Therein lies the problems. One, water doesn't move that fast across the Gulf; researches have been tracking the discharge from rivers & cities due to Katrina's impact and its impacts could only be felt across part of the northern Gulf even a month after the fact, all regulated by the eddies. You aren't going to cool water across the entire basin that quickly with anything unless you spread it across the entire Gulf. That's just not feasible, even if it weren't asking for an ecological disaster.

Two, you don't know the repercussions of such an activity. Many people depend upon the Gulf for a living. Drastic and sudden changes to the ecosystem in the Gulf can disrupt that -- sometimes permanently. The result of the change, even if it were as simple as you believe it to be (which it isn't), could be as negative as a hurricane would be.

The best way to save lives and property is not to attempt to modify these storms by regulating their environment, a largely impossible and impractical task, but instead to educate people about their impacts, urge them to take precautions for any storm to protect both life and property, and adhere to stronger and smarter building codes, among other activities. It's much less costly, has no impact upon the environment or ecosystem of the region, and achieves the exact same goal.