I blogged about this between hurricanes, and was in New Orleans to see the mess. It is not hard. Hurricanes only happen when the air is over 30oC.
So the trick is to pass the heat of the air into the sea – where is flows towards the Poles – where that heat is needed.
We have a Carnot gas (Ammonia is fairly cheap). We pressurise it, and it get mad hot! We pass that heat into the sea. When we vent the pressure the gas gets cold. So we have an Aluminium helix in the air, sucking heat from the air. So the Carnot gas ends up at 25oC – too cold for a hurricane.
Incoming hurricanes are deflected away from the city. We double the pressure on the gas. The gas ends up at 573oC. This passes through a stainless steel helix in the seas – Dr Z's ideas. So we boil off a lot of sea water, which flows as high cloud, increasing rain fall around the globe.
So New Orleans is warm – but no damn hot. And no hurricanes. We can use this idea around the globe, to deflect hurricanes/tornadoes away from centres of human population.