Massive hurricanes are formed from the progression of tropical thunderstorms. Certain conditions need to be met to enable the storm to thrive to a significant level of power and strength.
As a first probable cause, several thunderstorms start circulating around a central area of warm water. This ocean water is a source of energy, and as long as the hurricane has either that source, or warm moist air, it will continue to thrive. The warm air will start to evaporate rapidly to form thick clouds and rain. The high pressured air is then sucked into the center of the storm. When the wind speed in the storm reaches 74mph or more, it is then considered a hurricane.