Over warm tropical oceans, organized thunderstorms can coalesce into a rotating storm with sustained winds of at least 74 miles per hour. In the Atlantic and eastern Pacific that storm is called a hurricane. The same type of system is known as a typhoon or cyclone in other basins.

A clear eye often forms at the center, surrounded by a ring of intense thunderstorms called the eyewall. Spiral rain bands extend outward for hundreds of kilometers. The storm draws energy from the heat and moisture of the ocean surface.

Hurricanes produce destructive winds, torrential rain, and dangerous storm surge along coasts. Forecasting track and intensity has improved, yet rapid changes still challenge predictions. Evacuation decisions and building codes are designed around the threats these storms pose.

• Tropical cyclone with winds ≥74 mph
• Features eye and eyewall
• Produces wind, rain, and surge
• Forms over warm ocean water