85 Percent of US Hurricanes Come From... Africa

The United States - especially the East Coast - has experienced some major hurricanes in the past, including Hurricanes Katrina, Sandy and Irene. Now new research shows that 85 percent of these tropical cyclones come from Africa, of all places.

Hurricanes form from three main ingredients: moisture, warm ocean temperatures, and the rotation of Earth. But what causes a hurricane to go from a few storm cells and atmospheric disturbances to a full blown storm? According to new findings published in the journal Geophysical Research Letters, intense thunderstorms in Western Africa are actually in part to blame.

"85 percent of the most intense hurricanes affecting the US and Canada start off as disturbances in the atmosphere over Western Africa," researcher Colin Price from Tel Aviv University said in a statement. "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."

Focusing on hurricane season (June through November), Price and his team analyzed images taken by geostationary satellites, which orbit Earth at the precise speed of Earth's rotation and take pictures of cloud cover every 15 minutes. Cloud cover is a good indicator if a hurricane is going to occur - the more clouds in an area, the larger the atmospheric disturbance.

They then compared this cloud data with hurricane statistics, including intensity, date of generation, location and maximum winds.

The results show 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.

"We wanted to know what was so special about these 10 percent of disturbances that develop into hurricanes," Price said. "By looking at each of these storms individually, we found again that the larger the cloud coverage originally in West Africa, the higher the value of the accumulated cyclone energy in a future hurricane. The conclusion, then, is that the spatial coverage of thunderstorms in West Africa can foretell the intensity of a hurricane a week later."

Researchers hope that this information can help US weather forecasters better predict when and where a potentially destructive hurricane is going to occur. All they have to do, it seems, is look to Africa.

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