NWC REU 2019
May 21 - July 30



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Assessing the Role of Tropical Cyclone Size in Tornado Production

Marco Paredes and Ben Schenkel


What is already known:

  • There is large variability in the number of tornadoes produced by tropical cyclones.
  • Tropical Cyclones exhibit a large variability in their outer size.
  • Previous work has shown that tropical cyclones with larger outer size produce more tornadoes, but used a size metric that was highly subjective and highly influenced by environmental changes.

What this study adds:

  • Use of an updated outer size dataset to revisit prior work examined the relationship between tropical cyclone outer size and tornado production.
  • In contrast with prior work tropical cyclone outer size is not a dominant factor influencing the radius of tornado occurrences.
  • In contrast with prior work, tropical cyclone size is not a dominant factor influencing the number if tornadoes produced.


Tornadoes in tropical cyclones have large amounts of variability in their behavior from year to year and even through the lifetime of a single storm. While these tornadoes are weaker on average than those occurring in midlatitudes, they still pose a hazard that can bring potential harm. Previous studies have attempted to establish the relationship between tropical cyclone size and tornado production and behavior and concluded larger tropical cyclones will produce more tornadoes at a further distance from the storm center. However, these previous studies used an antiquated, highly subjective dataset and outer size metric to establish this relationship. Revisiting prior work, uses a less subjective, more reliable outer size metric from a modern outer size dataset to conduct a statistical analysis to determine the validity of the relationship. Our analysis show that tropical cyclone size was determined to not be a strong factor in determining either tornado radius or number. While outer size may not provide a direct influence on tornado behavior, a more extensive look at convective evolution in tropical cyclones would greatly benefit the field in future work.

Full Paper [PDF]