Variations in the Intensity and Spatial Extent of Tropical Cyclone Precipitation

The highest intensities of rainfall occur after the hurricanes have weakened to tropical storms, not when they first make landfall as major hurricanes.

Danielle Touma, lead author and postdoctoral scholar at the university's Bren School of Environmental Science & Management

• Heavy and widespread rainfall during landfalling tropical cyclones can cause severe damage and large financial losses
• Investigates the differences in rainfall along tracks of tropical cyclones of different intensities
• Examines the tracks of Atlantic tropical cyclones that made landfall in the southeastern and eastern United States during the 20th century
• Finds that across all major hurricanes, the largest areas and heaviest intensities of rainfall over land occur after they have weakened to tropical storms
• Finds, in addition, that these major hurricanes that have weakened to tropical storms have heavier rainfall over land during the most recent six decades compared to the first six decades of our study period
• The findings indicate that after landfall occurs, the greatest risks of heavy and widespread rainfall are associated with major hurricanes that have weakened to tropical storms and that these risks may have grown in the past century