ACE Per A Storm/Percentage Form To Hurricane/Major Hurricane

[Ptarmigan]

Some seasons like 2004 and 2005 have really ACE. However, the number of storms that formed are different from each other. 2004 had 15/9/6, while 2005 had 28/15/7. Each of them, they had one sub-tropical storm, in which the ACE is not counted. Now, it raises, is it the quantity or quality of the storm, quality in the number of hurricanes and major hurricanes forming. Some seasons have really high ACEs despite having average or below or above average number of storms forming, like 1950, 1961, 1998 and 1999. There are other seasons with lower ACEs, but have many storms forming like 1936 and 2007.

Here is a list of seasons and their ACE from 1870 to 2009 and ACE per a storm.

Code: Select all

1870	11	10	2	88	8	0.909091	0.181818
1871	8	6	2	88	11	0.75	0.25
1872	5	4	0	65	13	0.8	0
1873	5	3	2	69	13.8	0.6	0.4
1874	7	4	0	47	6.714286	0.571429	0
1875	6	5	1	72	12	0.833333	0.166667
1876	5	4	2	57	11.4	0.8	0.4
1877	8	3	1	73	9.125	0.375	0.125
1878	12	10	2	181	15.083333	0.833333	0.166667
1879	8	6	2	64	8	0.75	0.25
1880	11	9	2	131	11.909091	0.818182	0.181818
1881	7	4	0	59	8.428571	0.571429	0
1882	6	5	2	63	10.5	0.833333	0.333333
1883	4	3	2	67	16.75	0.75	0.5
1884	4	4	1	72	18	1	0.25
1885	8	6	1	58	7.25	0.75	0.125
1886	12	10	4	166	13.833333	0.833333	0.333333
1887	19	11	2	182	9.578947	0.578947	0.105263
1888	9	6	2	85	9.444444	0.666667	0.222222
1889	9	6	0	104	11.555556	0.666667	0
1890	4	2	1	33	8.25	0.5	0.25
1891	10	7	1	116	11.6	0.7	0.1
1892	9	5	0	116	12.888889	0.555556	0
1893	12	10	5	231	19.25	0.833333	0.416667
1894	7	5	4	135	19.285714	0.714286	0.571429
1895	6	2	0	69	11.5	0.333333	0
1896	7	6	2	136	19.428571	0.857143	0.285714
1897	6	3	0	55	9.166667	0.5	0
1898	11	5	1	113	10.272727	0.454545	0.090909
1899	9	5	2	150	16.666667	0.555556	0.222222
1900	7	3	2	84	12	0.428571	0.285714
1901	12	5	0	93	7.75	0.416667	0
1902	5	3	0	33	6.6	0.6	0
1903	10	7	1	102	10.2	0.7	0.1
1904	5	3	0	25	5	0.6	0
1905	5	1	1	28	5.6	0.2	0.2
1906	11	6	3	163	14.818182	0.545455	0.272727
1907	5	0	0	13	2.6	0	0
1908	10	6	1	95	9.5	0.6	0.1
1909	11	6	4	92	8.363636	0.545455	0.363636
1910	5	3	1	64	12.8	0.6	0.2
1911	6	3	0	35	5.833333	0.5	0
1912	7	4	1	56	8	0.571429	0.142857
1913	6	4	0	36	6	0.666667	0
1914	1	0	0	3	3	0	0
1915	6	5	3	127	21.166667	0.833333	0.5
1916	15	10	5	144	9.6	0.666667	0.333333
1917	4	2	2	61	15.25	0.5	0.5
1918	6	4	1	40	6.666667	0.666667	0.166667
1919	5	2	1	55	11	0.4	0.2
1920	5	4	0	30	6	0.8	0
1921	7	5	2	87	12.428571	0.714286	0.285714
1922	5	3	1	55	11	0.6	0.2
1923	9	4	1	49	5.444444	0.444444	0.111111
1924	11	5	2	100	9.090909	0.454545	0.181818
1925	4	2	0	7	1.75	0.5	0
1926	11	8	6	222	20.181818	0.727273	0.545455
1927	7	4	2	56	8	0.571429	0.285714
1928	6	4	1	75	12.5	0.666667	0.166667
1929	3	3	1	43	14.333333	1	0.333333
1930	2	2	1	39	19.5	1	0.5
1931	9	2	1	39	4.333333	0.222222	0.111111
