Cyclones in the Society Islands and El Nino: Considering options for cyclone season
John & Julia Freeland of S/V Mary Ann II will pass the circumnavigation mark on the way from the Galapagos to Hiva Oa next month. In 1998 they spent cyclone season in American Samoa, but this season hoped for a longer cruising season in French Polynesia. In trying to double check the figures re. the risks of cyclones in the Society Islands, John has shared his observations with noonsite.
Published 7 years ago, updated 4 years ago
In considering options for cyclone season, the option (for EU boats anyway) of staying in the Society Islands has higher risks than say the Marquesas. But when the El Nino cycle is considered, the Society Islands’ risk drops significantly based on cyclone history.
In a newspaper article about the 1997 “Gonzilla” El Nino, it was noted that French Polynesia was hit in the 1905-1906 El Nino year then spared until the 1982-1983 strong El Nino cycle when five storms affected the region. I could find 7 cyclones since 1983 which significantly impacted French Polynesia (internet searches.) I then listed the ONI data, which is a measure of the El Nino / La Nina cycle that tracks ocean temperatures.
Positive numbers above +0.5 to +2.3 are required for El Nino and negative numbers -.5 to -1.7 is defined as La Nina. Here are the cyclones since 1983 and the ONI index values for the month and year that each occurred. All occurred during an El Niño designated period except Niko.
- 1991 Wasa-Arthur +1.4
- 1997 Martin +2.3**
- 1997 Osea +2.3**
- 1998 Alan +1.0**
- 2007 Arthur +1.3
- 2010 Oli +1.4
- 2015 Niko +0.5*
*Niko is the only anomaly – but just barely. It came 343 miles SW of Tahiti in January 2015. El Nino is defined as 5 or more “consecutive” 3-month blocks above +0.5 and here are the figures. Due to the dip in the Jan-Feb- Mar figures, which dropped to +0.4 (just below the +0.5 cut off), the January (DJF) block is not technically during an El Nino although above the cut-off value of +0.5.
3 MONTH BLOCKS
# Niko #
Bold months are classified El Nino
SON OND NDJ #DJF# JFM FMA MAM AMJ MJJ
+0.4 +0.6 +0.6 #+0.5# +0.4 +0.5 +0.7 +0.9 +1.0
The 1982-83 season is more difficult to precisely research, but suffice it to say it was one of the worst cyclone seasons on record and clearly the worst for French Polynesia. The season occurred during a strong El Nino period.
Finally, as of May 2016, all models show a switch from El Niño to La Nina in the coming few months.
The Society Islands appear to me to be a relatively safe option for spending cyclone season during a La Nina period, and probably during most neutral periods. I would be more circumspect during periods in which models are predicting an impending El Nino.
I welcome thoughts on the subject.
I will pass the circumnavigation mark on the way from the Galapagos to Hiva Oa next month. In 1998 l spent cyclone season on Mary Ann II, my Westsail 32, in American Samoa, but this season hoped for a longer cruising season in French Polynesia with my wife, Julia.
Caveat: I’m no meteorologist, but I have tried to double check the figures. Hopefully, this is food for thought.
This is a visual description of the ENSO and SP cyclones: http://reliefweb.int/map/indonesia/pacific-region-historical- storm-tracks- months-nov- Apr-1956- 2009-different- enso [BROKEN LINK]
S/V Mary Ann II