How Hurricanes Form — From Tropical Wave to Category 5

Ingredients for a Hurricane

1. Warm ocean water — at least 26°C to a depth of 50 metres
2. Atmospheric instability — warm, moist air rising rapidly
3. Low wind shear — consistent winds at different altitudes so the storm structure is not torn apart
4. Distance from the equator — at least 5° latitude so the Coriolis effect can start rotation

The Formation Process

Stage 1: Tropical Disturbance — A cluster of thunderstorms organises over warm water, often starting as an African easterly wave crossing the Atlantic.

Stage 2: Tropical Depression — Sustained winds reach 62 km/h. The system develops a closed circulation. It gets a number.

Stage 3: Tropical Storm — Winds reach 63-118 km/h. The storm gets a name. Rain bands spiral outward.

Stage 4: Hurricane — Winds exceed 119 km/h. An eye forms at the centre — a calm, clear column surrounded by the most intense winds (the eyewall).

The Saffir-Simpson Scale

Why Hurricanes Weaken

Hurricanes lose power when they move over cool water, encounter wind shear, or make landfall (cut off from their warm-water fuel source).

---

Monitor tropical weather on Weather Tomorrow.