Bob Blog 18 Oct 2020

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.

Compiled Sun 18 Oct 2020

After 5 doses of radiology, I’ve been discharged from hospital and so I’ve returned to blog writing, for now.

The Bureau of Meteorology, Australia, have issued their Outlook for the coming Cyclone season. Usually there are 11 cyclones in Australian waters with around four making landfall. However, more cyclones than average are likely for Australia during Nov 1 2020 to 30 April 2021. This is due to La Nina conditions in the tropical Pacific Ocean, and somewhat warmer than average ocean temperatures in Tasman Sea and to north of Australia. In La Nina years the first cyclone to develop around Australia usually occurs earlier than normal, around mid-December.


The Tropics

The latest cyclone activity report is at and Tropical Cyclone Potential is from

After a rush of cyclones in the past few weeks, it is currently quiet, but there are four areas of interest, and two zones of high potential for formation around the Philippines and the Mexican East coast.



Weather Zones (see text) as expected Wednesday 00UTC showing isobars, winds, waves(magenta), Rain (Blue), CAPE (pink), STR, and SPCZ.


Predict wind CAPE mid-week gives two possibilities for SPCZ


SPCZ=South Pacific Convergence zone.

SPCZ is expected to stretch from Solomon Islands to norther Vanuatu to between Fiji and Samoa. Trough over Tonga/Niue area today moving off to SE and across Southern Cooks with some 3m swells tomorrow.

Accumulated rainfall for next week from


Subtropical ridge (STR)

HIGH 1020-22hPa northeast of northern Z on Mon travelling east-southeast to 35S by mid-week, when it joins with another High travelling along 45S to east of the South Island. And this is followed by Friday with a NW flow over NZ.

Tasman troughs

Low in south Tasman Sea today, travelling across the South Island on Monday at 1000hPa, followed by SW flow on Tuesday.

A trough is likely in northwest Tasman Sea on Tuesday/Wednesday, weakening away on Thursday.


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

Or Facebook at /

Weathergram with graphics is at (subscribe/unsubscribe at bottom).

Weathergram archive (with translator) is at

Contact is or txt 6427 7762212


Published by metbob

Pattern and Chaos

Join the Conversation


  1. Hey Bob,

    Pleased to hear you’re out of hopsital. our thoughts are with you.

    Sincere Regards

    Ray & Sharyn SV Jasper II

Leave a comment

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.