TC Watch > TC Classification [Refresh] [中文]
 Classification of Tropical Cyclones by Strength |
The following table lists the tropical cyclone categories used by various meteorological agencies:
Wind Speed (km/h) |
Beaufort Scale |
Central Pressure* (hPa) |
Classification |
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JMA (10-min average) |
HKO (10-min average) |
CMA (2-min average) |
CWB (10-min average) |
JTWC (1-min average) |
NHC (1-min average) |
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<41 |
<6 |
--- |
Tropical Depression |
Low Pressure Area |
--- |
Tropical Depression |
Tropical Disturbance |
Tropical Disturbance |
41-62 |
6-7 |
1000 |
Tropical Depression |
Tropical Depression |
Tropical Depression |
Tropical Depression |
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63-87 |
8-9 |
990-999 |
Tropical Storm |
Tropical Storm |
Tropical Storm |
Tropical Storm |
Tropical Storm |
Tropical Storm |
88-117 |
10-11 |
980-989 |
Severe Tropical Storm |
Severe Tropical Storm |
Severe Tropical Storm |
Severe Tropical Storm |
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118-153 |
12 |
960-979 |
Typhoon |
Typhoon (up to 149 km/h) |
Typhoon (up to 149 km/h) |
Typhoon (up to 183 km/h) |
Typhoon |
Hurricane Category 1 |
154-177 |
945-959 |
Severe Typhoon (150 to 184 km/h) |
Severe Typhoon (150 to 183 km/h) |
Hurricane Category 2 |
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178-209 |
930-944 |
Super Typhoon (from 185 km/h) |
Super Typhoon (from 184 km/h) |
Severe Typhoon |
Major Hurricane Category 3 |
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210-240 |
915-929 |
Major Hurricane Category 4 |
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241-249 |
905-914 |
Super Typhoon |
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>250 |
<905 |
Major Hurricane Category 5 |
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* Central Pressure refers to NW Pacific standard.
| Dvorak T-Number |
Dvorak technique is a method developed by meteorologist Vernon Dvorak to estimate the intensity of tropical cyclones based on satellite imageries. A T-Number is given to a tropical cyclone after analysis which is used to approximate its strength in terms of wind speed and pressure.
T-Number |
Wind speed |
Central Pressure in NW Pacific (hPa) |
Classification (HKO, NHC & JTWC mixed) |
Example (all examples except those for T7.5 are taken from the 2005 or 2006 seasons) |
1.0 |
<46 km/h, <25 kt |
--- |
Low Pressure Area |
(Most storms with at most T1.5 are not given names because they do not meet the criteria of a tropical storm, and are thus not upgraded by the JMA). |
1.5 |
Tropical Depression |
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2.0 |
55 km/h, 30 kt |
1000 |
Tropical Depression |
TD Trami |
2.5 |
65 km/h, 35 kt |
997 |
Tropical Storm |
TS Rumbia |
3.0 |
83 km/h, 45 kt |
991 |
Tropical Storm |
TS Jelavat |
3.5 |
102 km/h, 55 kt |
984 |
Severe Tropical Storm |
STS Bilis |
4.0 |
120 km/h, 65 kt |
976 |
Typhoon Cat. 1 |
TY Maria |
4.5 |
143 km/h, 75 kt |
966 |
Typhoon Cat. 1 |
TY Bolaven |
5.0 |
167 km/h, 90 kt |
954 |
Typhoon Cat. 2 |
TY Kaemi |
5.5 |
189 km/h, 102 kt |
941 |
Typhoon Cat. 3 |
TY Utor |
6.0 |
213 km/h, 115 kt |
927 |
Typhoon Cat. 4 |
TY Khanun |
6.5 |
235 km/h, 127 kt |
914 |
Typhoon Cat. 4 |
TY Chebi, Durian, Xangsane, Chanchu |
7.0 |
259 km/h, 140 kt |
898 |
Super Typhoon Cat. 5 |
TY Saomai, Ioke, Yagi, Cimaron |
7.5 |
287 km/h, 155 kt |
879 |
Super Typhoon Cat. 5 |
TY Ivan (1997), Joan (1997), Zeb (1998), Dianmu (2004), Chaba (2004) |
8.0 |
315 km/h, 170 kt |
858 |
Super Typhoon Cat. 5 |
(No TCs of T-Number 8.0 have ever formed) |
| Classification of Tropical Cyclones by Size |
Tropical cyclones can also be classified according to its size. A list is given as follows.
| Size | Radius in Degrees Latitude | Radius in Conventional Units |
| Midget / Very small (迷你) | < 2 | < 220 km / 120 nm |
| Small (小型) | 2 - 3 | 220 - 335 km / 120 - 180 nm |
| Average / Medium (中型) | 3 - 6 | 335 - 665 km / 180 - 360 nm |
| Large (大型) | 6 - 8 | 665 - 890 km / 360 - 480 nm |
| Very large (特大) | > 8 | > 890 km / > 480 nm |
Last Accessed: Sat Jul 27 2024 18:28:12 HKT
Last Modified: Mon Jul 24 2023
