In the early days of July, pieces of weather systems were converging to create a disaster over Texas Hill Country that would transform the Guadalupe River into a monster raging out of its banks in the pre-dawn hours of July 4, claiming the lives of more than 129 people. At least 160 are still missing.

The Texas Hill Country has been notorious for flash floods caused by the Guadalupe River. Here's why the area is called "Flash Flood Alley."