Translator

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

01 November 2009

BOBGRAM7 issued 1 NOV 2009

WEATHERGRAM
YOTREPS
Issued 1 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.

As the calendar ticks into the month that is regarded as the start of
the cyclone season, and into the traditional time that yacht weather
damage is not covered by insurance in the tropics of the Southern
Hemisphere, yachts tend to migrate from the South Pacific Islands to New
Zealand or Australia.

There have been four damaging cyclones over the Philippines in the past
month-one a week-so the Northern Hemisphere cyclone season is still
having its last hurrah.

The South Pacific Convergence Zone SPCZ was more active than normal in
the past few weeks-and had some northwest winds on its northern side
making for troughing conditions-briefly a LOW formed on it in the Coral
Sea, but it appears to be easing now. It is draped from Coral Sea
across northern Vanuatu to Wallis and Futuna to northern Tong and then
southeastwards to be sort of mid-way between Southern Cooks and French
Polynesia. A small low might form on the SPCZ to south of southern
Cooks around Fri 6 November, but if it does it will just peel off to the
southeast and fade.

It looks as though the SPCZ may move a little south this week, perhaps
reaching Fiji on Tuesday 3 Nov and southern Tonga on 4 to 5 Nov, but it
also appears to be fading.

So the cyclone season starts with a low risk of any disturbances this
week.


CROSSING THE SUBTROPICS and HEADING FOR NZ The subtropical HIGHS
dominate proceedings this week, basically killing the wind along 30S.
Heading for NZ this week from Tonga or Fiji is good for motor vessels,
but yachts looking for sailing winds all the way should wait until next
week, maybe longer.

One HIGH is already in evidence on the central Tasman Sea and should
slowly get into the north Tasman Sea on Monday Tuesday 2-3 Nov and then
slide east along 30S as it fades on Wednesday/Thursday 4-5 November.
There will be a small but noticeable increase in the trade winds over
Fiji and Tonga on Wed and Thursday 4-5 Nov as this High glides by - a
small squash zone.

On Friday to Monday 6 to 9 Nov, and maybe longer, a new HIGH is expected
to build in the Tasman Sea, enhancing the trade winds between New
Caledonia and Queensland.


Between these highs, on 4 and 5 Nov, a heat trough is likely to over
inland Queensland, turning winds along its coast to come in from the
northeast.

Through all this, all week, New Zealand should remain in a disturbed
southwest flow, with one front crossing on Mon-Tues 2-3 Nov, another on
Wed-Thu 4-5 Nov, and a third brushing past the South Island on Friday 6
Nov. Boats heading for Northland should find Wednesday or Friday and
Saturday will be the best days to make landfall.

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

No comments:

Blog Archive