Bob Blog 23 Oct 2016

WEATHERGRAM
YOTREPS
Compiled 23 October2016

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 CYCLONE SEASON OUTLOOK
The South Pacific/Australian tropical cyclone season is from nominally from 1
Nov to 30 April. A neutral to weak or moderate LA NINA is expected to affect the
tropical Pacific Ocean over the next six months. This tends to nudge the South
pacific convergence zone to the south and west of its normal position,
increasing the cyclone risk around Australia and Coral Sea, and perhaps reducing
this risk in places east of the dateline.
The Bureau of Meteorology have considered this and say that the cyclone risk
over Northern Australia is increased. The average number of cyclones per season
across the entire region is 11.
See more at www.bom.gov.au/climate/cyclones/australia/

Looking at the behaviour of the sea surface temperature over the past year, NIWA
has searched the database for analogue years that may point the way as to how
this season may develop. The top analogues are 1969/70; 1983/84; 1992/93;
1995/96; 2005/06; 2010/11 and using this data they have compiled a cyclone risk
map, as
at www.niwa.co.nz/news/southwest-pacific-tropical-cyclone-outlook
They have applied these risks to the average occurrence of tropical cyclones to
come up with a map showing likely numbers of TC in each sub area this season.
See www.niwa.co.nz/news/southwest-pacific-tropical-cyclone-outlook
The average number of cyclones across the South Pacific region per season is
12.4 cyclones.

TROPICS
Philippines got a double hit last week from TC SARIKA (KAREN in the Philippines)
and HAIMA (LAWIN in the Philippines).
NASA have produced a video showing the resulting extreme accumulated rainfall at
www.eurekalert.org/pub_releases/2016-10/nsfc-nme102116.php

At present there are two tropical depressions that are being forecast by the
computer models to become cyclones this week (one in Northern India Ocean and
one west of Mexico), and there possible fture tracks are seen at
ruc.noaa.gov/tracks/

Rain accumulation maps show the two cyclone tracks over the Philippines, and the
track of NICOLE in the Atlantic, and a rebuild of the South Pacific Convergence
Zone.
These may be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES

This is the time of year that yachts are staging themselves in Tonga (or Fiji or
New Caledonia) and waiting for the right weather pattern for sailing to NZ or
Australia.

The Island Cruising Association are supporting the All Points Rally, from all
major parts of South Pacific to Opua ending in a one-week seminar 16 to 20
November in Opua. Boats joining the rally are assisted with weather info,
resources and planning tools to help make the passage to NZ as easy as possible.
On arrival participants are welcomed to Opua and entertained with a week of
entertainment and seminars on a range of topics. This rally is FREE thanks to
the assistance of Main Sponsors Bay of Islands Marina and Boatyard and the Opua
business community. See www.islandcruising.co.nz/?page_id=717

Further west there is the GO WEST Rally. Again from any port (most are leaving
from Noumea) this time to BUNDABERG, with welcome week starting 6 November 2016.
See www.downunderrally.com/westrallyfee

Travel between Fiji/Tonga and NZ:
The next trough to affect Fiji is expected on 29 /30 Oct an winds should return
to SE on 1 Nov. For Tonga that trough is expected 31 oct/1 Nov wit winds
returning to S/Se on 2 Nov. Avoid departing during this trough.
There are expected to be large slow-moving highs crossing between Tonga/Fiji and
NZ this week, so try and go around the back end of these highs to avoid their
light winds (unless motoring). The highs are NOT expected to be intense enough
to form squash zones between Tonga/Fiji and NZ, but may be some in the Coral
Sea.
Try and avoid arriving at NZ when a trough passes Northern NZ on Tue night/ Wed
1/2 Nov.

Travel between New Caledonia and Brisbane/Bundaberg area:
That weekend surcharge is a factor to consider. As for departing from Noumea,
well there are only light winds forecast for local Monday and Tuesday, so that
makes Wednesday onwards the best days to depart this week. The next trough to
reach Bundaberg is expected on 31 Oct but really that trough is further south,
so that's when Bundaberg may have light variable winds.

Travel from New Caledonia to New South Wales
No real point in taking the rhumb line for such a voyage as the subtropical
ridge should be gone around rather than thru. Instead head for Brisbane, and
around 158E turn to your destination. This should also give you the benefit of
the assistance of the East Aussie current. However, note that there is an active
trough south of 30S on Monday 31 Oct/Tue 1 Nov.
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