The risk of the catastrophic flooding that struck Texas Hill Country as people slept on July 4 and left at least 120 dead was potentially underestimated by federal authorities, according to an ABC News analysis of Federal Emergency Management Agency data, satellite imagery and risk modeling.

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.

Some regions in the mid-Atlantic are also facing risks of flooding. On Sunday, Tropical Storm Chantal flooded parts of North Carolina, where more than 10 inches of rain fell near the Chapel Hill area. The Haw River, near Bynum, North Carolina, crested to nearly 22 feet, the highest crest on record there, as a result of those heavy rains.

Dick Eastland, the Camp Mystic owner who pushed for flood alerts on the Guadalupe River, was killed in last week’s deadly surge.

As a climate scientist who calls Texas home, I can tell you that the Hill Country of Texas is no stranger to flooding. Meteorologists often refer to it as “Flash Flood Alley” because of its steep terrain, shallow soils, and its history of sudden and intense rainfall.

President Donald Trump will head to Texas for a firsthand look at the devastation caused by catastrophic flooding that has killed at least 120 people, which the administration has characterized as a o

At least 120 people are dead from the devastating flooding in the Texas Hill Country.

More than 160 people still are believed to be missing and at least 115 have died in the floods that laid waste to the Hill Country region of Texas. The large number of missing sug