It's always bothered me when people say "What global warming? We have snow on the ground in X southern area!" because I know that snow in one area doesn't mean squat.

Today, I learned that snow in southern states is probably caused by global warming.

It's all about the Jet Stream. It takes cold low pressure systems from Alaska east and, if the stream meanders far enough, south as well. With the added energy in the atmosphere from greenhouse gases trapping radiation, the Jet Stream meanders farther south and is more likely to have enough energy to transport the cold air that far south.

So, next time some global-warming doubter cites the snow in Texas, tell them that that snow is a sign of global warming