New Scientist: Tornadoes are aping buses: you wait ages and then a bunch of them come along at once. The twisters are increasingly arriving in clusters, with some days spawning more than 30 across the US, according to an analysis of weather records.
Global warming may be to blame. Climatologists have long suspected that a warmer world would influence tornadoes but the evidence has been scant. In particular, the number of tornadoes has held steady for decades. It's when they do hit that they seem increasingly...