wjs3 wrote:wxmann_91 wrote:Yes, SST's are the main determining factor in whether we are in an "active" cycle or not. Note that we can have above average SST's but below normal activity. But relative to the climatological record, an active cycle tends to have higher total season ACE each season compared to quiet cycle seasons.
Also, I've noticed that La Nina seasons tend to have late starts, but explosive endings.
Any data on your La Nina point? It's very interesting!
WJS3
The correlation is best evidenced in +AMO (active cycle) years, so the sample size is really small, but examples:
(note that these are hurricane season that precede the Nina winter, and Nina criteria is per MEI)
1998 [Alex formed on July 27]
1999 [after Arlene, Bret formed on August 18]
2000 [Alberto formed on August 3]
exceptions would be 1995 and 2005, but they were marginal Nina years; the MEI in 95-96 only dipped below -0.5 JAN & FEB, the MEI in 05-06 only dipped below -0.5 DEC and then again in spring 2006.
85 (slightly negative AMO year) was relatively normal early with two NS's in July, but during the neutral to slightly positive AMO year 1988, the first storm formed on Aug 5.
73, 74 and 75 (73-74 was the strongest Nina recorded I think) didn't fit this at all but -AMO years tend to have more non-tropical related formations, and in fact the first three storms of 74 were subtropical and Amy/Blanche of 75 I'd suspect were from non-tropical origins, given their formation areas. 73 had one STS and one that could or could not have come from tropical origin.
Note: edited for post clarity
Last paragraph edited as it was 73-74 that was the strongest