is 33 kn (38 mph or 62 km/h) or less. Tropical disturbance A discrete tropical weather system of ostensibly organized convection—generally 100 to 300 nmi in diameter—originating in the tropics or subtropics, having a non-frontal migratory character, and maintaining its identity for 24 hours or more. It may or may not be associated with a detectable perturbation of the wind field. Tropical storm A tropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) ranges from 34 kn (39 mph or 63 km/h) to 63 kn (73 mph or 118 km/h). Tropical Storm Warning An announcement that tropical storm conditions (sustained winds of 39 to 73 mph) are expected somewhere within the specified coastal area within 36 hours. Tropical Storm Watch An announcement that tropical storm conditions (sustained winds of 39 to 73 mph) are possible within the specified coastal area within 48 hours. Tropical wave A trough or cyclonic curvature maximum in the trade-wind easterlies. The wave may reach maximum amplitude in the lower middle troposphere. Tropical Weather Outlook (TWO) An official forecast by the National Hurricane Center highlighting the probability of a tropical cyclone developing. Typhoon A tropical cyclone with winds exceeding in the western Pacific Ocean, the equivalent of a hurricane W Western North Pacific Basin The portion of the North Pacific Ocean from 100E to 180E. The Joint Typhoon Warning Center in Pearl Harbor, Hawaii, PAGASA and the Japan Meteorological Agency are responsible for tracking tropical cyclones in this region. See also Glossary of climate change Glossary of meteorology Glossary of tornado terms References Tropical cyclone terms Wikipedia glossaries using description lists