Hurricane ratings fail to consider deadly rain

TRENTON, N.C.—When meteorologists downgraded Hurricane Florence from a powerful Category 4 storm to a Category 2 and then a Category 1, Wayne Mills figured he could stick it out.

He regrets it. The Neuse River, normally 150 feet away, lapped near his door in New Bern, North Carolina, on Sunday even as the storm had “weakened” further.

People like Mills can be lulled into thinking a hurricane is less dangerous when the rating of a storm is reduced. But those ratings are based on wind strength, not rainfall or storm surge— and water is responsible for 90 percent of storm deaths .

Several meteorologists and disaster experts said something needs to change with the 47-year-old SaffirSimpson Hurricane Wind Scale to reflect the real risks in hurricanes. They point to Florence, last year’s Hurricane Harvey, 2012’s Sandy and 2008’s Ike as storms where the official Saffir-Simpson category didn’t quite convey the danger because of its emphasis on wind.

“The concept of saying ‘downgraded’ or ‘weakened should be forever banished,” said University of Georgia meteorology professor Marshall Shepherd. “With Florence, I felt it was more dangerous after it was lowered to Category 2.”

Once a storm hits 74 mph (119 kph) it is considered a Category 1 hurricane. It ratchets up until it reaches the top-of-the-scale Category 5 at 157 mph (252 kph). Florence hit as a Category 1 with 90 mph winds—not a particularly blustery hurricane—but so far it has dumped nearly three feet of rain in parts of North Carolina and nearly two feet in sections of South Carolina.

“There’s more to the story than the category,” University of Miami hurricane researcher Brian McNoldy said. “While you may still have a roof on your house because ‘it’s only a Category 1,’ you may also be desperately hoping to get rescued from that same roof because of the flooding.”

Susan Cutter, director of the Hazards and Vulnerability Research Institute at the University of South Carolina, said the hurricane center and National Weather Service “have not done a good job at communicating the risks associated with tropical systems beyond winds.”