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

13 June 2010

BOBGRAM7 issued 13 June 2010

WEATHERGRAM
YOTREPS
Issued 13 June 2010
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.

Galapagos to Marquesas: Apparently some are still "puddle jumping"---
There is a good west going current to be found at around 30 miles north
of the equator . Take this to around 123 W and then head direct for
Marquesas. Weather is looking settled this week.

TROPICS
South Pacific Convergence zone SPCZ is active mainly in the Eastern
Coral Sea, with scattered areas along 10S near Tuvalu to Tokelau/Samoa.
This week the convection to north of New Caledonia is expected to drift
east, and form a trough to east of New Caledonia. Around Wed 16 June a
low should start to form in this trough and then deepen and travel SE
to east of North island and South of Kermadecs by Sat 19 June. There
will be a squash zone between this LOW and a HIGH over NZ on 16 -17
June.

Anyone taking the opportunity to sail north from NZ when the SW winds
start easing on Mon 14 June and heading for Fiji or Tonga should ensure
they go clock-wise around this low and its squash zone.

SUBTROPICAL RIDGE: STR
HIGH should cross the Tasman Sea on Tue/Wed 15/16 June, and North Island
on Wed 16/Thu 17 June, and then move smartly along 40S to be south of
French Polynesia by Mon 21 June. Its migration to the east will be
accompanied by a squash zone in the trade winds on its northern side ,
mainly along 20S.
Good to see this pattern return, as it is the regular winter pattern.
That LOW mentioned as forming in the tropics will probably wait for this
High to get out of the way first.

Next HIGH may be delayed and knocked to 45S and move into South Tasman
Sea south of Tasmania on 22 June.

TASMAN/NZ
The arrival of the Wed/Thu High coincides with the start of the National
fieldays which I will be attending this week. Fog and frost will be on
the menu.

A front should cross NZ on Fri 18/sat 19 June following this High, but
this is expected to fade as it comes, so will not bring a SW change to
Northland.

A Low is forecast to form off the Queensland coast on Fri 18 June, and
this should move SE across the North Tasman Sea and then across
Northland around Tue 22 June Tuesday. This LOW may or may not be
able to time its arrival along with the outbreak of cold southerlies
that will be shovelled onto the South Island by the next HIGH. So NZ
may be in for another cold S/SE outbreak early next week.

This means that the NEXT SW wind change in Northland for good sailing
to the North has been delayed to maybe the end of next week /maybe the
end of the month. Tomorrows "window" closes quickly too.

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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