Extreme Rains in South Texas Associated with Tropical Storm Charley (1998)

In late August 1998 Tropical Storm Charley made landfall along the middle Texas coast spreading extreme rains across portions of South Texas and adjacent northeast Mexico. Over 15 people died during the floods. After traveling more than 200 km inland, the tropical cyclone slowed and stalled over South Central Texas and northeast Mexico.

Rainfall patterns exhibited a diurnal transition from daytime scattered showers around the peripheral areas of the cyclone circulation to nighttime thunderstorms concentrated near the center (core) of the cyclone circulation. The nighttime core rains were associated with the most devastating flooding and deaths. The first night's core rains measured between 150 mm and 200 mm, causing flash flooding and four deaths. The second night's core rains were the most devastating. In Del Rio, Texas, over 250 mm of rain fell during a three-hour period, and over 450 mm of rain fell in less than 24 hours. Over ten people drowned in the overnight flash floods.

Rainfall patterns are explained during the three-day event. Specifically, the transition from peripheral showers to concentrated core rains is discussed. Short-term timing of the heaviest rains, illustrated by satellite and radar images, is explained. The most extreme, concentrated rainfall during the most devastating flash flooding is discussed in greatest detail.