Now Katrina and the possible wipe out of NO...
In these events, the U.S. government should consider detonating a low yield tactical nuke at the storms center....heat from the blast could evaporate a good portion of the storm and/or mitigate it's affects....if it's plausible the storm would destroy a U.S. city anyway...might as well nuke it...IMHO (of course I offer no scientific evidence it would work...but it's a thought.)