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

14 November 2009

BOBGRAM7 issued 15 Nov 2009

WEATHERGRAM
YOTREPS
Issued 15 November 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.

Tropical cyclone ANJA in the South Indian Ocean has started the Southern
Hemisphere cyclone off. It was perhaps helped by a pulse of extra
convection called a Madden Julian Oscillation, and this pulse is
expected to reach the equatorial western pacific around 20 to 30 Nov...
so the next few days marks the end of a relatively quiet period for the
South Pacific Convergence Zone SPCZ and next week may mark the beginning
of some extra convection in our part of the world.

Those cruising yachts still looking for a trouble-free trip to NZ or
Australia had better set off this week.

SPCZ has recently been extending from Solomons/Northern Coral Sea to
northern Vanuatu and from Tuvalu to Samoa to French Polynesia FP.

The section over FP is likely to develop a small tropical low or two
on Mon -Tue 16-17 Nov, UTC, and this will then peel off to the
southeast, leaving behind typical convergence zone conditions of light
variable winds and a few tropical squalls.

A branch of the SPCZ in the Coral Sea is likely to spread across Vanuatu
and New Caledonia from now to Tuesday 17 Nov and then fade. This zone
is embedded in a easterly flow ,around 10 knots on the north side of the
zone, around 20 knots on south end of zone and squally within the SPCZ.

The branch from Tuvalu across Samoa to FP should stay in place this
week, with ENE winds 10 knots on its northern side. SE winds 15 to 20
knots on its southern side and squally within a 5 to 7 degree wide zone.


Less wind in the Coral Sea than there has been over past few weeks.

TASMAN SEA/NZ
HIGH fills the subtropics along 28S from 160E to 160W today is expected
to turn into a wind flow from the east in the area west of the dateline
by Tuesday 17 Nov, and in the areas east of the dateline by Friday 20
Nov. This makes sailing south to NZ or west to Australia a reasonable
prospect this week. Go for it before the MJO turns up J

LOW is expected to cross Tasmania on Monday 16 Nov and then peak in the
central Tasman on Tue 17 Nov and cross NZ on wed 18 Nov and then fade
over Chatham Islands on Thu 19 Nov. The NW flow ahead of its front may
be useful for yachts making landfall in Northland early on Tue 17 Nov.
However the SW winds around Northland on Wed-Thu 18-19 Nov will be in
the face of incoming boats.

Next HIGH is expected to take a path further south than the last-may
bring some warmth with it. Should cross Bass Strait on Tue 17 Nov,
central Tasman Sea on wed 18 to Fri 20 Nov, and then have centres west
and east of North Island on Sat-Sun 21-22 Nov. OK for sailing south-may
have to motor near Northland on Fri-Sat 20-21 Nov.

South of this High, a passing front should bring strong NW winds to
southern NZ on Fri-Sat 20-21 Nov along 35S


I will be at Swordfish Club in Russell around 5:30pm this sat evening 21
Nov, talking LOCAL WEATHER.

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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