Stages and Categories of Hurricanes

7/24/2019 (Permalink)

As a storm builds from a thunderstorm to a hurricane, it passes through 4 distinct stages:

1. Tropical Disturbance: a mass of thunderstorms that have wind speeds of less than 23 mph.
2. Tropical Depression: consistent wind speeds of 23-39 mph and a circulation of wind in the center of the thunderstorm mass is detected.
3. Tropical Storm: forms when the maximum sustained winds have intensified to 39-73 mph. Storms are typically given a name at this stage and are characterized by problems caused from very heavy rainfall.
4. Hurricane: finally forms when surface pressures continue to drop, and winds reach 74 mph. There is now a clear and definite rotation around a calm center, or eye.

Hurricanes have their own categories which are defined by the Saffir Simpson Hurricane Wind Scale:

Category 1: Winds 74 to 95 mph (Minor damage)

Category 2: Winds 96 to 110 mph (Extensive damage — Can uproot trees and break windows)

Category 3: Winds 111 to 129 mph (Devastating — Can break windows and doors)

Category 4: Winds 130 to 156 mph (Catastrophic damage — Can tear off roofs)

Category 5: Winds 157 mph or higher (Can level houses and destroy buildings)