Obtaining a Climatology of Extratropical Transition Tornado Events Associated with Atlantic Basin US Landfalling Tropical Cyclones (34)

Alec Mau, Mississippi State University, Starkville, MS

Dr. Andrew Mercer, Mississippi State University

 

Abstract:

Despite well-known risks associated with tornado incidence during a landfalling tropical cyclone, there is no accurate way to forecast which systems are more or less tornado prone. There also is a lack in continuity in overall forecasting because the transition of the tropical cyclone to an extratropical phase often shifts the forecast focus from one NOAA office to another. The purpose of this research is to develop a climatology of tornado incidence, severity, and frequency associated with all landfalling Atlantic Basin tropical cyclones that have undergone an extratropical transition in the United States from 1995 (the beginning of the Doppler radar era) to 2016. Utilizing NCEP reanalysis data since 1995, we tracked and logged landfalling tropical cyclones as they underwent extratropical transition, often logging positions and times of closed cyclones that extended beyond NOAA's HURDAT log, to establish a climatology of U.S.-landfalling tropical cyclones. This established climatology is combined with the tornado report database provided by NOAA's Storm Prediction Center to formulate climatological characteristics of the tornadoes associated with extratropical cyclones that originated as landfalling tropical cyclones. Statistical climatologies of tornado EF ranking, path length, path width, and overall tornado counts by individual events are analyzed post-transition to illustrate the specific risks these isolated tornadoes pose. As threats for tornadoes within landfalling tropical cyclones persist past the transition phase, it is important to understand the inherent risks associated with these tornadoes. This research will provide valuable information regarding the risk of isolated tornado formation within a tropical cyclone as it undergoes extratropical transition.