Table 1. The frequency of surge durations. The first column is the number of consecutive days (duration) that the northeast surge index ³ 10 m s^-1 at least once during each day of the duration. The second column is the total number of events associated with the duration. The third column is the cumulative number of events that lasted for at least the duration, and the fourth column is the maximum value of surge index among surges of the duration.
	Surge duration	Number of events	Cumul-ative no. events	Max surge index	Surge duration ´ number of events for duration ³ 7 days	Surge duration ´ number of events for duration ³ 5 days
	1	151	449	13.0
	2	87	298	13.6
	3	62	211	14.3
	4	40	149	15.3
	5	27	109	15.0		135
	6	21	82	15.8		126
	7	11	61	14.2	77	77
	8	13	50	16.5	104	104
	9	15	37	15.1	135	135
	10	6	22	15.4	60	60
	11	6	16	15.1	66	66
	12	4	10	16.0	48	48
	13	2	6	15.2	26	26
	14	1	4	14.3	14	14
	15	0	3	0	0	0
	16	1	3	14.6	16	16
	17	1	2	14.6	17	17
	18	0	1	0	0	0
	19	1	1	14.9	19	19
	Total boreal winter days with spinning effect				582	843
	Sum of last two days of each long surge				122	218
	Total without the last two days of each surge				460	625
	Probability of TC development				0.10	0.14