Scientists Tackle Which African Storms Intensity into Hurricanes

Which storms will intensify into hurricanes and which will peter out over time? That's the question that scientists are now tackling. They've taken a closer look at hurricanes in order to find out where they originate in order to make better predictions.

"85 percent of the most intense hurricanes affecting the U.S. and Canada start off as disturbances int eh atmosphere over Western Africa," said Colin Price, one of the researchers, in a news release. "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."

In order to learn more about these hurricanes, the scientists examined data covering 2005 to 2010. They analyzed images of cloud cover taken by geostationary satellites, which orbit Earth at the same speed as Earth's rotation and so remain over the same spot on our planet. This allowed the scientists to track the variability in cloud cover blocking Earth's surface in West Africa during hurricane season.

The cloud cover acts as an indication of atmospheric disturbances. The more clouds in an area, the larger the disturbance. The scientists also measured the temperatures of the cloud tops, which grow colder the higher they rise.

"We first showed that the areal coverage of the cold cloud tops in tropical Africa was a good indicator of the monthly number of atmospheric disturbances-or waves-leaving the west coast of tropical Africa," said Price. "The disturbances that developed into tropical storms had a significantly larger area covered by cold cloud tops compared with non-developing waves."

Only about 10 percent of the 60 disturbances originating in Africa turn into hurricanes. However, the scientists did find that the spatial coverage of thunderstorms in West Africa can foretell the intensity of a hurricane a week later. This, in particular, can allow researchers to make better predictions so that cities and towns are better prepared.

The findings are published in the journal Geophysical Research Letters.

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