Predicting which African storms will intensify into hurricanes

A press release from the American Friends of Tel Aviv University: Hurricanes require moisture, the rotation of the earth, and warm ocean temperatures to grow from a mere atmospheric disturbance into a tropical storm. But where do these storm cells originate, and exactly what makes an atmospheric disturbance amp up full throttle?

A new study published in Geophysical Research Letters by Tel Aviv University's Prof. Colin Price and his graduate student Naama Reicher of the Department of Geosciences at TAU's Faculty of Exact Sciences finds most hurricanes over the Atlantic that eventually make landfall in North America actually start as intense thunderstorms in Western Africa.

"85 percent of the most intense hurricanes affecting the U.S. and Canada start off as disturbances in the atmosphere over Western Africa," says Prof. Price. "We found that the larger the area covered by the disturbances, the higher the chance they would develop into hurricanes only one to two weeks later."

Using data covering 2005-2010, Prof. Price analyzed images of cloud cover taken by geostationary satellites, which orbit the Earth at the precise speed of the earth's rotation and take pictures of cloud cover every 15 minutes. This enab
led Prof. Price to track the variability in cloud cover blocking the earth's surface in West Africa between the months of June and November — hurricane season.

...According to Prof. Price, only 10 percent of the 60 disturbances originating in Africa every year turn into hurricanes. And while there are around 90 hurricanes globally every year, only 10 develop in the Atlantic Ocean.

..."If we can predict a hurricane one or two weeks in advance — the entire lifespan of a hurricane — imagine how much better prepared cities and towns can be to meet these phenomena head on," Prof. Price says. He is currently examining the thunderstorm clusters around the eyes of hurricanes to study the intensification process of those destructive phenomena....

Hurricane Fred in 2009, with Africa in the background. Via NASA