The United States Army Corps of Engineers generally calls it the equivalent of a fast-moving Category 3.
[1] The standard project hurricane became "enshrined within the corps," according to an investigation of the levee failures in New Orleans following Hurricane Katrina, who noted that "the corps saw little need to go back and reanalyze "the true risks of catastrophic flooding" in New Orleans.
Even when the National Oceanic and Atmospheric Administration, the successor agency to the Weather Bureau, recommended increasing the strength of the model, the corps did not change its construction plans.
"[1] Dr. David Daniel, the chairman of a panel reviewing the corps' investigation, said in an interview, "It was not a terribly sophisticated or detailed analysis by today's standards.
Also, the calculations of the cost-benefit ratio did not take into account the costs of failure, both economic and social, far greater in an urban area like New Orleans than a rural one.