Tropical Storm Isaac over Gulf of Mexico early Monday (Credit: NOAA/National Hurricane Center)

Hurricane Isaac is lashing Southeast Louisiana, including New Orleans. Torrential rain and strong winds are also battering Coastal Mississippi and Alabama.

Authorities say a storm surge driven by Isaac pushed water over the top of an 18-mile stretch of levee in a thinly populated part of Plaquemines Parish.

The levee is one of many in the low-lying coastal zone. It is not part of New Orleans' defenses.

Plaquemines officials believe some people may be trapped in their homes by the flood but they are not sure how many might still be in the area. Strong wind was hampering rescue efforts.

The massive storm spans nearly 200 miles and has maximum sustained winds of 75mph near its center.

Meteorologist Branden Borremans says, Isaac will take a while to loosen its grip on the Gulf Coast. Branden says the slow movement and track along the coast will keep flooding a major concern in Louisiana, Mississippi, and Alabama.

Up to 20" of rain will be possible through Friday in Southeast Louisiana (including New Orleans) and Southern Mississippi. A few spots might even pick up more than 20" of rain! When it's all said and done, many areas will have seen more rain from Isaac than from Katrina in 2005. However, storm surge flooding with this storm will fall well short of levels reached by Katrina.

Conditions will GRADUALLY improve over this area Thursday and Friday, as Isaac weakens and slowly pulls to the north.