Over just two hours, the Guadalupe River at Comfort, Texas, rose from hip-height to three stories tall, sending water weighing as much as the Empire State building downstream roughly every minute it remained at its crest. The force of floodwater is often more powerful and surprising than people imagine.

Key questions remain unanswered about the actions Texas officials took both before and during the catastrophic July Fourth holiday floods remain unanswered

The president has defended his administration's response to the fatal flooding amid criticism that federal assistance could've been provided more quickly.

Well, it could take months for Texas families to experience some form of closure as more than 170 people remain missing, nearly a week after those deadly floodwaters rushed in the Texas Hill Country on July 4 as four months of rain fell in just two days over central Texas.

In what experts call "Flash Flood Alley," the terrain reacts quickly to rainfall steep slopes, rocky ground, and narrow riverbeds leave little time for warning.