May 23 - July 29
Investigating Variability in the Number of Tornadoes Among Landfalling Hurricanes
James DiGilio (Northern Illinois University) and Dr. Ben Schenkel (OU/CIWRO & NOAA/NSSL)
What is already known:
- There is a large variability in the number of tornadoes among landfalling TCs.
- TC tornadoes spawn more frequently near the coast.
- Weak-to-moderate damage ratings are usually assigned to TC tornadoes.
What this study adds:
- Low numbers of TC tornadoes occur near the coastline, whereas high numbers of tornadoes occur further inland.
- More damaging tornadoes (EF-2+) are more likely to form when a TC produces high numbers of tornadoes.
- High numbers of tornadoes are characterized by stronger diurnal variability than low numbers of tornadoes.
Abstract:
There is large variability in the number of tornadoes spawned by landfalling tropical cyclones (TCs). However, our understanding of why this variability exists remains incomplete. Hence, this study statistically analyzes differences in the characteristics of episodes of low and high numbers of tornadoes in landfalling TCs using multidecadal tornado and TC track data. These results show that low numbers of tornadoes tend to spawn near the coastline, whereas high numbers of tornadoes occur further inland. Similar, episodes with low numbers of tornadoes are associated with TCs near the coastline, whereas episodes of high numbers of tornadoes are associated with a TCs typically further inland in the Deep South. Tornadoes also spawn closer to the TC center with the downshear left quadrant during episodes of low numbers of tornadoes, whereas high numbers of tornadoes typically occur at outer radii in the downshear right quadrant. Episodes of high numbers of tornadoes are also characterized by stronger diurnal variability than low numbers of tornadoes. Finally, more damaging tornadoes are favored during episodes of high numbers of tornadoes. Together, these results provide the foundation for the improvement of tornado forecasts in landfalling TCs.