October 2004: Accumulated Cyclone Energy (ACE) Index*

Ocean Basin Tropical Cyclone Cyclogenesis Date Cyclolysis Date Saffir-Simpson Category Maximum 6-hr Sustained Wind (kt) Maximum 6-hr Wind Gust (kt) Accumulated Cyclone Energy (ACE) Index (kt2)*
Northwest Pacific
 Ma-On-04 10/4/04 10/9/04 Cat-5 140 170 17.77 x 104
Northwest Pacific
 Nock-Ten-04 10/16/04 10/26/04 Cat 3 110 125 29.64 x 104
Northwest Pacific
 Tokage-04 10/12/04 10/20/04 Cat 4 125 150 24.81 x 104
Northeast Pacific
 Kay-04 10/4/04 10/6/04 TS 40 50 0.16 x 104
Northeast Pacific
 Lester-04 10/11/04 10/13/04 TS 45 55 0.65 x 104
Atlantic
 Lisa-04 9/20/04 10/3/04 Cat 1 65 80 9.27 x 104
Atlantic
 Matthew-04 10/8/04 10/10/04 TS 40 50 0.77 x 104
Atlantic
 Nicole-04 10/10/04 10/11/04 Sub-TS 45 55 1.16 x 104


*The Accumulated Cyclone Energy (ACE) Index is calculated by summing the squares of the estimated 6-hourly maximum sustained wind speed in knots (Vmax2) for all periods in which the tropical cyclone is a tropical storm or greater intensity. For a complete description of the ACE Index see Bell et al. (2000), Bulletin of the American Meteorological Society (81) S1-S50.


The Saffir-Simpson Scale for Tropical Cyclones

Category Miles Per Hour (mph) Knots (kt) Kilometers Per Hour (km hr-1)
Tropical Storm
 39-73 34-63 63-118
Cat 1
 74-95 64-82 119-153
Cat 2
 96-110 83-95 154-177
Cat 3
 111-130 96-113 178-209
Cat 4
 131-155 114-135 210-249
Cat 5
 155 135 249



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