Bob McDavitt's ideas for sailing weather around the South pacific

15 May 2016

Bob Blog15 May



Issued 15 May 2016


Bob McDavitt's ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world.


The Tropics

Several annual outlooks for the North West Pacific 2016 cyclone season have been published. The first forecast for the year was issued by CSU on December 11, who anticipated that one of four different scenarios could occur. TSR subsequently issued their first outlook for the 2016 season during December 16, 2015 and predicted that activity would be about 20% below the 1950–2015 average, or about 15% below the 2005–2015 average. Specifically they thought that there would be 13 tropical storms, 5 hurricanes, 2 major hurricanes and an ACE index of 79 units. A few months later, TSR issued their second prediction for the season during April 6, 2016 and lowered the predicted number of named storms to 12 but raised the number of hurricanes to 6. On April 14, CSU predicted that the season would be near-normal, predicting 13 named storms, 6 hurricanes and 2 major hurricanes with ACE near 93. On April 15, North Carolina State University predicted the season would be very active, with 15-18 named storms, 8-11 hurricanes and 3-5 major hurricanes. A month later, the United Kingdom Met Office (UKMO) released its forecast, predicting a slightly above-average season with 14 named storms and 8 hurricanes. It also predicted an ACE index of 125, being the average ACE index 103.



Nothing much happening at present. We await the onset of the Indian Monsoon. Mid to late May is the Everest ascent season, and indeed there has been ascent during the past week. Once the Monsoon starts, that’s it for climbing Everest because jetstream winds return to the Himalayas.


Rain maps for the past fortnight show that the extra convergence zone that has been located between Galapagos and Marquesas has now faded. Wet clouds are starting to approach India from the south. Downpours in the SPCZ brought floods to parts of Samoa last week.


Rain for the past fortnight from



SPCZ=South Pacific Convergence zone.

SPCZ is expected to remain draped from PNG across northern Vanuatu to the Samoa area, with another branch that is over Tahiti and Tuamotu Islands relaxing from local Monday to Thursday.


STR= Sub-tropical Ridge

The BIG FAT HIGH that was to northeast of North Island last week had faded and is moving off to the east. The STR is expected to spend a few weeks weak and along 30S, allowing a series of troughs to travel across the Tasman Sea and New Zealand area.


Voyage Outlooks:

Panama to Galapagos:

Light winds for departing from Panama this week, and with a northerly touch to them on Monday and Tuesday.


Travelling to Marquesas:

Winds near Isla Isabela are expected to be southerly between 4 and 12 knots this week. May as well get best from the current by going to 5S 130W and then direct. Light winds are expected over Marquesas until local Tuesday and then a convergence zone with showers for Wednesday to Friday, then a day or so of 20 to 30kt SE winds and then better conditions next week.


Tahiti to the west

The WARC fleet are heading west from Tahiti this week, mostly going to Suwarrow, see

The SPCZ has been active last week over Tahiti and Tuamotu but is expected to quieten down from local Monday to Thursday, so that offers a good opportunity for departure. Light winds are expected locally for the next few days. The gap in activity extends west wards to Suwarrow this week, but SPCZ is likely to reactivate after 21 May, more so to north 15S.


Between NZ and the tropics

The  Sea Mercy fleet  have mostly departed Opua for Minerva. Yachts can be tracked using the YiT website at

There may be problems getting away from NZ this week. 

There is a series of fronts all lined up ready to move onto North Island.

Monday's front is just an entrée. Wednesday’s may be the thundery one. And Friday's may turn into a LOW and be longer lasting --until perhaps Tuesday 24 May. It looks as though, during this period, it may be better to stay put so as to avoid the strong winds off the Northland coast every other day. However there may an opportunity to get away between fronts on Tuesday.


Between Australia and New Caledonia

The “Go East” Rally is considering departure around 7 June from Southport Yacht Club to Noumea, and some early birds are departing from any Aussie eastern seaboard before that. See!go-east-the-about-go-east-rally/c5ve

Southport starts this week in the light winds of the Subtropical ridge. A useful southerly wind for sailing is expected to arrive on or around Thursday, and this can be taken to Noumea as a track to east in S winds then direct in SE winds. Another option is to depart on Wednesday and go direct, staring by motoring in light winds then sailing in SSE/SE winds. Nice weather this week and start of next week.



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