Bob Blog 4 Nov 2018



Compiled Sun 4 Nov 2018

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.


Sea Surface temperature anomalies as at start of November may be seen


The eastern equatorial Pacific around Galapagos is the focal region for ENSO and is now on a steady warming trend. Cyclones have been stirring the seas between Mexico and Hawaii, making avenues of cooler surface water. There is a zone of warmer seas from Solomon Island to Samoa. Temperatures around Australia and the Tasman sea remain below average, a possible indicator of drier than normal conditions in the next month or so. Also, this should cool the southwest winds that reach New Zealand.

The Gulf Stream off the east coast of North America and the Kuroshio current off Japan still stand out but not as much as last month.

To see how the annual weather cycle and the seasons are working out, check the average isobar maps from

Average isobars for past 30 days and their anomaly:


The subtropical ridge in the southern hemisphere has intensified during October

Zooming into the NZ area, the 1015hP (between blue and white) isobar has shifted to south of New Zealand. And the 1020 has spread east into the Tasman Sea. The 1010 isobar near the equator has disappeared.


OCTOBER       image

The last 30 days of rainfall, and its anomaly are seen at



The rain map shows extra convergence around equatorial Indian Ocean.


Latest cyclone activity as seen at


XAVIER is expected to stay offshore.

Looking at the weekly rain maps, last week’s shows an increase in activity across the equatorial Indian Ocean, and a relaxing of convection around Papua New Guinea and the Mariana Islands. Not much change elsewhere.





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 sitting over northern Coral sea and northern parts of Vanuatu across Wallis and Futuna to northern Tonga, and part of it may travel southeast to Southern Cooks this week.

Accumulated rainfall for next week from CZ= convergence zone.


Subtropical ridge (STR)

High is travelling east along 25 to 35S past northern NZ from Monday to Friday and the expected to linger to east of New Zealand until early next week.

Tropics to New Zealand

Trough from the Tasman Sea is expected to spread onto central New Zealand by Fri 9 Nov and then stall, so that a zone of cloud and rain with light winds spreads onto northern NZ by Tue 13 to Thu 15 November. It looks OK to arrive in NZ with this trough.

Between Tropics and Australia.

Avoid a passing trough across the northern Tasman Sea on Wed and Thursday with light variable winds.

From Tahiti to Tonga

There may be a trough forming near Niue around Sunday 11 November, otherwise the forecast is for useful easterly winds.


If you would like more detail for your voyage, then check to see what I offer.

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Weathergram archive (with translator) is at

Contact is or txt 6427 7762212



Published by metbob

Pattern and Chaos

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