If it seems like it's been a particularly warm winter, you're right -- it has. So far, the Twin Cities hasn't recorded a single day below zero all winter long. University of Minnesota meteorologist Mark Seeley says it's been nearly half a century since truly frigid days were so hard to come by in the first half of winter in the Twin Cities. In the winter of 1954-55, the Twin Cities didn't record their first subzero day until Jan. 15. And the area hasn't had a single