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

23 August 2009

BOBGRAM issued 23 Aug 2009



Issued 23 August 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.


We start the week with TCs Bill, Hilda and Vamco in the Atlantic, NW and NE Pac respectively.   Bill should sideswipe Nova Scotia, Hilda should fade south of Hawaii, and Vamco should wander north.

As for the South pacific - well, the main part of the South Pacific convergence Zone SPCZ has wandered to the northern part of its zone.. from Solomons to Samoa to Southern Cooks.  There should be a burst of activity near the Southern Cooks on Monday /Tuesday UTC, and another between Tuvalu and Samoa /Tonga on Sunday and Mon 30/31 Aug UTC.


The High positioned in the North Tasman Sea and covering New Caledonia today is expected to move along 30S and fade near the date line on Wednesday, enhancing the trade winds in the Coral Sea.

Next High is expected to be stronger and larger, and should build in the Tasman Sea near 33S on Thursday, Cross the North Island on Friday, and 

Wander east along 33S after that reaching French Polynesian longitudes on 1/2Sep, all the while with a squash zone of enhanced trade winds on its northern side.    As it wanders east of 140W around 2 Sep, a LOW should form on its North-western shoulder near Niue. Avoid.


That LOW which has been hovering off the NE of NZ last few days should wander slowly along 30S as a multi-centred feature with one of the centres deepening at 30S near 155W or south of French Polynesia on Wednesday, bringing them a touch of westerly winds on Wednesday and Thursday UTC.

A front is fading over north-western NZ this evening.  Next front should move onto SW of South Island on Tuesday and North Island on Wednesday proceeded by northerly winds and followed by a northwest flow.

On Thursday another front should cross NZ proceeded by NW winds and followed by westerlies.  This front may well have thunderstorms.

Next front is likely to reach SW of south Island late sat and cross NZ on Sunday, preceded by NW flow and followed by a S to SW flow.  This front is probably the best of the bunch for going north but still not ideal.

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

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