Part 1's link is here.
From "Experts: Katrina may have been weaker than first thought":
...When Katrina struck the mouth of the Mississippi River south of New Orleans at daybreak on Aug. 29, it was a Category 4, with wind speed of 135 mph, [Jack Beven, hurricane specialist with the National Hurricane Center in Miami] said. The strongest part of the storm actually missed New Orleans but instead passed over the mouth of the Mississippi River and into the Mississippi Gulf coast.
"From 20 to 70 miles east to northeast of New Orleans, that's where the worst effects of the storm were, winds and tides, over on the Mississippi Gulf coast - Gulfport, Biloxi, Waveland, Pass Christian and even over to Ocean Springs," Beven said. "The winds and the tides there were much higher than what you had in the New Orleans area."
Beven said the hurricane center is internally debating whether Katrina was a Category 3 or 4, and specifically where. The center is examining data from the National Oceanic and Atmospheric Administration and Air Force hurricane hunter aircraft that flew through the eye and the strongest winds of the hurricane many times on the 29th.
"We were getting a continuous flow of data ... the data is taken automatically every 20 or 30 seconds. That's one reason we haven't finished yet, there's a lot of data to evaluate," Beven said.
Scientists are also investigating why a 20-to-30-foot storm surge along the Mississippi coast seemed more consistent with a Category 5 hurricane than the designated Category 4, according to specialists at the hurricane center.
"At one point Katrina was a Category 5. It may have been that the winds died down to a Category 4 or 3, but the ocean was so stirred up by the hurricane that the surge was more equivalent to a 5," Beven said...