Tropical Cyclones
Tropical Depressions; Tropical Storms; Storm Surge Tropical depressions are organized systems of clouds and thunderstorms with a defined circulation and with maximum sustained winds of 61km/hr (38mph) or less. Tropical storms are organized systems of clouds and thunderstorms with a defined circulation and with maximum sustained winds of 63 - 117 km/hr (39-73mph) or less. A storm surge is a large dome of water that sweeps across the coastline near where a hurricane makes landfall. It is often 50-100 miles wide.