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

02 November 2008

BOBGRAM7 issued 2 Nov 2008

Issued 2 Nov 2008
Bob McDavitt's ideas for sailing around the South Pacific.

Disclaimer: Weather is a mix of pattern and chaos, these ideas come from
the patterned world of weather maps, so please fine-tune to your place.
Dates below are given in UTC unless otherwise stated.

Monsoon over Indonesia and Philippines is starting to drift southwards
towards the equator, but the wet season is yet to reach Darwin. There
is a Madden Julian Oscillation occurring - or, in other words, an
increase in showery activity is meandering along the Intertropical
Convergence Zone from Indonesian eastwards. This is happening mainly
along the latitude of 5 North, but I expecting an increase in activity
over Papua New Guinea/ Coral Sea area during the next few weeks - so
this could be an area to be watchful.

South Pacific convergence Zone SPCZ is in a position further south and
west than normal and has been stretching across Vanuatu to south of Fiji
to the Kermadecs area. Another branch extends along 10S from Solomons
to Tuvalu /Tokelau and occasionally visiting Northern Cooks and


The western branch of the SPCZ is clearing itself at present, but a
jetstream + tropical moisture are feeding an upper trough that has been
lingering over the Minerva /Kermadecs region. This may trigger a slack
surface low over Kermadecs on Tuesday that will move SE and fade away on

--- Hey, this system will reconfigure the subtropical ridge around about
and kill the trade winds from Southern Cooks to Fiji from Tue to
Friday--- so it is a week of light winds between Tonga/Fiji and New
Zealand. OK for sailing but it will require some motoring through areas
of slack wind.

Weak ridge starts the week in the Tasman Sea.

A trough crosses the Tasman Sea on Monday and NZ on Tuesday, avoid -it
is followed by heavy swells that reach a peak in the Tasman Sea on
Thursday, avoid.

Wednesday and Thursday -- a westerly flow.

Friday: a Low is likely to cross central NZ; it may deepen over Chathams
but will be weak over northern NZ.

On Saturday a LOW is expected to deepen in the South Tasman Sea and then
weaken as it crosses the North Island followed quickly by a ridge. This
low is worth avoiding in the Tasman Sea BUT shouldn't pose much of
problem for anyone approaching Northland... in fact the northerly flow
ahead of it will help anyone arriving Sunday/Monday 9/10 Nov. Enjoy

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