Isaac threatens Gulf Coast with hurricane sized storm surge

Our latest article on Hurricane Isaac can be found here. Tropical storm Isaac is approaching the key oil and gas producing region of the Gulf of Mexico as it continues to make its way towards the Louisiana coastline. Currently carrying maximum sustained winds of 70mph, Isaac remains a tropical storm, having been slower to intensify that was expected. The current forecast shows Isaac reaching hurricane status later today before moving through the Gulf oil fields and bearing down on the Louisiana coast where the storm is forecast to make landfall around 7pm local time on Tuesday.

The forecast predicts that Isaac will have intensified into a hurricane with 90mph sustained winds by the time it makes landfall. Isaac has been slower to intensify that was originally thought due to the huge size of the storm, tropical storm force winds extend outwards over 200 miles from the center. The size of Isaac now means that there is a very real threat of a large storm surge along the Louisiana coastline which could cause extensive flooding, especially when combined with very high levels of rainfall.

Southeast Louisiana and Mississippi are forecast to have a storm surge of 6 to 12 feet, Alabama 6 to 9 feet, south-central Louisiana and the Florida Panhandle 3 to 6 feet and the west coast of Florida 1 to 3 feet. A storm surge of that size can bring significant flooding to coastal and low lying areas. Much of the Louisiana coastline is very flat with low sea defences so there is a real concern that if the storm surge hits during the high tide damage has the potential to be extensive in exposed areas. Accompanied by 6 to 18 inches of rainfall, there is a very real flood threat emerging with this storm.

Risk analytics firm Core Logic have estimated that there is more than $27 billion in potential exposure to residential property damage along the Gulf Coast from projected hurricane Isaac storm surge. Those are worst case figures but show the extent of the exposure in the Gulf Coast area to storm surge alone, so not taking into account wind damage, flooding and other impacts further inland.

Given the size of hurricane Isaac the storm is likely to cause disruption and damage far inland after landfall. Rainfall impacts will continue for some time as Isaac dissipates inland with flood threat occurring far from the coast. Isaac’s winds will be sufficiently strong to cause widespread damage around the area it makes landfall.

The exact location of Isaac’s landfall and exactly how strong the storm will be is a subject of some debate. Forecasters have found it very hard to pin down the exact track that Isaac will follow and some uncertainty still remains.

We will update further on Isaac should the storm strengthen considerably more than forecast. You can see the current location of tropical storm Isaac below and track the storms progress on our 2012 Atlantic Hurricane Season page.

Tropical storm / hurricane Isaac forecast path