New Maps Could Predict Where Flooding Will Hit Worst
By Jeff Hampton
The National Hurricane Center will launch storm surge inundation maps for the first time this summer, predicting where and how deep flooding will hit here and elsewhere.
Two years ago the maps were tested on the Outer Banks. Data from hundreds of hurricane forecast scenarios was fed into a supercomputer.
Hurricanes and tropical storms are measured according to wind speed. The new maps turn attention to flooding. Storm surge threats could be worsening as the ocean level rises and more people build on the coast, said Jamie Rhome, storm surge specialist with the National Hurricane Center.
"People have focused on wind," Rhome said. "The world is awakening to storm surge."
In the past 50 years, 2,544 people have died in Atlantic cyclones, according to the Miami-based center. The cause of death was determined in 2,325 of those deaths. Of the known causes, 90 percent were water-related and most were drownings. About half of the fatalities were caused by storm surge.
"Water is killing more people than any other hazard in a hurricane," said Rhome, who travels the world to speak on flooding dangers and how to prepare for them.
Recent storms have inundated Manteo, Buxton, Colington, Kitty Hawk and Rodanthe among other communities. Residents are frequently taken by surprise when the water rises several feet and severely damages property. Soundside flooding is often worse than expected. Ocean overwash has breached N.C. 12 repeatedly, stranding residents on Hatteras Island.
Fortunately, no deaths from hurricane storm surge have been reported in Dare County in recent memory, said Drew Pearson, emergency management director for Dare County.
The maps will be available on the National Hurricane Center website and on social media. The color blue will indicate a prediction of at least 3 feet of water above ground level. The colors will progress from yellow to orange to the worst, red, which will mean a forecast of water rising above 9 feet.
The colors demonstrate the reasonable worst-case scenario, said Rich Bandy, meteorologist in charge at the National Weather Service in Morehead City.
The maps will take into account flooding from ocean storm surge, tidal rivers, sounds and bays nearby. Tides, land elevation, uncertainties in the cyclone track, landfall location, intensity, forward speed and size will be figured in, he said.
The hurricane center will also issue storm surge watches and warnings as part of an experimental program available on the center's website.
Hurricane predictions are complicated, said Bandy, who came with Rhome to Dare County last week for an emergency preparedness event at Nags Head Fire Station 16 and in Buxton.
"Hurricane risk is going to vary a lot," Bandy said. "They're all completely different. We look at each storm independently."
The inundation maps were tested during Hurricane Arthur two years ago and accurately forecast severe flooding in Rodanthe and Manteo, Pearson said.
Pearson said he would use the storm surge forecasts in calling for an evacuation. He could take a printout of the colored maps as he knocks on doors calling for people to leave.
"Six feet of water in your house will do more damage than the wind blowing shingles off your roof," Pearson said. "To me, this is a tool we didn't have before."
(c)2016 The Virginian-Pilot (Norfolk, Va.)