Storm Thrashes Gulf Coast

Katrina was a marginal hurricane with peak winds of 95 mph when it plowed into Florida's Atlantic coast last week. Nonetheless, it was blamed for 11 deaths and caused extensive flooding near Miami and torrential rains in the Keys before spinning into the Gulf of Mexico and turning north.

There Katrina gained strength and definition, unimpeded by land masses that trigger the crosswinds that spread storms out and eventually rip them apart. "The warm Gulf waters provide extra octane," National Hurricane Center meteorologist Chris Sisko explained in a telephone interview from Miami.

By Sunday, Katrina was a Category 5 hurricane -- winds in excess of 155 mph. Experts were warning of apocalyptic damage to New Orleans, a city of 485,000 people, most of whom live below sea level.

Mayor Ray Nagin ordered a mandatory evacuation of New Orleans over the weekend, and an estimated 80 percent of residents complied. Those who remained behind were mostly visitors and tourists trapped because the airport had closed.

These stayed in hotels or went to emergency shelters. The biggest of these was the Superdome, but the American Red Cross also had about 30,000 people in shelters across the state.

Fortunately for New Orleans, Katrina peaked too soon. "When a storm becomes stronger, it pushes larger waves," said David S. Nolan, a meteorology professor at the University of Miami. The water temperature drops, and "the available energy starts to decline," he added.

Katrina dropped from a Category 5 to a strong Category 4, then "wobbled" slightly just before landfall, veering east from New Orleans when it hit the coast. Even so, National Weather Service Director David L. Johnson said, Katrina is quite likely to end up among the 10 strongest hurricanes to hit the continental United States.

"The city of New Orleans was fortunate in that the eye passed very slightly to the east," Johnson said in a telephone interview. "Because of the wind's circulation, it's the northeast quadrant that piles up the water, and had the track been even slightly west of north, the city would have been devastated."

Gugliotta reported from Washington. Staff writer Jonathan Weisman in Washington contributed to this report.