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Gustav storms ashore southwest of New Orleans

By: Dr. Jeff Masters, 1:06 PM GMT on September 01, 2008

Hurricane Gustav is making landfall on the Louisiana coast just southwest of New Orleans as a powerful Category 2 hurricane. Latest data from the Hurricane Hunters at 8:30 am EDT shows that Gustav continues to weaken, with the pressure now 957 mb, and no surface winds above Category 2 strength observed. Cold water that the hurricane stirred up from the depths plus the effects of wind shear caused the eyewall to collapse a few hours before landfall, resulting in weakening. However, the hurricane reacted to collapse of the eyewall by broadening its wind field, spreading out the strongest winds over a wider area. The diameter of coastline being subjected to tropical storm force winds is now 440 miles, the same as Katrina. Hurricane force winds will be felt by a 115 mile-wide stretch of coast (Katrina's reach was 205 miles). Gustav remains a huge and powerful storm whose winds and storm surge will cause a tremendous amount of damage as the storm blasts through Louisiana today.


Figure 1. The tide gauge at Shell Beach, on the east side of New Orleans in Lake Borgne, recorded a storm surge over 7 feet as of 8 am EDT today. Image credit: NOAA Tides & Currents.

The main concern from Gustav is the storm surge. NHC is still predicting a 10-14 foot storm surge along the east side of New Orleans (Figure 2). This storm surge is characteristic of a Category 3 hurricane, providing a significant test of New Orleans' rebuilt levee system. Recent tide gauge readings from the east side of New Orleans show that a storm surge in excess of 7 feet has already occurred in Lake Borgne (Figure 1).

The satellite appearance of Gustav is slowly degrading. Visible satellite loops show Gustav has no eye, but still has an impressive amount of heavy thunderstorms. New Orleans radar shows some very heavy rain occurring in spiral bands rotating ashore, and several rotating tornadic thunderstorms have developed in these bands this morning, triggering tornado warnings. No confirmed tornadoes have been reported yet. Top winds measured at the surface were at the mouth of the Mississippi River at Pilot's Station East, which reported sustained winds of 91 mph, gusting to 117, at a height of 24 meters at 4 am CDT.


Figure 2. Predicted storm surge from NHC's experimental storm surge model.

From wunderground user NOLACANEWATCHER at 8 am EDT today:
I just wanted to let y'all know amazingly I still have power. My anemometer is clocking winds of 82.45 mph and my pressure is at 964mb. A gigantic branch has hit the corner of my house and there is massive damage to that area of the roof.

I'll have a full update on Gustav and Hanna this afternoon. Hanna is expected to hit the U.S. East Coast on Thursday or Friday this week.

New Orleans radar
New Orleans weather
Wunderground Tornado page

Jeff Masters
Gustav on Mobile Bay
Gustav on Mobile Bay
Rain band from Gustav moving west across Mobile Bay on Sunday afternoon.

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

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