1932	11	6	4	136	12.363636	0.545455	0.363636
1933	21	10	5	213	10.142857	0.47619	0.238095
1934	11	6	0	60	5.454545	0.545455	0
1935	6	5	3	95	15.833333	0.833333	0.5
1936	16	7	1	108	6.75	0.4375	0.0625
1937	9	3	0	61	6.777778	0.333333	0
1938	8	3	1	73	9.125	0.375	0.125
1939	5	3	1	34	6.8	0.6	0.2
1940	8	4	0	52	6.5	0.5	0
1941	6	4	2	61	10.166667	0.666667	0.333333
1942	10	4	1	66	6.6	0.4	0.1
1943	10	5	2	94	9.4	0.5	0.2
1944	11	7	3	96	8.727273	0.636364	0.272727
1945	11	5	3	67	6.090909	0.454545	0.272727
1946	6	3	1	22	3.666667	0.5	0.166667
1947	9	5	2	112	12.444444	0.555556	0.222222
1948	9	6	4	106	11.777778	0.666667	0.444444
1949	13	7	3	98	7.538462	0.538462	0.230769
1950	13	11	8	243	18.692308	0.846154	0.615385
1951	10	8	5	137	13.7	0.8	0.5
1952	7	6	3	87	12.428571	0.857143	0.428571
1953	14	6	4	104	7.428571	0.428571	0.285714
1954	11	8	2	113	10.272727	0.727273	0.181818
1955	12	9	6	199	16.583333	0.75	0.5
1956	8	4	2	54	6.75	0.5	0.25
1957	8	3	2	84	10.5	0.375	0.25
1958	10	7	5	121	12.1	0.7	0.5
1959	11	7	2	77	7	0.636364	0.181818
1960	7	4	2	88	12.571429	0.571429	0.285714
1961	11	8	7	205	18.636364	0.727273	0.636364
1962	5	3	1	36	7.2	0.6	0.2
1963	9	7	2	118	13.111111	0.777778	0.222222
1964	12	6	6	170	14.166667	0.5	0.5
1965	6	4	1	84	14	0.666667	0.166667
1966	11	7	3	145	13.181818	0.636364	0.272727
1967	8	6	1	122	15.25	0.75	0.125
1968	8	4	0	35	4.375	0.5	0
1969	18	12	5	158	8.777778	0.666667	0.277778
1970	10	5	2	34	3.4	0.5	0.2
1971	13	6	1	97	7.461538	0.461538	0.076923
1972	7	3	0	28	4	0.428571	0
1973	8	4	1	43	5.375	0.5	0.125
1974	11	4	2	61	5.545455	0.363636	0.181818
1975	9	6	3	73	8.111111	0.666667	0.333333
1976	10	6	2	81	8.1	0.6	0.2
1977	6	5	1	25	4.166667	0.833333	0.166667
1978	12	5	2	62	5.166667	0.416667	0.166667
1979	9	5	2	91	10.111111	0.555556	0.222222
1980	11	9	2	147	13.363636	0.818182	0.181818
1981	12	7	3	93	7.75	0.583333	0.25
1982	6	2	1	29	4.833333	0.333333	0.166667
1983	4	3	1	17	4.25	0.75	0.25
1984	13	5	1	71	5.461538	0.384615	0.076923
1985	11	7	3	88	8	0.636364	0.272727
1986	6	4	0	36	6	0.666667	0
1987	7	3	1	34	4.857143	0.428571	0.142857
1988	12	5	3	103	8.583333	0.416667	0.25
1989	11	7	2	135	12.272727	0.636364	0.181818
1990	14	8	1	91	6.5	0.571429	0.071429
1991	8	4	2	34	4.25	0.5	0.25
1992	7	4	1	75	10.714286	0.571429	0.142857
1993	8	4	1	39	4.875	0.5	0.125
1994	7	3	0	32	4.571429	0.428571	0
1995	19	11	5	227	11.947368	0.578947	0.263158
1996	13	9	6	166	12.769231	0.692308	0.461538
1997	8	3	1	40	5	0.375	0.125
1998	14	10	3	182	13	0.714286	0.214286
1999	12	8	5	177	14.75	0.666667	0.416667
2000	15	8	3	116	7.733333	0.533333	0.2
2001	15	9	4	106	7.066667	0.6	0.266667
2002	12	4	2	66	5.5	0.333333	0.166667
2003	16	7	3	175	10.9375	0.4375	0.1875
2004	15	9	6	224	14.933333	0.6	0.4
2005	28	15	7	248	8.857143	0.535714	0.25
2006	10	5	2	78	7.8	0.5	0.2
2007	15	6	2	72	4.8	0.4	0.133333
2008	16	8	5	144	9	0.5	0.3125
2009	9	3	2	51	5.666667	0.333333	0.222222

