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

27 September 2008

BOBGRAM7 issued 28 Sep 2008

WEATHERGRAM
YOTREPS
Issued 28 Sep 2008 NZDT
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 below are given in UTC unless otherwise stated.

NIWA in NZ have issued their annual idea of the coming cyclone season in
the South West Pacific. It is likely to remain in neutral territory -
neither a La Nina nor an El Nino. Around the South Pacific previous
neutral cyclone seasons have given an average number of cyclones -
around 8 to 10. The coming season is likely to bring a REDUCED RISK of
cyclones around Northern cooks and French Polynesia. For NZ there is an
INCREASED RISK - by the time such systems reach NZ they are no longer
Tropical Cyclones but some still pack a punch. Memorable cyclones in NZ
such as FERGUS and DREANA have occurred in neutral years.

No sign of any tropical cyclones in the South pacific during the coming
week. There are some near equatorial westerly winds to north of Papua
New Guinea, and these may be heading for Micronesia, so take care there.


TROPICS The South pacific Convergence Zone, SPCZ, is having a brief
break over the Coral Sea but should reform there this week. There is
one branch over Fiji/Tonga at present and it is being propelled
eastwards by the upper westerly winds. It should fade on Tue/Wed UTC
from Samoa to Southern Cooks, but will likely trigger a LOW for form
southeast of the southern Cooks , near 30S 150W , on Thu/Fri/Sat.

A mid-latitude Low crossing NZ on Monday is likely to link into the
tropics on Tue forming a trough that crosses Fiji and Tonga on Wed, Niue
on Thursday and Samoa to Southern Cooks on Friday.


SUBTROPICS
A migratory HIGH is expected to arrive in the Tasman Sea on Wednesday
and then move east along 30S finally reaching 150W, south of French
Polynesia, the following Tuesday. These HIGHS enhance the SE trade
winds on their northern side as the pass by. In Fiji they are called
Bogi Walu (eight nights) because the enhanced trade winds give a week of
wet nights to Suva. Have fun riding these winds, going westwards.


TASMAN/NZ
Front crossing NZ on Monday should be followed by a strong SW flow on
Tuesday, and then a typical spring westerly flow until Friday. Next
front, preceded by strong NW winds, should cross the South Island on Sat
and ease over the North Island on Sunday.

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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