Talk:2009 Atlantic hurricane season/ACE calcs

This is the page for calculating the Accumulated Cyclone Energy for the 2009 Atlantic hurricane season.

The ACE is calculated by summing the squares of the estimated maximum sustained velocity of every active tropical storm (wind speed 35 knots or higher), at six-hour intervals. The numbers are usually divided by 10,000 to make them more manageable. The unit of ACE is 10⁴ kt², and for use as an index the unit is assumed. If any storms of a season happen to cross years, the storm's ACE counts for the previous year.

$\sum _{}^{}{\frac {{v_{\mathrm {max} }}^{2}}{10^{4}}},$

where v_max is estimated sustained wind speed in knots.

Operational (Advisories)

01L.NONAME

• Never strengthened into a tropical storm, ACE is zero

02L.Ana

• From 5 pm AST on August 13 to 12:30 am AST on August 15, the system was a low, not a tropical cyclone.

Adv.	Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
1	11 August	6 am AST	25	Special
2	11 August	11 am AST	25	0
3	11 August	5 pm AST	25	0
4	11 August	11 pm AST	30	0
5	12 August	5 am AST	30	0
6	12 August	11 am AST	30	0
7	12 August	5 pm AST	30	0
8	12 August	11 pm AST	30	0
9	13 August	5 am AST	25	0
10	13 August	11 am AST	25	0
11	13 August	5 pm AST	25	Low
12	15 August	12:30 am AST	30	Special
13	15 August	5 am AST	35	0.1225
14	15 August	11 am AST	35	0.1225
15	15 August	5 pm AST	35	0.1225
16	15 August	11 pm AST	35	0.1225
17	16 August	5 am AST	35	0.1225
18	16 August	11 am AST	35	0.1225
19	16 August	5 pm AST	30	0
20	16 August	11 pm AST	30	0
21	17 August	5 am AST	30	0
22	17 August	11 am AST	30	0
23	17 August	5 pm AST	30	Low
Total				0.7350

03L.Bill

Adv.	Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
1	15 August	11 am AST	30	0
2	15 August	5 pm AST	35	0.1225
3	15 August	11 pm AST	35	0.1225
4	16 August	5 am AST	40	0.1600
5	16 August	11 am AST	50	0.2500
6	16 August	5 pm AST	55	0.3025
7	16 August	11 pm AST	60	0.3600
8	17 August	5 am AST	65	0.4225
9	17 August	11 am AST	80	0.6400
10	17 August	5 pm AST	80	0.6400
11	17 August	11 pm AST	85	0.7225
12	18 August	5 am AST	85	0.7225
13	18 August	11 am AST	90	0.8100
14	18 August	5 pm AST	95	0.9025
15	18 August	11 pm AST	110	1.2100
16	19 August	5 am AST	115	1.3225
17	19 August	11 am AST	115	1.3225
18	19 August	5 pm AST	115	1.3225
19	19 August	11 pm AST	115	1.3225
20	20 August	5 am AST	110	1.2100
21	20 August	11 am AST	105	1.1025
22	20 August	5 pm AST	110	1.2100
23	20 August	11 pm AST	110	1.2100
24	21 August	5 am AST	105	1.1025
25	21 August	11 am AST	100	1.0000
26	21 August	5 pm AST	90	0.8100
27	21 August	11 pm AST	90	0.8100
28	22 August	5 am AST	90	0.8100
29	22 August	11 am AST	85	0.7225
30	22 August	5 pm AST	75	0.5625
31	22 August	11 pm AST	75	0.5625
32	23 August	5 am AST	75	0.5625
33	23 August	11 am AST	75	0.5625
34	23 August	5 pm AST	65	0.4225
35	23 August	11 pm AST	65	0.4225
36	24 August	5 am AST	60	EXT
Total				25.7600

04L.Claudette

Adv.	Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
1	16 August	5 am EDT	30	0
2	16 August	11 am EDT	30	0
3	16 August	2 pm EDT	45	Special
4	16 August	5 pm EDT	45	0.2025
5	16 August	10 pm CDT	45	0.2025
6	17 August	4 am CDT	35	0.1225
7	17 August	10 am CDT	30	0
8	17 August	4 pm CDT	25	0
9	17 August	10 pm CDT	-	Low
Total				0.5275

