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

21 August 2016

Bob Blog 21 Aug

Issued 21 August 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.

I have been informed of another blog about navigating in the Pacific by
downloading Google earth, BING, and some other maps and viewing them offline.
This blog is from Art of SV Feeling Good, and gives the link to a program/Ap
called OVITALMAP which can be downloaded to iPad, Android or Windows. It comes
from China but has reasonable English. It doesn't get around the lacunae which
occurs on Google earth and Bing, but does allow you to download the data for
offline viewing.
I have shared this on my Facebook page.

If you are in Fiji tomorrow remember that the whole nation is having a public
holiday to help congratulate their rugby sevens team for winning a gold medal in
the Olympics.

The Tropics
That tropical low which went inland from the Gulf of Mexico and flooded
Louisiana in the past week was a "Hurricane without high winds". In this
changing planet, these beasts seem to be happening more frequently than in the
past century or more, and may need a system to help with warning the public.
An interesting article on this can be read at

And an explanation of why it happened is at
Over in Asia the monsoon, now in its last month, has had a fling in India, with
over 30 deaths in the last few days. It has been a wetter than normal monsoon
overall so far.
As seen at

Busy at present in the NW Pacific with cyclones having a party around Japan:
Elsewhere we have a decaying FIONA in the Atlantic:
And we are now up to K for KAY west of Mexico:

The rain maps for the past weeks (see shows a build-up
of convective activity in the Asian Monsoon and in the SW Pacific for
Vanuatu/Fiji/Tonga ( A visit form the SPCZ, now fading).

SPCZ=South Pacific Convergence zone.
SPCZ has faded over Fiji and Tonga during the weekend and is expected to
redevelop over Samoa to east of Niue around mid-week, then fade away by weekend.

Should cross the Tahiti area around Fri 26/Sat 27 August local.

This week's SPCZ may be seen on with rain accumulation and six days,
from, using ECMWF data

STR= Sub-tropical Ridge
HIGH east of South Island tonight is moving off to the East. Another High cell
is expected to travel east along 30/40s from Northland area on Monday to south
of French Polynesia next weekend.

Voyage Outlooks:
Tahiti to the west
There is likely to be as quash zone of enhanced trade winds between French
Polynesia and Vava'u from Tue to Sat/Sun 27/28 August local. Avoid.

Between NZ and the tropics
Weak trough is expected to cross northern NZ on Monday.
A series of fronts, some with strong winds, are expected to affect Northern NZ
from late Wed to around Sun 28 August. If you are quick and keen then TUESDAY
is the day to depart.

See my yotpak at for terms used.
See my website for information on tailor-made voyage forecasts-
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