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

31 January 2009

BOBGRAM7 issued 2 Feb 2009

WEATHERGRAM
YOTREPS
Issued 2 FEB 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
South pacific Convergence zone has been most active across Coral Sea
recently breeding ELLIE near Queensland coast. There has been another
branch of activity between Solomons and Rotuma/Wallis/Futuna, breeding
HETTIE which was briefly a TC last Thursday == all in line with last
week's Weathergram.

Further east there are scattered parts of SPCZ but generally East or
Northeast winds, anticyclonic conditions and barometers above 1008,
enjoy.

HETTIE formed as a sheared system, with upper winds too strong for it to
build much height in its central core, so wind and rain from it over
Tonga was yuck but not too bad. The remains of HETTIE are somewhat
stuck in a trough that is linked to the SPCZ and lies between Fiji and
Kermadecs.
EC, NOGAPS, GFS and ww3 are handling this area slightly differently-as
an amalgam my pick is that another low will take over near Kermadecs
around Thu 5 Feb and then track southeastwards-with an associated squash
zone of southeast winds brushing past the North Island on Waitangi Day
Friday.

As an historic note HETTIE was named on the anniversary of GENE - which
was the last named TC in the South Pacific. It's the first time in the
era of satellites that a whole calendar year has gone between names ...
the main reason for this was the lack of named cyclones last Feb March.
Anyway, now that this cyclone season is well underway, it is interesting
to see the SPCZ displaced so far to south and west, truly a LA NINA
calling the shots.

ELLIE is holding together well aloft in the Coral Sea and, at present,
is forecast to approach land north of Townsville on 9am Monday local
time. A LOW of some sort is expected to stay around in the Coral Sea
all week this week, hopefully sufficiently far away from land so it can
do what TCs do (take the extra energy out of the ocean and share it
about) without too much hassle. However I'm anticipating that the
squally northerly winds on its eastern side will be encompassing New
Caledonia /Loyalties/ and parts of Vanuatu by 8 or 9 Feb.

SUBTROPICAL RIDGE / NZ
The STR is visiting NZ this week, bringing hazy lazy summer weather,
good for holidaying, but no good at all for those fighting fires or
wanting rain.

HIGH crossing Tasman Sea/NZ on 2 and 3 Feb, followed by a brief
transition trough on 3 and 4 Feb and then another HIGH taking a more
southerly path on 5 Feb, going north on 6 Feb, and another transition
trough on 7 Feb and another HIGH getting east of South Island on 8 Feb,
then a more substantial trough crossing Tasmania on 8 Feb.

So the wind for the Louis Vuitton Pacific Series near Bean Rock in
Auckland goes up and down---strong SW on Sunday due to troughing, switch
to NE winds on Monday due to ridging, easterlies on Tuesday to Friday,
maybe increasing if a low sideswipes the North Island from Kermadecs
later in the week, and possible SW change on Saturday.

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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