Source
http://www.aoml.noaa.gov/hrd/tcfaq/E11.html

Sorry for any formatting error. Here is how the list is organized.
Year Number of Storms Forming Hurricanes Major Hurricanes ACE ACE Per A Storm Percentage Form To Hurricane Percentage Form To Major Hurricane

ACE Per A Storm Statistics
Average
9.78

Median
9.125

Standard Deviation
4.232329

Least
1.75 (1925)

Most
21.166667 (1915)

5th Percentile
4.245833

25th Percentile
6.6

50th Percentile
9.125

75th Percentile
12.458333

95th Percentile
18.639161

Seasons with below, average, or slightly above average storms forming that had high ACEs had many hurricanes and major hurricanes form, like we see in 1950, 1961, and 1999. This leads to the percentage of how many hurricanes and major hurricanes form per a season.

Percentage of Hurricanes Forming
Average
0.588353

Median
0.578947

Standard Deviation
0.174957

5th Percentile
0.333333

25th Percentile
0.5

50th Percentile
0.578947

75th Percentile
0.703571

95th Percentile
0.833974

Least
0 (1907, 1914)

Most
1 (1884, 1929, and 1930)


Percentage of Major Hurricanes Forming
Average
0.214143

Median
0.2

Standard Deviation
0.152141

5th Percentile
0

25th Percentile
0.121528

50th Percentile
0.2

75th Percentile
0.285714

95th Percentile
0.5

Least
0 (Many, most recent is 1994)

Most
0.636364 (1961)

Please keep in mind that any hurricane data before 1950s should be treated as dubious because there were no satellites back then.

What does it mean? Quantity is not everything. 2007 had 15 storms form, yet the ACE was 72, which is 4.8 per a storm right there. 1961 had 11 storms form and had an ACE of 205, 18.6 ACE per a storm. Same goes with 1998, 1999, and 2004. 2005 had 28 storms form, yet had an 8.8 ACE per a storm.

Also, some of the most active season in terms of ACE had many long tracking hurricanes from the Cape Verde Islands. Also, they had many hurricanes and major hurricanes form. Also, percentage of hurricanes and major hurricanes is higher, like in 1961, 1998, 1999, and 2004.

[sleetstorm]

What does the acronym, "ACE", stand for, Ptarmigan?

[Ptarmigan]

Accumulated Cyclone Energy.

Related to the square of the max winds, added up each six hours.


ACE counts 6 hours of any 100 mph hurricane the same. One might have tropical storm winds extending out hundreds of miles, the other is a tightly wound up little storm.

After Ike, I heard a preference by some for IKE, which makes sense, somehow...

http://www.aoml.noaa.gov/hrd/ike/Files/ ... inal-1.pdf

Good point. I think IKE is better. The formula is complex though.