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

03 August 2008

BOBGRAM7 issued 3 Aug 2008

Issued 3 August 2008 NZST
Bob McDavitt's ideas for South Pacific sailing weather.
(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

South Pacific Convergence Zone SPCZ is well no from the northern part of
Solomons to Tuvalu/Tokelau to Northern Cooks. It'll probably start to
extend southwards this week and get to Samoa next weekend.

Some of its moisture is likely to branch off to the south across the
Coral Sea on Thu 7 Aug (all dates UTC) and join with a trough then
crossing the Tasman Sea so that a wet trough reaches New Caledonia on
Fri 8 Aug (in time for start of the Olympics) - accompanied by variable
winds and squally showers -- and this trough will then move southeast
across Kermadecs on Sat 9 Aug. Also on 8 Aug UTC another trough
(rather weak) is likely to move eastwards across French Polynesia
accompanied by some squally showers and variable winds.

Otherwise it is likely to be a weak of trade winds in the SW Pacific.

The LOW that passed over NZ last week was a slow-mover. It was blocked
by a zone of higher pressures to south and east of it. Blocking is
something that adds grunt to NZ's winter storms, and it looks as though
it may hang around for the next few weeks. So a few more Lows from the
Tasman are on the menu - but this week there'll first be a break in the
pattern with a passing High.

This incoming HIGH will bring us a welcome break in the recent wet windy
weather. It's sitting over eastern parts of Australia today (3 Aug) and
expected to peel off into the Tasman on 4th then wander over NZ on
5-6-and much of 7th with dry weather and light winds. Good for fishing.

On Thu 7th the next trough will start deepening in the Tasman Sea,
preceded by northerly winds, accompanied by rain, and followed by
squally SW winds. This trough is likely to cross NZ on 8-9 Aug,
followed by a disturbed west/southwesterly flow on 10-11 Aug, turning
colder southerly on 12-13-14 Aug.

The terms used here are more fully explained in the METSERVICE Yacht
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