Wind speed alone doesn’t predict hurricanes’ power * By AMY WOLD
* Advocate staff writer
* Published: Feb 28, 2009 - Page: 10A - UPDATED: 12:05 a.m.
LAFAYETTE — The potential damage and danger of a hurricane can’t be defined by a single number as is sometimes done with the Saffir-Simpson category scale, warns The Weather Channel’s tropical program manager Steve Lyons.
“Not all hurricanes of the same category are the same,” he said Friday during a U.S. Department of Commerce 2009 Gulf Coast Marine Conference in Lafayette.
The Saffir-Simpson scale for measuring hurricanes — by which a storm is labeled as Category 1-5 — only measures wind speed, he said. That can be very misleading to the public since wind speed is only one part of the equation when it comes to how destructive a hurricane can be, he said.
For example, Hurricane Charley was a Category 4 hurricane, but it only produced a 6- to 9-foot storm surge while Hurricane Katrina as a Category 3 produced more than 27 feet of storm surge in some locations, he said.
Storm surge — or the water pushed ahead of a tropical cyclone that can cause coastal flooding — can’t be directly tied to a Saffir-Simpson scale number, he said.
In addition, storm surge is something that can have a large impact on a coastal area before the storm is even on the horizon, as was seen during Hurricane Ike in Texas, he said.
“The wind can still be offshore when the water is already coming up,” he said.
Some people on Bolivar Peninsula in Texas had to be rescued before Hurricane Ike made landfall when the storm surge cut off the escape routes before the storm had even arrived, he explained.
The Saffir-Simpson scale, on its own, is not a bad thing, he said. However, too often it’s used to help communicate risk to communities facing a tropical storm or hurricane, and it just doesn’t work, he said.
“We hear a lot of people say, ‘We didn’t think it would be that bad. It was only a Category 2,’ ” Lyons said. “(Hurricane) Ike was Category 2, but it was the strongest of Category 2.”
In addition to wind speeds, hurricane damage potential also depends on the size of the hurricane, how fast it is moving, the amount of rain it drops in an area, the geography of where it hits and how many tornados it spawns, he said.
“Every hurricane leaves its own mark on the coastline, and it’s never the same,” Lyons said.
Rainfall can also be a destructive force during hurricanes, and forecasting how much and where that will fall is difficult and depends on a number of factors including the speed of the storm.
“If it slows down anywhere along the track, that’s where you’ll see flooding issues,” Lyons said.
All of this was evident through last year’s very busy hurricane season, said Jack Beven, senior hurricane specialist from the National Hurricane Center.
Starting with Arthur in early June and ending with Hurricane Paloma in early November, there were 16 named storms in 2008. Of those, Hurricane Gustav became the strongest storm to hit the Baton Rouge area for decades and produced 40 tornados — most of which hit in Mississippi, he said.
Hurricane Gustav was followed by Hurricane Ike, which became the fourth costliest hurricane to make landfall in the U.S., he said.
