Typhoons

Typhoons are tropical cyclones that form in the Northwest Pacific Ocean. They develop over warm tropical waters and gain strength from moist air condensing. The term typhoon is used for storms in the western North Pacific; similar systems are called hurricanes in the Atlantic and eastern Pacific, and cyclones in the Indian Ocean and southern Pacific.

Formation requires sea surface temperatures around 26.5 C or higher, sufficient moisture, low vertical wind shear, and a pre-existing disturbance that can organize into a low-pressure center. Through stages of tropical depression, tropical storm, and then typhoon, rotation develops due to the Coriolis effect. An eye and eyewall may form in stronger storms.

Strength scales differ by agency. In many parts of the Western Pacific, a storm is called a typhoon once sustained winds reach tropical storm thresholds; “super typhoon” is used for exceptionally intense systems by some warning centers. The Japan Meteorological Agency reports winds as 10-minute sustained winds, while others use 1-minute measures.

Forecasting relies on satellites, radar, weather buoys, aircraft reconnaissance, and numerical models. The Japan Meteorological Agency and the Joint Typhoon Warning Center issue advisories, while national meteorological services distribute warnings. Preparedness includes evacuations, building codes, and coastal defenses.

Impacts include strong winds, heavy rainfall, flooding, landslides, and coastal storm surge. Losses depend on intensity, track, population density, and preparedness. Regions frequently affected include East and Southeast Asia, the Philippines, Taiwan, and parts of Oceania.

Names are assigned by the WMO Typhoon Committee from lists contributed by member countries. Typhoon activity in the western North Pacific occurs year round, with a peak typically in late summer and early autumn.