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

26 February 2011

BOBGRAM7 issued 27 Feb 2011

WEATHERGRAM
YOTREPS
Issued 27 February 2011
Bob McDavitt's ideas for sailing around the South Pacific.

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

That Christchurch quake was devastating. Kiwi people are all one family
and all suffering shock together this week. NZ Govt has set up a fund
to help recovery at christchurchearthquakeappeal.govt.nz

TROPICS
La NINA is still strong, and has strengthened a little in the past week
with its 30day running mean rising from 1.9 on 19th to 2.14 on 26th.

There are falling pressures and persistent convective rain over much of
northern Australia, and this rain is likely to move inland and
southwards this week.

South Pacific Convergence Zone SPCZ was cleaned out when Tropical
Cyclone ATU was vented from the tropics last week. SPCZ is now slowly
redeveloping in the trough left behind, from Solomons to Vanuatu and
then scattered over Fiji and Tonga. East of this zone the flow is
generally from E or NE, and to the west there are light winds over the
Coral Sea.

SUBTROPICAL RIDGE:
HIGH1 is wandering east along 40S to east of NZ and should reach 140W by
5Sat 5 March... the trough on north side of this High is expected to
deepen into a LOW near 30 to 35S around 150 to 160W from Fri 4 March and
there will be a squash zone between this Low and HIGH1. Avoid.

HIGH2 in the Australian Bight is expected to move east across Tasmania
on Sat 5 March, pushing a cold southerly onto NZ on Sat 5 March. This
means there is a long gap between highs over Taman Sea /NZ area and
maybe enough delay so that a LOW may form off Queensland on Fri 4 March
and reach North Island early next week, preventing HIGH2 from getting to
NZ. This scenario may change (read next weathergram).


NZ Area
Weather maps show a trough-troubled week ahead. Low from Tasman Sea is
expected to cross southern NZ on Tuesday 1 March followed by a brief SW
change on Wed 3 March. A much colder front followed by southerly wind
is expected to cross NZ on late Fri 4 March/Sat 5 March, weakening and
stalling over Northland for the weekend. === Another challenging week
for the Round North Island Race fleet


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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