An Examination of Freshwater Flooding in Texas from Tropical Cyclone Landfalls

Tropical Cyclones have a long history of causing significant freshwater flooding from rainfall across the western Gulf of Mexico coast. One of the most famous instances of this was in June 2001, when Tropical Storm Allison caused more than 40 inches of rain to fall in the Houston area, leading to catastrophic flooding. However, Ortt and Self (2018) showed that Allison was actually only the fourth wettest tropical cyclone (TC) rainfall event in Texas since 1978, as Amelia, Claudette, and Harvey all produced higher rainfall totals. In addition, this study showed that four of the top five and 6 of the top 10 wettest TCs that affected the continental United States occurred in Texas.

A detailed examination of this data shows that Texas has a unique vulnerability to extreme rainfall events from landfalling TCs, and in their 2018 study Ortt and Self showed that there may be a signal in the monthly mean 200-850 hPa wind data that could be used to predict when there is a risk of an elevated flood risk in Texas due to a landfalling TC. This presentation will update and expand on these findings, by further evaluating the steering patterns associated with TCs that cause extreme rain events, using not only monthly mean data, but also daily data to better evaluate the in situ environment that affected the motion of the TCs during the times when there was an extreme TC rainfall event.