U. storm expert seeks clues in West Africa

KAWSARA, Senegal — Ed Zipser knew Ernesto as a baby. The meteorologist flew through the weather system when it was just a patch of turbulence off the coast of West Africa. Ernesto then grew up to be the first hurricane of the 2006 season.

Scientists know that 4 out of 5 tropical storms hitting the United States — including the deadly and destructive hurricane Katrina a year ago — start out in the waters off Africa before blowing across the Atlantic.

What they don't really understand is why some systems fizzle and others whip up into monster hurricanes. So Zipser and his colleagues are in West Africa, trying to unlock the secrets of the storm as part of the NASA-backed study known as NAMMA (NASA African Monsoon Multidisciplinary Analyses).

Using a DC-8 jet, they fly through thunderstorms trying to map the precise contours with banks of sensors measuring wind speed and direction, cloud shapes and contents, rainfall rates, temperature, humidity, and atmospheric pressure.

"It's a bit like taking a bumpier-than-average commercial flight — you'd maybe spill a cup of coffee," says the storm expert from the University of Utah, describing his field research.

The scientists have also set up three state-of-the-art radars — one on the coast of Senegal, one on the Cape Verde Islands to the west, and another in landlocked Niger to the east.

Residents in the tiny Senegalese hamlet of Kawsara crane their necks to look at the radar that pokes its head up incongruously between the gingerbread-plum and cashew-nut trees that dot the scrubland.

The people of this area generally have a more traditional take on meteorology, banging drums or slaughtering a cow on the beach to summon the rains.

Now, 6 million pieces of electronic data are being collected on their doorstep every 15 minutes as scientists try to discover why 95 percent of West African storms collapse out at sea, and — more centrally — why the other 5 percent don't.

For about a month ending in mid-September, the NASA-backed researchers will collect information about the initial stages of a storm. Once the storm's life cycle is complete, and scientists know whether it ultimately intensified or weakened, they will look back over the early data and try to pick out the characteristics that gave birth to a big storm.