Forecasting tropical cyclone tornadoes and impacts: Report from IWTC-X

This report synthesizes global tropical cyclone (TC) tornado research and operational practices to date. Tornadoes are one of the secondary (and lesser researched) hazards contributing to the devastation TCs leave in their wake. While gale-force winds and storm surge produce the majority of damage and fatalities globally, TC tornadoes also pose a fatal threat, complicating evacuation plans and protective actions as the storm moves inland. Climatological studies characterize TC-spawned tornadoes as usually weak and short-lived, primarily originating from miniature supercells in the outer rainbands. These tornadic features pose challenges to forecasting and radar detection. Additionally, TC tornadoes can pose a threat to communities 12 h prior to and beyond 48 h after a TC makes landfall.

Research, both basic and operational, has increased globally over the last few years in efforts to move from a climatological to ingredients-based approach to detect and forecast TC tornadoes. While the United States has led the charge, given the increased exposure to tornadoes year round, other nations such as China, Japan, and Australia have increased their efforts to record and detect TC tornadoes. Despite these advancements, more work needs to be done globally to understand the TC environment conducive for tornadic activity. Recommendations for future forecasting and research for TC tornadoes include i) develop a comprehensive global tornado database to improve research and forecasting efforts; ii) apply innovative technology to detect tornadoes; and iii) conduct field campaigns to thoroughly sample TC tornado environments, particularly along coastlines.