About 20 million people are currently under a blizzard warning, and double that under a winter weather advisory, for a storm moving into the Northeast today and tomorrow, with snow falling though Wednesday. Thousands of flights have been cancelled. Wind will be at tropical storm force, and occasionally, hurricane force, and coastal flooding is expected to be epic. The total amounts of snowfall will be over a foot for a very large area, and well over that here and there, though this is very difficult to predict.

This is a strong low pressure system that will gather significant energy from a warm sea surface as it moves into the Atlantic.

This is a system that would normally not produce a lot of snow, but the odd configuration of the jet stream (once again) is moving the low pressure system through a pattern that will create an epic blizzard.

Read more here: http://scienceblogs.com/gregladen/2015/01/26/the-great-blizzard-of-2015-fair-to-say-it-is-agw-enhanced/