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

25 December 2009

BOBGRAM7 issued 26 Dec 2009

WEATHERGRAM
YOTREPS
Issued 26 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.

TROPICS
This edition is earlier than normal and next one will be later than normal as I'll be travelling around during next week.

It looks to me as if we will have another reasonably quiet week in the South Pacific.
South Pacific Convergence zone SPCZ has split into three entities, but maybe they are still linked in some way.

Convergence zone1 is active in eastern Coral Sea, but this may weaken this week. Convergence zone2 extends from Tokelau to Southern Cooks. A tropical LOW within this zone is likely to cross the Southern cooks on Mon 28 Dec UTC and then deepen as it peels off to the southeast, stealing away the wind from the tropics.

A third convergence zone is draped over French Polynesia and will hover around there all week, this often happens in an El Nino.

SUBTROPICS
HIGH just north of NZ today is blocked and will fade where it is by Wednesday.
The enhanced trade winds on its northern side from Niue to New Caledonia and NE winds from New Caledonia to Queensland will also fade.

Next High rolling in from the eats is likely to cross Tasmania on Tuesday 29 Dec, killing the wind for the Sydney-Hobart racers, and then move northeast across the Tasman Sea and reach Northern North Island on 1 January. So that Tasman Sea pattern is almost a repeat if last week's.
This High should be able to get further east than its predecessor along 30 South during 1-2-3 January, so that then the enhanced trade winds on its northern side may extend from French Polynesia to New Caledonia, and the SPCZ may reform along 10 South.

NEW ZEALAND AREA:
Fronts have been side-swiping southern NZ during past week, knocking on the door but higher pressures have killed them.
Now that the High over northern NZ is expected to have dropping pressures, the next front should be able to open the door and spread across NZ – preceded by strong NW winds, crossing South Island on Tuesday and North Island on Wednesday, and be followed by a strong cooling SW flow until Thursday. Then the idea is for a disturbed westerly flow for a few days.

I'll leave you all with these last few verses from Robbie Burns to mark the finish of the first decade of the second millennium:

We two have paddled in the stream,
from morning sun till dine† ;
But seas between us broad have roared
since the days of auld lang syne.

For auld lang syne, my friend,
for auld lang syne,
we'll take a cup of kindness yet,
for the sake of auld lang syne.

And here's a hand my trusty friend!
And give us a hand o' thine!
And we'll take a right good-will draught, for the sake of auld lang syne.

The terms used are more fully explained in the METSERVICE Yacht Pack.
More info at http://weathergram.blogspot.com
Feedback to bob.mcdavitt@metservice.com

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