2008-2009 Australian Basin Tropical Cyclones (90°E -160°E)

Tropical Cyclone Cyclogenesis Date Cyclolysis Date Australian Category (max gusts) Maximum Gust (km/h) Saffir-Simpson Category (sustained winds) Maximum 6-hr Sustained Wind (kt) Maximum 6-hr Wind Gust (kt) Estimated Accumulated Cyclone Energy (ACE*) Index (kt2) Landfall Information (date, location and sustained winds)
Anika 11/18/08 11/20/08 Cat 1 120 TS 50 65 1.6706 x 104
Billy 12/19/08 12/27/08 Cat 4 241 Cat 1 105 130 12.2619 x 104
Charlotte 01/11/09 01/11/09 Cat 1 83 TS 35 45 .3675 x 104 01/11/09 - near Mornington Island, Australia (35 kt)
Dominic 01/26/09 01/27/09 Cat 1 120 TS 50 65 .7350 x 104 01/27/09 - East-Northeast of Learmonth, Australia (50 kt)
Freddy 02/07/09 02/09/09 Cat 2 130 TS 55 70 2.2344 x 104
Gabrielle 03/02/09 03/04/09 Cat 1 83 TS 35 45 1.1025 x 10
Hamish 03/06/09 03/11/09 Cat 5 296 Cat 4 130 160 21.3794 x 10
Ilsa 03/18/09 03/23/09 Cat 4 232 Cat 3 100 125 10.9619 x 10
*The (ACE) Index calculations are based on preliminary data.


*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 Australian Scale for Tropical Cyclones

         Note: based on estimates or observations of the strongest wind gust.
Category Kilometers Per Hour (km/h) Knots (kt) Miles Per Hour (mph)
Cat 1
125 or less 67 or less 78 or less
Cat 2
125-169 67-91 78-105
Cat 3
170-224 92-121 106-139
Cat 4
225-279 121-151 140-173
Cat 5
280 or greater 151 or greater 174 or greater


The Saffir-Simpson Scale for Tropical Cyclones


Category Miles Per Hour (mph) Knots (kt) Kilometers Per Hour (km hr-1)
Tropical Storm (TS)
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
156 or greater 136 or greater 250 or greater