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

02 November 2014

Bob Blog

WEATHERGRAM
YOTREPS
Issued 02 November 2014
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 TROPICAL TOPICS Tropical cyclone activity at present
includes VANCE off the west Mexican Coast and NURI off the east of Japan.
Weekly rain maps show that the main rain has been associated with tropical
cyclones. In the South Pacific the convergence zone seems to have cleared
last week over northern Vanuatu and intensified from northern Fiji to Samoa.
Otherwise not much change.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ is steady in position and fluctuating in intensity and expected to be
weaker this week than last week. Many over the sea between Solomons and
northern Vanuatu, with another branch from northern Fiji to Samoa extending
SE towards French Polynesia.
Part of the energy from the SPCZ is expected to help deepen a low in the
mid- latitudes near 35S 150W (South of French Polynesia) by Wednesday.

STR= Sub-tropical Ridge
The STR has been strong during October.

High between Tonga and NZ today is expected to stall near 30 to 40S 160W
from Tuesday to Thursday and then fade  should maintain steady ESE winds in
the tropics on its northern sidemay be somewhat enhance along 12 to 18S
from 165 to W to 180.
Second HIGH crossing Tasmania on Monday is travel NE onto northern NZ by
Friday and then travel east away from northern NZ early next week.

Between the tropics and NZ
Vessels in the All Points Rally (www.islandcruising.co.nz/?page_id=1687)
are mostly underway now with a good weather pattern for sailing to Opua, NZ
from Tonga, Fiji, or Vanuatu. This rally is free of charge (thanks to the
sponsors) and helps participants with planning, weather info, clearance, and
seminars on how to enjoy NZ.

The first factor to consider a departure date is the local weather: the
SPCZ does have some convective cloud over northern parts of Fiji at present
but is not very intense and isn't really strong enough to delay departure
this week.

The second restraint on a weather window is to pick an ETA over northern
NZ that does NOT have strong adverse winds. Northern NZ is expected to
have a period of light winds early next week as the second High mentioned
above passes bylooks good -- until Wed 11 Nov when the next front and SW
winds arrive.

The third factor is to avoid gales and heavy swells during the trip.
Good news is there isn't much to report this week. The replacement trough
between the Highs is crossing the North Island on Monday and may form a
little secondary low east of the North Island on Wednesday/Thursday, but
this doesn't affect Northland. There is a possibility that a week tropical
trough may cross the region between Fiji and NZ on Sunday 09 /Monday 10 Nov
 that could form some showers and enhance the easterly winds just north of
NZ and so shouldn't be a hassle and may be a help.

Minerva is likely to have winds between ENE and ESE 10 and 20 knots this
week with swell from E then S then SE around 2 metres.

See my yotpak at boatbooks.co.nz/weather.html for terms used.
Weathergram text only (and translator) is at weathergram.blogspot.co.nz
Weathergram with graphics is at metbob.wordpress.com, click FOLLOW at bottom
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