TC-Tornadoes in Florida

As a part of my graduate thesis research, I looked into tornado formation in relation to nearby and landfalling hurricanes in Florida. The thesis, titled Geographic analysis of tornadogenesis from landfalling and nearby tropical cyclones in the state of Florida, was completed and successfully defended in the summer of 2013.

Video of the Thesis Defense from Charles Roop on Vimeo.

ABSTRACT

Tropical cyclone (TC)-spawned tornadoes in Florida were analyzed to determine patterns of occurrence based on storm and geographic features. Tornadoes were determined to be associated with a landfalling or nearby TC if a tornado occurred within 800 km of the TC’s center of circulation. TC-tornadoes were analyzed for patterns based on distance and angle from TC’s center, topographic influences, population biases, and influence based on time of landfall. Most TC-Tornadoes tend to occur more often before landfall than after. It was discovered that tornadoes have occurred in different areas with respect to the bearing from the center depending on the landfall location and time of landfall. It was also discovered that land use type and elevation had little to do with TC- Tornado occurrence. The results do suggest some population bias. The findings will be a guide for operational meteorologists to aid in forecasting likely tornadogenesis from TCs.

KEY FINDINGS

  • TC-tornado development is not likely based on geographic variables such as land use type or elevation.
  • Development was more dependent on path and landfall location.
  • There is some evidence of a population bias on a county level
  • With landfalling TCs in the western part of Florida, tornadoes were more likely in the northeastern quadrant of the storm before landfall. At or after landfall, tornadoes were more likely in the northeastern and eastern side of the tropical system. (See Fig. 8)
  • With landfalling TCs in the eastern part of Florida, the north-northwestern side of the storm had the most tornado development. At or after landfall, it was the east-southeastern side of the storm with the highest mode of tornado development. (see Fig. 8)
  • With landfalling TCs in the western part of Florida, tornado frequency was the highest between 300-399.9 km (~186-249 miles) from the center of circulation before landfall. At and after landfall, it was closer to the center of circulation (This decrease in the distance in part may have to do with the narrow land of the Florida peninsula.) (See Fig. 9)
  • With landfalling TCs in the eastern part of Florida, most tornadoes occurred between 200-299.9 km (~124-186 miles) from the center of the storm before landfall. At or after landfall, the relative distance from the center peaks between 100-300 km (~62-186 miles) and 400-500 km (~249-311 miles). It’s worth noting that the sample size with the eastern TCs is low.