WATCH: How heavy rain caused catastrophic flooding in Texas

ABC News Chief Meteorologist Ginger Zee shares how the fast flood threat developed so quickly and how early people were warned about the dangers.

​ABC News Chief Meteorologist Ginger Zee shares how the fast flood threat developed so quickly and how early people were warned about the dangers.   ABC News Chief Meteorologist Ginger Zee shares how the fast flood threat developed so quickly and how early people were warned about the dangers.