Summit County Citizens Voice

Is Hurricane Katia in the making?

A cluster of thunderstorms about 400 miles south of the Cape Verde Islands is likely to develop into a tropical cyclone in the next two days.

SUMMIT COUNTY — Just as Hurricane Irene was downgraded to a post-tropical system after grazing the East Coast, forecasters say a tropical wave south of the Cape Verde Islands, off Africa’s west coast, has a near 100 percent chance of developing into the next tropical cyclone of the season. If it reaches tropical storm force levels, it would become Katia, the 11th named system of the season.

The early stages of formation suggest a classic Cape Verde-type storm, named for the area where tropical waves of thunderstorms move off the African continent and start to coagulate and swirl counter-clockwise. The so-called Cape Verde hurricanes often are the strongest of the season because when they follow their typically westward track, they move over areas of warm water for a long distance, giving them plenty of time to strengthen.

On average, each hurricane season sees the formation of  two Cape Verde storms, with as many as five in active years. Some years, no tropical cyclones form in that area.

The storms often reach hurricane strength before reaching the Caribbean, but sometimes turn northward into the open waters of the Atlantic before affecting any islands or the mainland of North America. The exact path of the storms depends on the position of a large subtropical ridge of high pressure that dominates the weather over the southern Atlantic in late summer.

The clockwise circulation around the high guides the tropical systems to the west and then gradually to the north, depending on the exact position of the ridge. Meteorologists don’t completely understand what turns a cluster of thunderstorms into a rotating cyclone, but they continue to study the phenomenon in order to develop better lon-range forecasts. Read this NPR story about scientists investigating the Cape Verde formation zone.

Filed under: climate and weather, seasons Tagged: | Atlantic Ocean, Cape Verde, Cape Verde hurricanes, Cape Verde Islands, Hurricane Irene, Hurricane Katia, Tropical cyclone, Tropical wave