In 1973, the National Hurricane Center introduced the Saffir-Simpson scale, a five-category rating system that classified hurricanes by wind intensity.
With catastrophic hurricanes regularly blowing past the 157-mph threshold, some scientists argue, the 1970s-era Saffir-Simpson five-category scale no longer adequately conveys the threat.
When Dr. Robert Simpson boarded a military helicopter from Miami on Aug. 19, 1969, bound for the central Gulf Coast, little could prepare him for the horrors he would witness as the first National Hurricane Center director to survey the immediate aftermath of a hurricane.