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

12 December 2009

BOBGRAM7 issued 13 Dec 2009

Issued 13 December 2009
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 are in UTC unless otherwise stated.

The past week was indeed busy with deep convection between Solomons and
Tuvalu, and all this has wound into the first tropical cyclone of the
season for the South Pacific. It has earned a name for itself: MICK.
This is expected to move southeast, across Fiji on Monday and Tonga on
Tuesday with gale winds, then further off into the southern Ocean, south
along 160W. AVOID.

Further east: the South Pacific Convergence zone SPCZ has been south of
its norm position lying along 20South between Niue and South of French
Polynesia, and is expected to stay in much the same place this week and
slowly fade. In tandem with this zone there is a subtropical ridge
between 35 and the eastern end of the South Pacific.

Some computer models are picking that a tropical cyclone may form off
the NW Australian Coast from Tuesday onwards and it may go south and
inland on weekend 19/20 Dec-details still uncertain - if that may bother
you then stay up to date.

A HIGH is expected to cross Tasmanian on Monday and then move northeast
across the Tasman Sea on 15-16-17 Dec, enhancing the trade winds on its
northern side and in the Cora Sea. This High should then move east,
and, once MICK gets out of the way, get past the dateline along the
subtropics at 30 to 35S from 18 to 21 Dec, enhancing the trade winds
between Fiji and Southern Cooks, and encouraging a new SPCZ to form
between Coral Sea and French Polynesia

Mediocrity: A trough is expected to cross NZ on Monday/Tuesday followed
by anticyclonic southwest flow on Wednesday/ Thursday, then, on Friday,
a strong NW flow followed by a front for the South Island. This front
should slow down and weaken over the North Island on the 19/20 weekend,
and another front is expected to move onto the South Island from the
southwest on Sunday 20 Dec.

The terms used are more fully explained in the METSERVICE Yacht Pack.
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