05L.Danny

Adv.	Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
1	26 August	11 am EDT	40	0.1600
2	26 August	5 pm EDT	40	0.1600
3	26 August	11 pm EDT	45	0.2025
4	27 August	5 am EDT	50	0.2500
5	27 August	11 am EDT	50	0.2500
6	27 August	5 pm EDT	45	0.2025
7	27 August	11 pm EDT	40	0.1600
8	28 August	5 am EDT	35	0.1225
9	28 August	11 am EDT	35	0.1225
10	28 August	5 pm EDT	35	0.1225
11	28 August	11 pm EDT	35	0.1225
12	29 August	5 am EDT	30	Low
Total				1.8750

06L.Erika

Adv.	Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
1	1 September	5 pm EDT	45	0.2025
2	1 September	11 pm AST	50	0.2500
3	2 September	5 am AST	45	0.2025
4	2 September	11 am AST	35	0.1225
5	2 September	5 pm AST	35	0.1225
6	2 September	11 pm AST	35	0.1225
7	3 September	5 am AST	35	0.1225
8	3 September	11 am AST	35	0.1225
9	3 September	5 pm AST	30	0
10	3 September	11 pm AST	25	Low
Total				1.2675

07L.Fred

Adv.	Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
1	7 September	5 pm AST	30	0
2	7 September	11 pm AST	35	0.1225
3	8 September	5 am AST	45	0.2025
4	8 September	11 am AST	55	0.3025
5	8 September	5 pm AST	60	0.3600
6	8 September	11 pm AST	65	0.4225
7	9 September	5 am AST	90	0.8100
8	9 September	11 am AST	105	1.1025
9	9 September	5 pm AST	100	1.0000
10	9 September	11 pm AST	90	0.8100
11	10 September	5 am AST	90	0.8100
12	10 September	11 am AST	85	0.7225
13	10 September	5 pm AST	80	0.6400
14	10 September	11 pm AST	75	0.5625
15	11 September	5 am AST	75	0.5625
16	11 September	11 am AST	70	0.4900
17	11 September	5 pm AST	60	0.3600
18	11 September	11 pm AST	50	0.2500
19	12 September	5 am AST	40	0.1600
20	12 September	11 am AST	35	0.1225
21	12 September	5 pm AST	30	Low
Total				9.8125

08L.NONAME

• Never strengthened into a tropical storm, ACE is zero

09L.Grace

Adv.	Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
1	4 October	11 pm AST	55	0.3025
2	5 October	5 am AST	60	0.3600
3	5 October	11 am AST	55	0.3025
4	5 October	5 pm AST	50	0.2500
5	5 October	11 pm AST	45	Absorbed
Total				1.2150

10L.Henri

Adv.	Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
1	6 October	5 pm AST	35	0.1225
2	6 October	11 pm AST	40	0.1600
3	7 October	5 am AST	45	0.2025
4	7 October	11 am AST	40	0.1600
5	7 October	5 pm AST	35	0.1225
6	7 October	11 pm AST	30	0
7	8 October	5 am AST	30	0
8	8 October	11 am AST	30	0
9	8 October	5 pm AST	25	Low
Total				0.7675

11L.Ida

Adv.	Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
1	4 November	10 am EST	30	0
2	4 November	4 pm EST	50	0.2500
3	4 November	10 pm EST	55	0.3025
4	5 November	4 am EST	60	0.3600
5	5 November	10 am EST	65	0.4225
6	5 November	4 pm EST	50	0.2500
7	5 November	10 pm EST	30	0
8	6 November	4 am EST	30	0
9	6 November	10 am EST	30	0
10	6 November	4 pm EST	30	0
11	6 November	10 pm EST	30	0
12	7 November	4 am EST	40	0.1600
13	7 November	10 am EST	50	0.2500
14	7 November	4 pm EST	60	0.3600
15	7 November	10 pm EST	60	0.3600
16	8 November	1:15 am CST	80	Special
17	8 November	3 am CST	80	0.6400
18	8 November	9 am CST	80	0.6400
19	8 November	12 pm CST	85	Special
20	8 November	3 pm CST	85	0.7225
21	8 November	9 pm CST	90	0.8100
22	9 November	3 am CST	80	0.6400
23	9 November	9 am CST	60	0.3600
24	9 November	3 pm CST	60	0.3600
25	9 November	9 pm CST	55	0.3025
26	10 November	3 am CST	45	0.2025
27	10 November	9 am CST	30	EXT
Total				7.3925

Best Track (TCR)

01L.NONAME

• Tropical Cyclone Report
• Never strengthened into a tropical storm, ACE is zero

