I heard an item on the radio where the twin twisters that clobbered a Nebraska community were said to be described by meteorologists as rare; the question "Is this due to climate change?" was also posed and left dangling. Investigating further at Google News, I found another item where a storm chaser was saying "I've never seen anything like this".
I then found an article by Andrew Freedman which says there's a wide range of tornado types and that storms which split aren't all that rare.
Pioneering tornado scientist Theodore Fujita, who devised the Fujita Tornado Damage Scale that is still used to classify tornado intensity, identified many types of tornadoes, some of which bore similarities to the twin twisters in Nebraska on Monday.
For example, the Palm Sunday tornado outbreak of 1965, during which nearly 50 tornadoes touched down and 271 people died, there was a well-documented dual tornado that struck close to Toledo, Ohio. A study Fujita published with his colleagues found that this tornado split for only a short time, coalescing back into a larger funnel soon after a famous picture was taken that bears some resemblance to the Pilger tornado.
"A single funnel split into two and then reorganized into one after about a minute," the study says.
Interesting reading.
(Score: 2) by Blackmoore on Thursday June 19 2014, @04:51PM
Tornados are a jaw dropping sight where they are uncommon (say the Rust belt USA) even little waterspouts on lake Erie are impressive but to see one in person will let you realize how much power they contain.