Tropical Cyclone Scales - Western Pacific

Western Pacific

RSMC Tokyo's
Tropical Cyclone Intensity Scale
Category Sustained winds
Typhoon ≥64 kt
≥118 km/h
Severe
Tropical Storm
48–63 kt
89–117 km/h
Tropical Storm 34–47 kt
62–88 km/h
Tropical
Depression
≤33 kt
≤61 km/h

Any tropical cyclone that develops within the Northern Hemisphere between 180° and 100°E in the Northern Hemisphere, is monitored by the Japan Meteorological Agency's Regional Specialized Meteorological Center in Tokyo, Japan, on behalf of the WMO/ESCAP's Typhoon Committee. Other warning centres such as the Philippine Atmospheric, Geophysical and Astronomical Services Administration, the China Meteorological Agency and the Hong Kong Observatory also monitor tropical cyclones developing within the basin.

Official classifications

All classifications from RSMC Tokyo are based on 10-minute maximum sustained wind speed. The lowest category is a tropical depression having wind speed under 33 kn (38 mph; 61 km/h), while a tropical storm has wind speed between 34 kn (39 mph; 63 km/h) and 47 kn (54 mph; 87 km/h). A severe tropical storm has wind speed between 48 kn (55 mph; 89 km/h) and 63 kn (72 mph; 117 km/h), while the highest category is a typhoon having wind speed above 64 kn (74 mph; 119 km/h).

For own purposes, RSMC Tokyo unofficially divides the typhoon category into three categories, with a strong typhoon having wind speed between 64 kn (74 mph; 119 km/h) and 84 kn (97 mph; 156 km/h). A very strong typhoon has wind speed between 85 kn (98 mph; 157 km/h) and 104 kn (120 mph; 193 km/h), while a violent typhoon has wind speed over 105 kn (121 mph; 194 km/h).

Other classifications

Some of the members of the typhoon committee use scales varying from the Typhoon Committees one. Both the CMA and the HKO use the Typhoon Committees scale but divide their classifications of typhoons into severe and super when wind speed reaches 81 kn (93 mph; 150 km/h) or 100 kn (120 mph; 190 km/h)., while the CMA also adopts a lower limit of Beaufort Force 6 for a tropical depression.

Both the Joint Typhoon Warning Center and the PAGASA merge the severe tropical storm into the tropical storm category, yet the JTWC has the super typhoon category when wind speed reaches 130 kn (150 mph; 240 km/h). In addition, the Central Weather Bureau has its own scale in Chinese but uses the Typhoon Committee scale in English.

Although most of agencies use 10-minute maximum sustained wind speed, the JTWC uses 1-minute maximum sustained wind speed and the CMA uses 2-minute maximum sustained wind speed.

Read more about this topic:  Tropical Cyclone Scales

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