for National Geographic News
New Orleans avoided a worst-case pounding from Hurricane Katrina, but not by much.
It appeared Sunday night that the low-lying city would take a direct hit from a Category Five hurricane. As late as 11 p.m. Sunday, the hurricane had winds of 160 miles (260 kilometers) an hour.
But just before landfall Katrina's strongest winds died down slightly, said Randy McKee, the meteorologist in charge of the U.S. National Weather Service's office in Mobile, Alabama.
As the hurricane neared Grand Isle, Louisiana, and the mouth of the Mississippi River, a new eye wall started forming around the storm's existing eye.
This event, known as an eye-wall replacement cycle, occurs in extremely powerful hurricanes. It causes the storm's strongest winds to weaken temporarily as the new eye forms and the old eye disintegrates.
"It looks like it was going through one of those cycles right before landfall, taking it down from a Category Five to a Category Four," McKee said.
Still, the weakened hurricane inflicted massive damage as it made several landfalls, starting when it crossed Grand Isle around 5 a.m. local time. At that point the storm's strongest winds were blowing at 150 miles (225 kilometers) an hour, McKee said.
The hurricane's eye passed just to the east of New Orleans as it moved briefly back out over the waters of the Gulf of Mexico.
When Hurricane Katrina made another landfall, near the Louisiana-Mississippi border, its winds were down to around 140 miles an hour, McKee said.
The hurricane's front-right quadrant, which contained its strongest winds, pushed a storm surge of more than 20 feet (6 meters) into the Mississippi coast near Biloxi. That was the biggest storm surge in Mississippi since 1969, when monster Hurricane Camille drove a surge of more than 25 feet (7.7 meters) into Pass Christian, Mississippi.
Emergency management officials in New Orleans feared that Hurricane Katrina would send a storm surge over the tops of the levees protecting the city.
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