In Case You Weren’t Aware…
...yet another version of the "snowpocalypse" is coming. Very potent winter weather will be affecting a large swath of the country, and some very important hubs, like Dallas-Ft. Worth and Chicago O'Hare (and Midway) will be affected. And that same storm will eventually make its way to the East Coast, affecting Washington, New York, and Boston. It's gonna be rough.
Basically, many, many people will have trouble getting around. One report from earlier in the day said that over 3,000 flights have been pre-emptively cancelled.
As per usual, many airlines have launched their usual travel policies for storms like this - basically, if you're on a nonrefundable ticket you can make change without having to pay a fee. USA Today's Today in the Sky blog has a handy list of these policies.
But, considering the huge impacts on this storm - finding new flights based on your schedule might be tough.

