside and looking up. (At least, it's not for most people.) You'll need to get far from the light pollution of urban centers. If you're in an urban area, you probably won't be able to see anything. An SWPC representative previously told Thrillist, "You need very clear skies, a good view of the northern horizon (no trees, buildings or hills), and it needs to be dark."
The view of the northern horizon is important because, at least in the U.S., the display will be to the north and not directly overhead as you might find in places like Finland or Alaska.
Yes, these kinds of warnings pop up from time to time, but it's not all too common to see the northern lights in the contiguous U.S. Not only do you need a situation like this, but you'll need the weather to cooperate. Additionally, the solar cycle isn't far from its minimum, making opportunities like this less frequent. If you're lucky enough to be in the right place at the right time tonight, it's an excellent opportunity to check the northern lights off your bucket list.