2004 North Atlantic Ocean Tropical Cyclones

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) Landfall Information (date, location and sustained winds)
Alex 7/31/04 8/5/04 Cat 3 105 130 11.1675 x 104
Bonnie 8/9/04 8/12/04 TS 55 65 2.4975 x 104
Charley 8/9/04 8/15/04 Cat 4 125 150 10.4375 x 104 8/14/04–8/16/04 Total Precip (map)
Danielle 8/13/04 8/21/04 Cat 2 90 110 11.95 x 104
Earl 8/13/04 8/16/04 TS 40 50 1.045 x 104
Frances 8/25/04 9/7/04 Cat 4 125 155 46.7975 x 104 8/14/04–8/16/04 Total Precip (map)
Gaston 8/27/04 9/1/04 TS 60 75 2.175 x 104
Hermine 8/29/04 8/31/04 TS 45 55 1.0125 x 104
Ivan 9/3/04
9/22/04
9/17/04
9/24/04
Cat 5 145 175 69.95 x 104 9/15/04–9/19/04 Total Precip (map)
Jeanne 9/14/04 9/27/04 Cat 3 100 120 24.8921 x 104 9/25/04–9/29/04 Total Precip (map)>
Karl 9/17/04 9/24/04 Cat 4 120 145 27.99 x 104
Lisa 9/20/04 10/3/04 Cat 1 65 80 11.9925 x 104
Matthew 10/8/04 10/10/04 TS 40 50 0.7725 x 104
Nicole 10/10/04 10/11/04 Sub-TS 45 55 1.1625 x 104
Otto 11/30/04 12/2/04 TS 45 55 1.05 x 104
*The (ACE) Index calculations are based on preliminary data.

2004 Total North Atlantic Ocean ACE Index = 224.8921 x 104 kt2

*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 (sustained winds of 34 kt or greater). Note that the official NOAA definition of the ACE Index does not include those periods when the system is characterized as sub-tropical. However, we are including this information to allow for comparison between individual cyclones across all basins, many of which contain records which inadequately distinguish between tropical and subtropical cyclones. For a complete description of the ACE Index see Bell and Chelliah (2006), Journal of Climate (19) 590-612.


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