Tornado Alley May Be On The Move: Where it is Going and What You Need to Know (Credit: Nature Journal)
Recent tornado outbreaks in the Southeast U.S. have spawned talk of extreme severe weather that is occuring in an area of the country that is not typically used to such extreme tornado outbreaks. An early March outbreak in eastern Alabama ended with 23 fatalities and over 90 people injured after an EF4 tornado tore through over 60 miles of the state. By mid-March, another outbreak yielded 15 tornadoes in the same state, albeit no fatalities or injuries occurred during this outbreak.
The outbreaks may come as a precursor for what the 2019 Tornado season, which usually is beginning in February and March, could bring to the Central and Southeast U.S. Several factors go into creating a record-breaking tornado season: above-average temperatures, increased moisture from the Gulf of Mexico, and even the development of El Nio. However, it isn’t the frequency or magnitude of tornadoes that is catching most scientists’ intentions (although these are important nuances that should be noted). It is the movement of tornado outbreaks that has alerted scientists and prompted new tornado research. In 2018, two researchers, Vittorio A. Gensini of Northern Illinois University, and Harold E. Brooks of the National Severe Storm Laboratory in Oklahoma, studied the spatial trends of tornado outbreaks.
The results were clear. Tornado outbreaks are on the rise in the Southeast U.S. in states like Arkansas, Mississippi, Alabama and Kentucky. This is in comparison with the Great Plains, historically known as “Tornado Alley”, where tornado outbreaks are actually decreasing. The study used STP, the Significant Tornado Parameter index, and U.S. climatological tornado data to analyze where tornadoes are occurring and in what severity. The STP measures the magnitude of a tornado of EF2 strength or greater, and how likely strong tornadoes will occur in a given area. The scientists in this study were able to use STP to explain the changes in regional tornado formation in recent decades.
You may be wondering why this is a big deal. Brooks and Gensini noted increased physical risk and social vulnerability for people in the Mid-South as compared to the Central U.S. While most of the country’s tornadoes occur in the Plains, most tornado casualties occur in the Southeast. This may have to do with a lack of proper tornado-resistant infrastructure. In the Plains, most infrastructure dating back decades have been equipped with cellars in the case of a tornadic supercell. In the Southeast, many more people are impoverished, living in structures such as mobile homes and trailers which are not equipped with proper tornado shelters. This could spell disaster for an area with an increasing frequency of tornadoes, and it may only get worse.
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© 2019 Weather Forecaster Jacob Dolinger