Bob Blog 13 Oct



Compiled Sun 13 October 2019

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.

Coming cyclone Season Outlook

NIWA and MetService NZ have published their combined outlook for the coming South Pacific Cyclone season and the full details are at :


A slightly more active than normal season with 9 to 12 named storms expected.

Extra activity is expected east of the dateline (Samoa/Tonga / Niue/ Southern Cooks) especially for Feb -April 2020.

In previous similar (“analogue”) years there have been some CAT 5 storms, so the indications are this season cyclones may be more intense than normal. But next three months are expected to be close to normal, and the season starts at low risk.



The latest cyclone activity report is at and TCFP tropical Cyclone Formation Potential at

At present there are three named storms active cyclone HAGISIS off Japan, EMA in Mid-North-Pacific and MELISSA in northern north Atlantic.

HAGIBIS as the largest and most active storm Japan has had in decades and caused cancellation of some Rugby world cup games , and the practice session for F1. .



Weather Zones (see text) as expected Wednesday 00UTC showing isobars, winds, waves(magenta) STR, and SPCZ. Pink area = lightning likely (high CAPE)


SPCZ=South Pacific Convergence zone.

The SPCZ is rather weak wet of the dateline this week, but active between Samoa and noticeable between Suwarrow and Tahiti.

Passing trough over Fiji/Tonga area on Monday /Tuesday


Accumulated rainfall for next week from

Subtropical ridge (STR)

The STR remains near 20S in the NZ area .

HIGH to E of NZ on Monday moves off to the east.

Next HIGH starts forming in Tasman Sea on Mon/Tue/Wed and travels east along 30S from Thursday/Friday/Sat to east of NZ, leaving a tongue of ridge behind it. This brings a period of light winds north of NZ>.

Tasman Sea /NZ/Aus

Low deepening to 986 hPa as it travels southeast over northern NZ on Mon/Tue , moving east of NZ and starting to weaken on Wednesday.

Brief ridge on Thursday then next trough on Fri/Sat.

As for tropics to NZ this week: light winds from that High/ridge this week, large 3m+ swells as far north as 25S on Wed, and avoid arriving in NZ around 24 October. Remember that Oct 25 is a holiday in NZ.

For Noumea to Aus looks Ok after westerly winds swing to S/SE near New Caledonia on Monday.

Tahiti to Tonga

Mainly trade winds this week but passing trough over Tonga on Tuesday with showers.


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