"Major snowstorms are set to bury the mid-Atlantic states this weekend after record snowfalls in December. Last month California was awash in rain. The Gulf states have seen heavy weather lately as well.

Turns out it's not just a run of bad luck. What's behind a lot of this winter's weather is El Nino, the tropical weather pattern that starts in the Pacific.

Scientists knew last summer that this was going to be an El Nino year. But it wasn't until the winter that its effects really hit the United States. "

Christopher Joyce reports for All Things Considered February 4, 2010. [2]