It is relative to land mass, cloud saturation, and guessing. Katrina was out in the Gulf for days and the water was built up in walls or waves. Jaimaca and surrounding areas are in danger, but the major danger is from mountain run off rather than days of the storm sitting in one place and spinning. There are other geographic differences, but I can tell you that parts of Central Florida can receive 6 inches of rain in one afternoon thunderstorm, and although there will be urban street flooding until the runoff subsides, there is not really a lot of problems, because people have already adjusted. Even those silly pictures in Miami in the early rainy season only last about 2 hours at the most unless there are some serious storm drainage stopped up with fast food garbage bags and beer cans.