As Isaac nears hurricane strength, New Orleans braces for flooding (+video)

Isaac was on the verge of ballooning into a hurricane Tuesday that could flood the coasts of four states with storm surge and heavy rains on its way to New Orleans, where residents hunkered down behind levies fortified after Katrina struck seven years ago this week.

Shelters were open for those who chose to stay or missed the chance to get away before the outer bands of the large storm blow ashore ahead of a forecast landfall in southeast Louisiana on Tuesday night or early Wednesday.

The U.S. National Hurricane Center in Miami predicted Isaac would power up to hurricane strength, which starts at winds of 74 mph, later in the day and be at least a Category 1 hurricane by the time it's expected to reach the swampy coast of southeast Louisiana.

In Houma, a city southwest of New Orleans, people filled a municipal auditorium-turned-shelter. Simon and Crystal Naquin were there with their teenage sons because the camper they call home sits in a flood-prone spot between a navigation canal and lower Bayou Caillou.

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Simon Naquin said he rode out hurricanes when he was younger, but doesn't do that anymore since seeing the damage wrought by hurricanes Andrew, Katrina and Rita.

"Now that I got kids, I've seen too much to say, 'Stay,'" said Naquin, who shared a twin air mattress with his wife while their sons read and snacked on jambalaya amid a pile of blankets and next to a stash of water bottles and food.

Forecasters warned that Isaac was a large storm whose effects could reach out 200 miles from its center. Water may be worse than wind because the storm could push walls of water while dumping rain to flood the low-lying coast in Louisiana, Mississippi, Alabama and the Florida Panhandle.

The U.S. National Hurricane Center in Miami predicted Isaac would power up to hurricane strength, which starts at winds of 74 mph, later in the day and be at least a Category 1 hurricane by the time it's expected to reach the swampy coast of southeast Louisiana.

Isaac's track is forecast to bring it to New Orleans seven years after Katrina hit as a much stronger storm on Aug. 29, 2005.

This time, federal officials say the updated levees around the city are equipped to handle storms stronger than Isaac. The Army Corps of Engineers was given about $14 billion to improve flood defenses, and most of the work has been completed.

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