02L.Ana

• Tropical Cyclone Report

Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
11 Aug	0600 UTC	25	0.0000
11 Aug	1200 UTC	25	0.0000
11 Aug	1800 UTC	25	0.0000
12 Aug	0000 UTC	30	0.0000
12 Aug	0600 UTC	30	0.0000
12 Aug	1200 UTC	35	0.1225
12 Aug	1800 UTC	35	0.1225
From 0000 UTC on August 13 to 0000 UTC on August 15, the system was a low, not a tropical cyclone.
15 Aug	0600 UTC	35	0.1225
15 Aug	1200 UTC	35	0.1225
15 Aug	1800 UTC	35	0.1225
16 Aug	0000 UTC	35	0.1225
16 Aug	0600 UTC	35	0.1225
Total			0.8575

03L.Bill

• Tropical Cyclone Report

Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
15 Aug	0600 UTC	30	0.0000
15 Aug	1200 UTC	30	0.0000
15 Aug	1800 UTC	35	0.1225
16 Aug	0000 UTC	35	0.1225
16 Aug	0600 UTC	40	0.1600
16 Aug	1200 UTC	50	0.2500
16 Aug	1800 UTC	55	0.3025
17 Aug	0000 UTC	60	0.3600
17 Aug	0600 UTC	65	0.4225
17 Aug	1200 UTC	75	0.5625
17 Aug	1800 UTC	80	0.6400
18 Aug	0000 UTC	85	0.7225
18 Aug	0600 UTC	90	0.8100
18 Aug	1200 UTC	95	0.9025
18 Aug	1800 UTC	100	1.0000
19 Aug	0000 UTC	105	1.1025
19 Aug	0600 UTC	115	1.3225
19 Aug	1200 UTC	115	1.3225
19 Aug	1800 UTC	115	1.3225
20 Aug	0000 UTC	115	1.3225
20 Aug	0600 UTC	115	1.3225
20 Aug	1200 UTC	105	1.1025
20 Aug	1800 UTC	110	1.2100
21 Aug	0000 UTC	110	1.2100
21 Aug	0600 UTC	105	1.1025
21 Aug	1200 UTC	100	1.0000
21 Aug	1800 UTC	95	0.9025
22 Aug	0000 UTC	90	0.8100
22 Aug	0600 UTC	90	0.8100
22 Aug	1200 UTC	85	0.7225
22 Aug	1800 UTC	80	0.6400
23 Aug	0000 UTC	80	0.6400
23 Aug	0600 UTC	75	0.5625
23 Aug	1200 UTC	70	0.4900
23 Aug	1800 UTC	65	0.4225
24 Aug	0000 UTC	65	0.4225
24 Aug	0600 UTC	60	0.3600
24 Aug	1200 UTC	60	EXT
Total			26.5000

04L.Claudette

• Tropical Cyclone Report

Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
16 Aug	0600 UTC	30	0.0000
16 Aug	1200 UTC	35	0.1225
16 Aug	1800 UTC	50	0.2500
17 Aug	0000 UTC	45	0.2025
17 Aug	0600 UTC	40	0.1600
17 Aug	1200 UTC	25	0.0000
17 Aug	1800 UTC	20	0.0000
18 Aug	0000 UTC	--	dissipated
Total			0.7350

05L.Danny

• Tropical Cyclone Report

Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
26 Aug	1200 UTC	40	0.1600
26 Aug	1800 UTC	45	0.2025
27 Aug	0000 UTC	50	0.2500
27 Aug	0600 UTC	50	0.2500
27 Aug	1200 UTC	50	0.2500
27 Aug	1800 UTC	45	0.2025
28 Aug	0000 UTC	40	0.1600
28 Aug	0600 UTC	35	0.1225
28 Aug	1200 UTC	35	0.1225
28 Aug	1800 UTC	35	0.1225
29 Aug	0000 UTC	35	0.1225
29 Aug	0600 UTC	--	absorbed
Total			1.9650

06L.Erika

• Tropical Cyclone Report

Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
01 Sep	1800 UTC	45	0.2025
02 Sep	0000 UTC	45	0.2025
02 Sep	0600 UTC	45	0.2025
02 Sep	1200 UTC	35	0.1225
02 Sep	1800 UTC	35	0.1225
03 Sep	0000 UTC	35	0.1225
03 Sep	0600 UTC	40	0.1600
03 Sep	1200 UTC	40	0.1600
03 Sep	1800 UTC	30	0.0000
04 Sep	0000 UTC	25	Low
Total			1.2950

