Garrett’s Blog: Tornado Drought

ef1plus12

If you thought this year’s tornado season was low on tornado numbers; you’d be right. In fact, The 12-month period starting at May of 2012 to April of 2013 recorded the lowest number of tornadoes since tornado record keeping started. Data has been kept regularly since around 1954. So far during this 12-month consecutive timespan only 197 are estimated to have occurred.

NSSL Researcher Harold Brooks, Ph.D., showed the last time the (12-month) count was this low was in the year 1991 with 247 tornadoes ranked EF1 or larger. In 2011, there were 1,691 tornadoes.

Perhaps that’s what’s most intriguing about the low tornado number; the spring of 2011 was unusually violent and broke numerous records relating to high numbers of tornadoes: most tornado deaths in this century, highest number of tornadoes, and more violent tornadoes recorded (EF4 or EF5). 2011 was the year the year E5 tornadoes hit Oklahoma City, Joplin, Mississippi, & Alabama; and also produced violent tornadoes in St. Louis and Denning, AR.

The extended forecast for our area does not favor widespread severe weather. A large blocking pattern will continue to affect our weather. Additionally, the jet stream is unorganized and in a split-flow pattern which is not favorable for widespread severe storms. Long range forecast data is available for about 10-12 days as accuracy diminishes with increasing time showing little to no wholesale weather changes in the pattern through the next 2 weeks.

Garrett

Link to Harold Brooks blog: http://www.norman.noaa.gov/2013/05/low-tornado-numbers-and-low-tornado-deaths-may-2012-april-2013/