Super Outbreak Dethroned?

Some more notes from the lineup at the National Storm Chasers Convention in Denver. On Saturday afternoon, Greg Forbes, the Severe Weather Expert at The Weather Channel gave an interesting review of the weather events of 2004. Forbes wasn’t sure what to call the year. The Year of the Tornado, since a new record number of twisters (1,750) occurred? The Year of the Tropical Storm Tornado, since landfalling tropical cyclones produced over 300 tornadoes? The Year of the Warm Front Tornado, since many tornadoes occurred along warm fronts? Or the year of the Extended Tornado Outbreak, since outbreaks of tornadoes occurred on every day from May 22nd until the end of the month?

Most interestingly, he proposed that the long reign of the 1974 Superoutbreak of tornadoes was dethroned by the May 29-31 outbreak of last year. Outbreaks are considered to be continuous if there is no break greater than six hours without a tornado. On May 29-31, 2004, 161 tornadoes occurred in 35.2 hours over fifteen states. On the 29th, the outbreak exploded across Nebraska, Kansas and Oklahoma into Missouri. It moved into the Corn Belt on Sunday the 30th and lasted into the wee hours of Monday morning. The 161 tornadoes are more than the 147 recorded in the U.S. during the Jumbo Day outbreak on April 3-4, 1974. Of course, the Superoutbreak tornadoes occurred in just twenty four hours, and had a much greater impact in terms of deaths and damage.

In fact, on Forbes’ own impact scale, the April 3-4, 1974 outbreak easily ranks as number one. He bases that scale on the number of tornadoes, number of killer tornadoes, number of F4 and greater tornadoes, number of F2 and stronger tornadoes, damage, number of tornadoes per hour, number >400 yards wide, total path length and number of states affected.

More next week. Plus some controversial thoughts on tornado formation.