Darn.  

We didn't take the news casts seriously enough.

We all died.

We didn't uncover vent pipes, forgot to put warm clothes on, died of heart attacks shoveling snow, starved to death because we forgot to buy enough food to last 2 days, we went outside without shoes on and caught pneumonia, blew out the pilot lights on our stoves, let our pipes freeze and drown when they burst, drove our cars off the roads and got buried by snowplows, didn't shut our windows and we froze in our beds.

And those few of us left alive have commit suicide because everyone else is dead.