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Subject: E11) How many tropical cyclones have there been each year in the Atlantic basin? What years were the greatest and fewest seen?

Contributed by Chris Landsea

The Atlantic hurricane database (or HURDAT) extends back to 1851. However, because tropical storms and hurricane spend much of their lifetime over the open ocean - some never hitting land - many systems were "missed" during the late 19th and early 20th Centuries (Vecchi and Knutson 2008). Starting in 1944, systematic aircraft reconnaissance was commenced for monitoring both tropical cyclones and disturbances that had the potential to develop into tropical storms and hurricanes. This did provide much improved monitoring, but still about half of the Atlantic basin was not covered (Sheets 1990). Beginning in 1966, daily satellite imagery became available at the National Hurricane Center, and thus statistics from this time forward are most complete (McAdie et al. 2009).

For hurricanes striking the USA Atlantic and Gulf coasts, one can go back further in time with relatively reliable counts of systems because enough people have lived along coastlines since 1900.

Thus, the following records for the period of reliable data hold for the entire Atlantic basin (from 1966-2011) and for the USA coastline (1900-2011):

Category Average Maximum Years Minimum Years
Named storms
(including subtropical storms)
11.7& 282005 41983
Hurricanes 6.2 152005 21982
Major Hurricanes 2.4 72005* 0many times, last 1994
USA landfalling hurricanes 1.7 61916, 1985, 2004+ 0many, last 2010
USA landfalling major hurricanes 0.6 42005 0many, last 2011

& Landsea et al. (2010) documented a rather large increase in short-lived tropical storms and hurricanes in the last decade, which is likely due to improved monitoring capabilities, that may be influencing the climatological average number of TCs in the Atlantic basin. With the artificial jump in the 2000s in the frequency of short-lived systems, a more realistic estimate of the long-term climatology may be closer to 13 tropical storms and hurricanes per year.
* 1950 is recorded as the busiest season in the whole database for number of Major Hurricanes with 8.
+ 1886 is recorded as the most active hurricane season for the continental USA with 7 landfalling hurricanes.

Atlantic basin
Individual years with the numbers in each category

Year Named
Storms
Hurricanes Major
Hurricanes
ACE
^ Click header for diagram ^
185163136
185255173
185384276
185453131
185554118
185664249
185743043
185866045
185987161
186076162
186186050
186263046
186395050
186453027
186573049
186677188
186797160
186843035
1869107151
18701110288
187186288
187254065
187353269
187474047
187565172
187654257
187783173
187812102181
187986264
18801192131
188174059
188265263
188343267
188444172
188586158
188612104166
188719112182
188896285
1889960104
189042133
18911071116
1892950116
189312105231
1894754135
189562069
1896762136
189763055
18981151113
1899952150
190073284
1901125093
190253033
19031071102
190453025
190551128
19061163163
190750013
1908106195
1909116492
191053164
191163035
191274156
191364036
19141003
1915653127
191615105144
191742261
191864140
191952155
192054030
192175287
192253155
192394149
19241152100
19254208
19261186230
192784156
192864183
192953148
193032250
193192139
19321164136
193321105213
1934116060
193565395
19361671108
193793061
193883173
193953134
194084052
194164261
1942104166
1943105294
1944117396
1945115367
194663122
1947952112
1948964106
1949137398
195013118243
19511085137
195276387
19531464104
19541182113
19551296199
195684254
195783284
19581075121
1959117277
196074288
19611187205
196253136
1963972118
19641266170
196564184
19661173145
1967861122
196884035
196918125158
1970105234
1971136197
197273028
197384143
1974114261
197596373
1976106281
197765125
1978125262
197995291
19801192147
1981127393
198262129
198343117
1984135171
1985117388
198664036
198773134
19881253103
19891172135
1990148191
199184234
199274175
199384139
199473032
199519115227
19961396166
199783140
199814103182
19991285177
20001583116
20011594106
2002124266
20031673175
20041596224
200528157248
2006105278
2007156272
20081685144
200993251
201019125165
20111973121
Average
1968-2011
11.76.22.494.8

Named Storms = Tropical Storms, Hurricanes and Subtropical Storms
Hurricanes = Saffir-Simpson Hurricane Scale 1 to 5
Major Hurricanes = Saffir-Simpson Hurricane Scale 3, 4, or 5
"ACE" = Accumilated Cyclone Energy - An index that combines the numbers of systems, how long they existed and how intense they became. It is calculated by squaring the maximum sustained surface wind in the system every six hours and summing it up for the season. It is expressed in 104 kt2.

References:

Landsea,C.W., G.A. Vecchi, L. Bengtsson, and T. R. Knutson, 2010: Impact of Duration Thresholds on Atlantic Tropical Cyclone Counts. Journal of Climate, 23, 2508-2519. (in press).

McAdie, C. J., C. W. Landsea, C. J. Neuman, J. E. David, E. Blake, and G. R. Hamner, 2009: Tropical Cyclones of the North Atlantic Ocean, 1851-2006. Historical Climatology Series 6-2,Prepared by the National Climatic Data Center, Asheville, NC in cooperation with the National Hurricane Center, Miami, FL, 238 pp.

Sheets, R.C., 1990: "The National Hurricane Center - Past, present, and future.", Wea. Forecasting,5, 185-232.

Vecchi, G.A. and T. R. Knutson, 2008. "On estimates of historical North Atlantic tropical cyclone activity.", J. Climate, 21, 3580.

Last Revised : February 10, 2012

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