Isaac, the probable damage is water

[Conan The Librarian]

There does seem to be a lot of hysteria around Isaac and the kind of damage that is likely. The emphasis should be on flooding, if it really does hit around New Orleans. I don't think that city will do well if hit with 11 or 12 inches of rain in one day. The wind shouldn't be much of a problem unless it really starts to speed up in a hurry.

[BBF]

Will that finally  settle the fate of this city or are more millions of $  wasted.

[Conan The Librarian]

I think it will be a test of whether they made the place storm-worthy with those 30 billion dollars or so that were spent on New Orleans after Katrina. The forecast is for 12 inches just between today and tonight. Not sure about tomorrow, but I would expect a lot more.
 
Those areas that were flooded for weeks last time should not be flooded for as long because levys shouldn't break this time. (at least on the theory that 30 billion will by some pretty fancy levys).