largeThis afternoon, it was thunder snowing in San Francisco, blizzarding in the Dakotas, and gusting furiously off the coast of New England. For this audacious weather, you can thank a trio of major storm systems aligned with military precision over North America. This triple threat – which the National Weather Service calls “highly unusual” – illustrates the kind of violent systems that herald the arrival of spring, the beginning of the so-called tornado season. And right on schedule, today there was indeed a confirmed spotting of a hail-encircled tornado thrashing through west-central Minnesota. At last check there were no reports of major damage or injuries, lucky for all. You can get a space-alien-eye’s view of this procession of cyclones thanks the above composite satellite imagery, put out by the Space Science and Engineering Center at the University of Wisconsin-Madison. (A high-res version is here.) It was tweeted out by Darren Maier, a meteorologist in Eau Claire, Wisconsin, who writes: “west coast, central, east coast.. 3 well developed cyclones encompassing the US this pm!” More