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Katrina's weakening--worst missing New Orleans

By: Dr. Jeff Masters, 11:39 AM GMT on August 29, 2005

Katrina is due south of the Mississippi-Louisiana border, and moving northward at 15 mph. On this course, the western edge of the eyewall will pass some 20 miles to the east of New Orleans, sparing that city a catastrophic hit. As the eye passes east of the city later this morning, north winds of about 100 mph will push waters from Lake Pontchartrain up to the top of the levee protecting the city, and possibly breach the levee and flood the city. This flooding will not cause the kind of catastrophe that a direct hit by the right (east) eyewall would have, with its 140 mph winds and 15-20 foot storm surge. New Orleans will not suffer large loss of life from Katrina.

Biloxi and Gulfport Mississippi will take the full force of Katrina's right eyewall, and a storm surge of 15-20 feet is likely along the central Mississippi coast. Katrina is a strong but weakening Category 4 hurricane, and will probably come ashore about noon CDT near Gulfport as a weak Category 4 hurricane with 135 mph winds. The storm has been slowly weakening the past 12 hours, with the central pressure rising more than 1mb/hour on average. The central pressure measured by the Hurricane Hunters has been oscillating the past three hours, jumping from 918 mb to 925, then back to 920, and now 921 mb at 7:30am EDT. The winds measured at flight level on the east side of the eyewall were 134 kt, which translates to 140 mph at the surface. The cloud pattern in satellite imagery has decreased on the west side due to dry air entrainment, and the eyewall has opened up to the south and southwest in radar imagery. With the center passing over mixed swamplands and water, much of the energy that sustains the hurricane will be cut off, making any further intensification unlikely. Katrina is not hitting at maximum intensity and is sparing New Orleans a direct hit, and although the damage will be incredible, it could have been much, much worse.

Tropical Depression 13
A new tropical depression formed in the mid-Atlantic yesterday, and is headed northwest over open ocean. This is one we definitely do not need to worry about for now. The storm may even dissipate due to hostile wind shear within the next few days.

Dr. Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.