For years, I had wanted to observe one of the small, often beautiful tornadoes that develop from shallow, fast-moving supercells that develop in arcs of convection, just ahead of a compact middle-upper level low. Colloquially, they're called "cold-core" tornadoes, after the swath of cold air aloft that accompanies such cyclones, and that contributes to the instability supporting the supercells. This day afforded just such an opportunity. After several non-tornadic supercells and funnels seen farther W in the arc, in North Dakota, this ghostly tornado finally appeared just E of the Minnesota border. The small, ragged updraft area didn't look like much, but it spun up fast as it moved away from us. Not long afterward, we while cruising up US-75 (known as Central Expressway in Dallas), we saw a road sign: "Canada 90." We knew we had traveled a long way from home. It was two firsts for me: "cold-core" and Minnesota tornado.
3 SSE Fisher MN (17 Jun 10), looking NNE