A Climatology of Catastrophic Flooding in Texas from Tropical Cyclones

Hurricane Harvey brought catastrophic flooding to much of southeast Texas and Louisiana. Numerous media reports stated that the flooding was unprecedented. While this is true when considering both the severity and areal extent in a combined sense, there have been numerous instances during the 50 years prior to Harvey where the flooding has been as severe or as widespread in southeast Texas. Since 1967, there have been at least 10 tropical cyclones (TCs) that have produced at least 20 inches of rainfall in Texas. This equates to a return period of a major flood event of slightly more than once every 5 years. TCs have caused more than 40 inches of rainfall 4 times, or about once every 13 years. This shows that major flooding from landfalling TCs in Texas is relatively common. The 16 year gap between major flood events between Allison in 2001 and Harvey is quite unusual. The frequency of TC flooding in Texas causes significant impacts upon the lives of people in southeast Texas, as well as the businesses as the flooding can cause significant destruction to property as well as significant loss of life. This can cause people to be displaced, as well as business operations to be suspended until recovery is complete. Thus, a study that quantitatively documents the frequency and severity of severe to catastrophic Texas TC flooding is warranted.

This study will investigate what makes Texas especially prone to major flooding from landfalling TCs. The study will investigate the synoptic environments that have been present during major TC flood events in Texas to determine if there are any environmental signals that will allow for better forecasting of these events well in advance. Better forecasts will allow for better mitigation of loss of life and potentially property damage. The results from the study will be presented at the conference.