A week ago, (October 25 - 27, 2010) this system developed over the Great Lakes lowlands and the Midwest. I've been seeing large events like this develop periodically, especially in the months where we change from fall into winter, or winter into spring.
Look as the size of this thing! And the speed! And apparently the air pressure dropped REALLY low under the centre of the event - like happens in a Category 3 hurricane!
The climatologists at NASA call this a "Strong Extratropical Cyclone". The name they use seems to indicate it's pretty unusual.
As I say here at FilterBlogs; Climate change = Various Weather. How's this for "Various"?