- A subtropical cyclone in which the maximum sustained surface wind speed is 33 kn (38 mph or 62 km/h) or less. Subtropical Storm A subtropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) is 34 kn (39 mph or 63 km/h) or more. Super Typhoon (CMA) A term used by the China Meteorological Administration to describe a typhoon in the Western Pacific that has sustained windspeeds greater than over a 3-minute period Super Typhoon (HKO) A term used by the Hong Kong Observatory to describe a typhoon in the Western Pacific that has sustained windspeeds greater than over a 10-minute period Super Typhoon (JTWC) A term used by the Joint Typhoon Warning Center in the Western Pacific to describe a typhoon that has sustained windspeeds greater than 130 knots over a 1-minute period. Super Typhoon (PAGASA) A term used unofficially by PAGASA in the Western Pacific for tropical cyclones with 10-minute sustained winds of more than . Synoptic Track Weather reconnaissance mission flown to provide vital meteorological information in data sparse ocean areas as a supplement to existing surface, radar, and satellite data. Synoptic flights better define the upper atmosphere and aid in the prediction of tropical cyclone development and movement. T Tropical cyclogenesis The development and strengthening of a tropical cyclone in the atmosphere. Tropical cyclogenesis involves the development of a warm-core cyclone, due to significant convection in a favorable atmospheric environment. There are six main requirements for tropical cyclogenesis: sufficiently warm sea surface temperatures, atmospheric instability, high humidity in the lower to middle levels of the troposphere, enough Coriolis force to develop a low pressure center, a preexisting low level focus or disturbance, and low vertical wind shear. Tropical cyclone A warm-core non-frontal synoptic-scale cyclone, originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation about a well-defined center. Once formed, a tropical cyclone is maintained by the extraction of heat energy from the ocean at high temperature and heat export at the low temperatures of the upper troposphere. In this they differ from extratropical cyclones, which derive their energy from horizontal temperature contrasts in the atmosphere (baroclinic effects). Tropical cyclone (Southwest Indian Ocean) A tropical system in which the 10-minute maximum sustained winds are between . Tropical depression A tropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average)