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.

Numerous scattered showers and storms will continue in the area through Sunday, with pockets of heavy rain and an increase in the risk for flash flooding.

Texas on Saturday faces an upper-atmosphere wave of low pressure that could trigger storms and an increasingly deep flow of Gulf moisture.

Floodwaters be contaminated with debris as well as high levels of bacteria, chemicals, waste and other pollutants, which can cause prolonged health risks, experts say.

North Texas is currently not under a flood watch, but that could change as storm chances increase this weekend. Scattered thunderstorms are expected Saturday and Sunday, with a Level 2 out of 4 risk for excessive rainfall on both days.

Texas has identified more than $50 billion in flood control needs, but lawmakers have devoted just $1.4 billion to address them

At least 27 campers and counselors at Camp Mystic perished in Friday's floods, with the total death toll in the floods now surpassing 100.

Kerr County failed to secure a warning system, even as local officials remained aware of the risks and as billions of dollars were available for similar projects.

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.