Hurricane Andrew of 1992 made landfall over southern Miami-Dade County, Florida causing 26.5 billion dollars in losses--the costliest hurricane on record.
Records are made to be broken. Compared to Katrina, Andrew will seem like just another tropical storm.
You're right. I heard a meteorologist say that when they get that big they are their own "weather system," and they make the weather, other systems do not have an effect on them.