A potential hurricane goes through four basic phases before it attains hurricane strength. These are:
Phase 1 – Tropical Disturbance:
A system in the trade wind easterlies which gives rise to a discrete area of cloudiness with embedded showers and thunderstorms.
Phase 2 – Tropical Depression:
This system has definite counter-clockwise wind circulation in which maximum sustained surface wind is less than 61 km/h (38 mph).
Phase 3 – Tropical Storm:
This phase immediately precedes the hurricane. Tropical storms are systems with definite counter-clockwise wind circulation in which the maximum sustained surface wind is greater than 61 km/h (38 mph) but not more than 119 km/h (74 mph). It is at this stage the storm is given a name.
Phase 4 – Hurricane:
The final stage is the hurricane, with a maximum wind speed of 119 km/h (74 mph) and over. The system is now mature and the eye is well defined. If atmospheric conditions are right, it can strengthen.
This system has definite counter-clockwise wind circulation in which maximum sustained surface wind is less than 61 km/h (38 mph).
Source: https://www.odpem.org.jm/