A systematic way of tornado outbreak classification.

Research into the climatology of tornado outbreaks can serve as a basis for better forecasting of these events, especially in areas that are prone to severe weather. However, to provide such basis, it is crucial to characterize and classify tornado outbreaks, as there is no one unambiguous definition of a “tornado outbreak” in the scientific literature [1]. The method presented in this research offers a systematic way to group days with multiple tornadoes into outbreak days or non-outbreak days. To determine days with tornado outbreaks, we analyzed the severe weather database with all tornado reports recorded from 1950 to 2017 form the Storm Prediction Center of the U.S. National Weather Service. The technique adopted in this research is based on the methodology of Shafer and Doswell, 2011 [2] and uses kernel density estimation (KDE) on tornadoes greater or equal to F2 rating that occurred in the contiguous part of the United States. The KDE approach enabled us to identify clusters of tornado reports associated with a single outbreak event and then outline their associated geographic regions. This method can serve as a starting point for any project that studies tornado outbreaks.

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1) Mercer, A.E., Shafer, C.M., Doswell III, C.A., Leslie, L.M. and Richman, M.B., 2012. Synoptic composites of tornadic and nontornadic outbreaks. Monthly Weather Review, 140(8), pp.2590-2608.

2) Shafer, C.M. and Doswell, C.A., 2011. Using kernel density estimation to identify, rank, and classify severe weather outbreak events. Electronic Journal of Severe Storms Meteorology, 6(2), pp.1-28.