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

17 January 2009

BOBGRAM7 issued 18 Jan 2009

WEATHERGRAM
YOTREPS
Issued 18 JAN 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
Some parts of Fiji measured over a metre of rain in the past fortnight.
The remains of this MJO event- a pulse of extra convection moving east
across the South Pacific-are visiting French Polynesia early this week
along with some wet northwesterly winds.

The South Pacific Convergence Zone now stretches in a broad area from
North Australia across the Coral Sea to Vanuatu (with a side branch over
the Solomons) and then to South of Fiji. This branch is weakening and
expected to stay put or drift south this week, with NE winds on its
northern side, slack winds in its middle and SE winds on its southern
side.

An eastern branch of the SPCZ stretches from near Tuvalu/Samoa, between
the Northern and Southern Cooks to southern French Polynesia. This
zone is active near French Polynesia and may develop a low pressure
system near Suwarrow/ Suvarov from Tues 20 UTC that may deepen and cross
Southern Cooks on Friday 23 UTC. If you are in this area get updates
and brace for wind/rain.

SUBTROPICAL RIDGE
A HIGH is forming in the Tasman Sea today ... it should move slowly
along 35S and cross the North Island/central NZ from Wednesday to
Saturday, with a zone of enhanced trade winds on its northern side
slowly covering most of the South Pacific between 20 and 30S. There
will be a squash zone between the subtropical ridge and that low which
is likely to be crossing the Rarotonga area on Friday 23 UTC. This
squash zone is likely to reach its peak near 30S 160W on Sat 24 Jan UTC.
Avoid.

TASMAN SEA/NZ
South to southwest flow over New Zealand should last until Tuesday.
Then, until Saturday, that HIGH is likely to dominate the North Island
with light winds and settled weather -- whilst a northwest flow is
likely over the South Island coming from the hot interior of Australia
(some of this wind will be redirected through Cook Strait). Fronts
embedded in this NW flow are likely to lap onto the south on Wednesday,
Friday and Sunday with the last of these followed by a cooler southerly
change on Sun/Mon 25/26 Jan.

PS: I've just noticed that someone's stolen my bike - it was locked
outside this office and now it's gone. So make extra sure your stuff is
safe this week.

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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