NHC's Knabb: For many folks in Gulf Coast, Isaac is not even half over

Despite making landfall twice in the overnight hours, Hurricane Isaac is a very slow moving storm. National Hurricane Center's Richard Knabb tells Soledad O'Brien on "Starting Point" this morning that Hurricane Isaac's fierce winds and rainfall is far from over.

"For many people it's not even half over," Knabb says. "You're not seeing the center pass by you yet and once it does, you still have the southern half of the circulation to go. And this really slow motion overnight has really pointed out how long a duration this is going to be. It's still only moving at six miles per hour. So it is the large size and the slow motion that makes this category 1 hurricane seem worse than the category would tell you because the category only reflects the maximum sustained wind and for this one it's 80 miles per hour."

"But the rainfall, the storm surge and duration of the winds and duration of the rains, all of these things are not captured by the category. And for many people it's going to be all day today and into tonight and into tomorrow that the rains and the onshore flow causing the storm surge are going to persist," Knabb adds.