07L.Fred

• Tropical Cyclone Report

Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
07 Sep	1800 UTC	30	0.0000
08 Sep	0000 UTC	35	0.1225
08 Sep	0600 UTC	45	0.2025
08 Sep	1200 UTC	55	0.3025
08 Sep	1800 UTC	60	0.3600
09 Sep	0000 UTC	70	0.4900
09 Sep	0600 UTC	90	0.8100
09 Sep	1200 UTC	105	1.1025
09 Sep	1800 UTC	100	1.0000
10 Sep	0000 UTC	95	0.9025
10 Sep	0600 UTC	90	0.8100
10 Sep	1200 UTC	85	0.7225
10 Sep	1800 UTC	80	0.6400
11 Sep	0000 UTC	80	0.6400
11 Sep	0600 UTC	75	0.5625
11 Sep	1200 UTC	65	0.4225
11 Sep	1800 UTC	55	0.3025
12 Sep	0000 UTC	50	0.2500
12 Sep	0600 UTC	40	0.1600
12 Sep	1200 UTC	35	0.1225
12 Sep	1800 UTC	30	Low
Total			9.9250

08L.NONAME

• Tropical Cyclone Report
• Never strengthened into a tropical storm, ACE is zero

09L.Grace

• Tropical Cyclone Report

Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
04 Oct	0600 UTC	40	0.1600
04 Oct	1200 UTC	45	0.2025
04 Oct	1800 UTC	50	0.2500
05 Oct	0000 UTC	55	0.3025
05 Oct	0600 UTC	55	0.3025
05 Oct	1200 UTC	55	0.3025
05 Oct	1800 UTC	50	0.2500
06 Oct	0000 UTC	45	0.2025
06 Oct	0600 UTC	40	EXTRA
Total			1.9725

10L.Henri

• Tropical Cyclone Report

Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
06 Oct	0000 UTC	30	0.0000
06 Oct	0600 UTC	35	0.1225
06 Oct	1200 UTC	35	0.1225
06 Oct	1800 UTC	35	0.1225
07 Oct	0000 UTC	40	0.1600
07 Oct	0600 UTC	45	0.2025
07 Oct	1200 UTC	45	0.2025
07 Oct	1800 UTC	40	0.1600
08 Oct	0000 UTC	35	0.1225
08 Oct	0600 UTC	30	0.0000
08 Oct	1200 UTC	30	0.0000
08 Oct	1800 UTC	25	0.0000
Total			1.2150

11L.Ida

• Tropical Cyclone Report

Date	Time	Maximum Sustained Winds (kt)	ACE (104 kt2)
04 Nov	0600 UTC	30	0.0000
04 Nov	1200 UTC	35	0.1225
04 Nov	1800 UTC	45	0.2025
05 Nov	0000 UTC	55	0.3025
05 Nov	0600 UTC	65	0.4225
05 Nov	1200 UTC	70	0.4900
05 Nov	1800 UTC	50	0.2500
06 Nov	0000 UTC	35	0.1225
06 Nov	0600 UTC	30	0.0000
06 Nov	1200 UTC	30	0.0000
06 Nov	1800 UTC	30	0.0000
07 Nov	0000 UTC	30	0.0000
07 Nov	0600 UTC	35	0.1225
07 Nov	1200 UTC	55	0.3025
07 Nov	1800 UTC	60	0.3600
08 Nov	0000 UTC	70	0.4900
08 Nov	0600 UTC	80	0.6400
08 Nov	1200 UTC	85	0.7225
08 Nov	1800 UTC	85	0.7225
09 Nov	0000 UTC	90	0.8100
09 Nov	0600 UTC	80	0.6400
09 Nov	1200 UTC	60	0.3600
09 Nov	1800 UTC	65	0.4225
10 Nov	0000 UTC	60	0.3600
10 Nov	0600 UTC	50	0.2500
10 Nov	1200 UTC	35	extratropical
Total			8.115

Season total

Storm	Type	ACE (104 kt2)
01L (NONAME)	Best Track	0.0000
02L (Ana)	Best Track	0.8575
03L (Bill)	Best Track	26.5000
04L (Claudette)	Best Track	0.7350
05L (Danny)	Best Track	1.9650
06L (Erika)	Best Track	1.2950
07L (Fred)	Best Track	9.9250
08L (NONAME)	Best Track	0.0000
09L (Grace)	Best Track	1.9725
10L (Henri)	Best Track	1.2150
11L (Ida)	Best Track	8.1150
Total		52.58

See also

• Pacific ACE calcs