Tropical cyclone season is underway. The term includes tropical storms, with wind speeds up to 74 mph, and hurricanes if wind speeds increase beyond that mark. The names Arthur, Bertha and Cristobal have already been used up. Bertha brought back memories of her 1996 namesake. Nicknamed “Big Bertha” as the 1996 storm approached Wilmington, North Carolina, it weakened considerably upon making landfall near Wrightsville Beach. Still, Bertha’s 90 mph winds were sufficient to choke Wilmington (population 61,000 in 1996) with fallen trees and branches. This year’s Bertha didn’t grow beyond tropical storm status, although the Charleston, South Carolina area received torrential rains.
After Cristobal’s landfall in the Gulf of Mexico, the next storms on the 2020 list will be Dolly, Edouard, Fay, Gonzalo, Hanna, Isaias, Josephine, Kyle and Laura. In an average year, the list would stop with these 12 names. However, the National Oceanic and Atmospheric Administration now predicts a busier-than-average hurricane season, expecting 13 to 16 named storms. This could bring Marco, Nana, Omar and Paulette to Atlantic and Gulf shores, mainly due to warmer than normal ocean water. Tropical cyclones depend on this. When water vapor condenses in the clouds, it releases energy into the storm.
A busy hurricane season doesn’t automatically mean doom for all coastal cities. Unlike frontal systems, of which we had a few rushing into Georgia at freeway speeds this past spring, the tropical systems move slowly. While they are on the ocean, they advance at the speed of a swift sailboat, which is between 8 and 12 mph. They also bumble around, changing direction frequently. This controls the critical issue of where, and how, they hit land. Say, for example, you have a home in St. Mary’s, near the Florida border, and Josephine is about to make landfall just north of there. Because tropical cyclones rotate counterclockwise, St. Mary’s may receive only northwesterly wind flow, coming from the land, with limited flood potential. But Savannah, 100 miles to the north, could experience southeasterly winds, bringing tall ocean waves and severe flooding. In spite of all the data analysis and attempts at forecasting, no one can say where exactly the coming storms are going to hit. All coastal communities are at greater risk than our homes in North Georgia. But no one can predict which part of the coast may suffer this year.
Rudi Kiefer, Ph.D., is a professor at Brenau University, teaching physical and health sciences on Brenau’s Georgia campuses and in China. His column appears Sundays and at gainesvilletimes.com.