Isaac became a hurricane as forecast on Tuesday and slowed in its approach towards the Louisiana coastline. Hurricane Isaac came ashore for a brief time on Tuesday evening in the southeast of the state in Plaquemines Parish, around 90 miles southeast of New Orleans, before heading back over the Gulf of Mexico and moving slowly in a northwest motion towards a second landfall which it has yet to make. Maximum sustained winds remain around 80mph making Isaac a Category 1 hurricane.
Storm surge is one of the main threats Isaac is bringing to Louisiana and the surrounding coastline. The National Hurricane Centre continues to warn of a storm surge of 6 to 12 feet along the immediate coastline where Isaac makes landfall and onshore winds are a factor. The fact the Isaac has slowed considerably and is wobbling just offshore means that any storm surge impact is likely to have been exacerbated and there could be some quite extensive flooding in low land areas. A storm surge of 11 feet has been reported at Shell Beach, Louisiana.
To add to the sea water flood threat for the coastline, Isaac is also being seen to blow the waters of the Mississippi river back upstream raising concerns about some of the levees which protect the area from river flooding. High winds are reported to have been backing up the Mississippi and the levee at the top of the Pointe à la Hache ferry landing is said to be within a foot or two of the water now. New Orleans itself has much improved flood defences since Katrina so it has to be hoped that they will be sufficient for a hurricane like Isaac.
Hurricane Isaac s now heading for its second landfall which is expected to happen overnight near Grand Isle. Due to the slow movement of the storm rainfall totals of as much as 20 inches are expected in some areas and these will add to flooding concerns, particularly if it coincides with the peak expected storm surge of 12 feet.
It seems that there are areas outside of where the levees have been strengthened for hurricanes which are now at risk. The National Weather Service has warned about areas such as Lakes Pontchartrain and Maurepas and said that sections of the west Jefferson, east St. Charles and lower Lafourche hurricane protection levees could be topped. Any levees that are breached will cause extensive flooding and property damage.
More than 300,000 houses and businesses in Louisiana are said to be without power as the storm comes ashore. Much of the state has shut down with airports, schools and essential services closed until the storm passes.
The core of hurricane Isaac is expected to pass to the west of New Orleans and head for Baton Rouge early Wednesday (local time). Due to the slow movement, large size and extra time spent over the Gulf, it is expected that Isaac will weaken slowly as it moves inland so strong winds will impact areas well inland from the coast. The rainfall threat is expected to spread far inland and the storm surge will test defences the most at high-tide on Wednesday morning.
Our next articles on hurricane Isaac will likely be on the aftermath and any insurance and reinsurance losses which result from the storm. Read our article on the exposure insurers, reinsurers and catastrophe bonds have to hurricane Isaac.
The current location of Isaac and the hurricanes forecast path can be seen below: