Hurricane Harvey went from weak to dangerous in 56 hours

HOUSTON -- Harvey went from not even a tropical storm to a major Category 4 hurricane in 56 hours, an incredibly fast intensification for a storm.

On Wednesday at 10 am CDT, the National Hurricane Center said Harvey — which had been a tropical storm that faded away on Aug. 19 — had reformed as a tropical depression, a step below a named storm. Harvey's maximum winds were 35 mph.

And by 6 p.m. CDT Friday, Harvey was a Category 4 hurricane with 130 mph winds and knocking on the Texas coast as what will likely be the strongest hurricane to hit the US in about 13 years.