Although both officially a category 3 storm at, or close to, landfall, Gustav is a very different storm to Katrina. The main differences are in size and central pressure, as well as track. Katrina passed 40 miles or so to the east of New Orleans, and Gustav should remain 50 miles + to the west of New Orleans. Also, Katrina’s wind field was much bigger than Gustav’s, with hurricane force winds extending 110 miles, compared to Gustav’s 70 miles.

 In addition, Katrina’s sustained winds were near 127 mph, compared to Gustav’s 115 mph, and more notably Katrina’s minimum central pressure at landfall was a very intense 920 mb – the 3rd lowest recorded for a landfalling hurricane. Gustav’s is 956 mb. In addition, out in the Gulf of Mexico, Katrina had been a severe category 5 hurricane with sustained winds up to 175 mph at its peak, and affected the offshore platforms with category 4 and 5 winds.

 Gustav has been a moderate category 3 through most of its track through the offshore platforms. The maximum significant wave height recorded for Katrina was 55 feet in the Gulf, which was the highest ever recorded, and so far for Gustav has been 30 ft.

Katrina’s storm surge was 24-28 feet along the western Mississippi coast across a path of about 20 miles, tapering to a height of 17-22 feet along the eastern MS coast. The maximum high water mark observation was 27.8 feet at Pass Christian, MS. Surges in eastern Louisiana generally ranged from 10 to 19 feet. For Gustav we are expecting maximums of around 13 ft in the landfall area, and 6-9 feet in eastern Louisiana.

Rainfall was not a driver of the loss or damage for Katrina, although up to 20-40 inches of rainfall in total were recorded in several locations across Louisiana, parts of Mississippi, and western Tennessee and Kentucky as the remnants of Katrina moved inland. Gustav is forecast to produce similar amounts of up to 20 inches in western Louisiana and eastern Texas, although if it stalls inland, rainfall totals could be more.

from rms.com