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

16 November 2008

BOBGRAM7 issued 16 Nov 2008

WEATHERGRAM
YOTREPS
Issued 16 Nov 2008
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.

TROPICS
Some near equatorial westerly winds are appearing in the Indian Ocean
around 5 degrees north-It is too early to tell if this will produce an
east-ward moving surge of activity known as a Madden Julian Oscillation
(MJO)-might do, in which case we will need to watch the Coral Sea
closely in 4 or 5 weeks from now, just before Christmas, for possible TC
activity.

South Pacific convergence Zone SPCZ has reformed in a zone from Solomons
to Wallis/Futuna to Samoa/Northern Tonga. There is still an upper
trough lingering along 25S between NZ and Fiji/ Tonga, with light and
variable winds at sea level to north of this and a band of strong SE
winds on its southern side.

SUBTROPICS
A reliable SE wind is expected to arrive at Minerva on wed 19 Nov and at
Tongatapu on wed/thu 19/20 Nov, good for sailing with to NZ. This
sailing window is brought about by a HIGH crossing NZ on Thu 20 and then
lingering for almost a week just east of NZ. This is the best looking
window we have had so far this month for Tonga to Opua travellers.

TASMAN SEA/NZ
Front is weakening and expected to cross Northland on Monday 17 Nov,
followed by a day or so of southerly winds. Then the weather turns into
a HIGH followed by LOW, with the HIGH crossing the Tasman Sea on 17-19
Nov (good for those sailing from New Caledonia to Brisbane), NZ on Thu
20th, then lingering east of NZ along 40S maintaining a squash zone near
30S.

Large LOW is forecast to form over Victoria and New South Wales on
Wednesday (avoid) and then split into multiple centres as it crosses the
Tasman Sea and southern NZ on Thu to Monday (avoid). The W to SW winds
following the fronts of these lows should reach Northland around Mon
/Tue 24/25 Nov (these can be used for sailing, with care).

The HIGH following this Low is forecast to collapse in the Tasman Sea,
paving the way for another family of LOWS to form in the hot Aussie
interior early next week. This all means unsettled weather in the
Tasman Sea from wed 19 November for maybe 10 days.

I am in Greymouth this week attending MetSoc/hydro Soc conference. Had
scallops and whitebait, followed by a mushroomed T bone and washed down
with Monteiths this evening. Will be back checking email from Sat 22
Nov

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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