Tuesday, May 03, 2011

Second twistiest

kw: weather phenomena, tornadoes, records

As my wife and I drove across Ohio and Indiana last Tuesday, 4/26/2011, we were listening to Kentucky radio stations and their almost continuous tornado warnings or reports. The following day, the 27th, we were able to hear a few more such reports, but went out of range before we got to Missouri. We were glad to be north of all the bad weather, but sorry for the people caught up in it, and we prayed for them. In more than 300 cases, the answer to such prayer was "No." That day marked the middle of a cluster of tornado outbreaks that may yet rival the Super Outbreak of 3/19/1974, the worst outbreak of the Twentieth Century. I have a few notes on that outbreak in a book review I wrote in 2007.

We did not know at the time the magnitude of the event. It may yet exceed some or all of the records set in 1974. The only record that is sure to stand is the 1925 record of nearly 700 killed by a single tornado, which also had a ground damage track nearly 220 miles (350 km) long. To compare:
  1. Tornadoes – 1974: 148 in 18 hours. 2011: 211 in 48 hours, but it is not known if more than 148 occurred in any single 24-hour period.
  2. Deaths – 1974: 300-330. 2011: 334 and counting, making it the second deadliest outbreak after the 1925 event.
  3. Ground track – 1925: 219 mi (352 km). 2011 (Tuscaloosa-Birmingham tornado): 80 miles, in a supercell that produced tornadoes over a 380-mile (610 km) path, but no single track that exceeded the T-B tornado.
The Tuscaloosa-Birmingham tornado may also be the second widest recorded. Its damage track is 1.5 miles (2.4 km) at its widest, while the huge Wilber-Hallam tornado of May 22, 2004 was 2.5 miles (4 km) at its widest. Such tornadoes are almost as wide as they are tall; their tops are typically at an altitude of 3-4 miles (5-6.5 km) above the ground surface. The dynamics of such storms begin to approach those of hurricanes, which are considerably wider than they are tall.

There are the inevitable questions about global warming. One set of events does not necessarily signal a trend, but it is true that a warmer climate will have more energy available for producing extreme weather. The climate certainly is warming up, and human additions to the greenhouse gas budget are now known to be a factor. There is a price to pay for revving up Mother Nature!

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