Katrina’s strength downgraded
MIAMI – Katrina hit the Gulf Coast as a Category 3 hurricane, not a Category 4 as first thought, and New Orleans and Lake Pontchartrain likely were spared the storm’s strongest winds, the National Hurricane Center said Tuesday.
New Orleans’ storm levees were generally believed to be able to protect the city from the flooding of a fast-moving Category 3 storm. But Katrina was generally a slow-moving storm, said Jim Taylor, a spokesman for the Army Corps of Engineers.
Parts of the levee system were either topped or failed, leaving up to 80 percent of the city under water.
Katrina made landfall Aug. 29 with top sustained winds of about 125 mph, not the 140 mph that was calculated at the time, the hurricane center said in its final report on the hurricane.
New Orleans was on the storm’s west side, which normally has weaker wind. Although an accurate reading of the highest wind in the New Orleans area was made difficult by the failure of measuring stations, a NASA facility in eastern New Orleans measured sustained wind of about 95 mph, the report said.
Most of the city likely experienced winds of Category 1 or 2 strength, ranging from 74 mph to 110 mph, the report said, although wind on the upper floors of high-rise buildings could have been a category higher.
Taylor said the levees that protect New Orleans were built before the creation of the Saffir-Simpson scale of classifying hurricanes, so different parts of the system protect against varying levels of wind speed, storm surge and barometric pressure.
An investigation into why the levee system failed is under way. Taylor said the change in category won’t affect the fixes being made now or plans for future changes, which are still being debated.
But Louisiana Sen. Mary Landrieu, a Democrat, said: “This news further highlights the need for a full federal commitment to build the highest level of protection through levees and coastal restoration for New Orleans, south Louisiana and the Gulf Coast.”
Category 3 storms range from 111 mph to 130 mph, so Katrina was on the higher edge of that ranking. Category 4 ranges from 131 mph to 155 mph. Katrina was a top-scale Category 5 with 175-mph winds while in the Gulf of Mexico.
The revision of Katrina’s strength came after forecasters studied data from devices that were dropped into the storm from aircraft. The change also came from reviewing readings from a device that measures speed by examining how sea foam is blown.
Katrina killed more than 1,300 people in Louisiana, Mississippi, Florida, Georgia and Alabama. It is expected to cost insurers at least $34.4 billion in claims.