Weathergram

WEATHERGRAM

YOTREPS

Issued 4 Nov 2012

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 of weather maps, so please fine-tune to your place. Dates are in UTC unless otherwise stated.

The Atmosphere: The Southern Oscillation Index or SOI (30 day running mean) is relaxing after a bounce back from its low of -1.01 back on 25 Aug. It has been hovering around plus 0.2 to 0.3 during October, and was 0.4 on 4 November. It’s now in neutral mode.

Tropical cyclones in the Northern Hemisphere have quietened down since SON-TINH and SANDY. There is a tropical depression between Mexico and Hawaii called ROSA but it is just likely to go west and fade.

South Pacific Convergence Zone SPCZ

The South Pacific Convergence Zone SPCZ has slowly intensified during the past week and is mainly stretching from Solomons to northern Vanuatu to north of Fiji, with another clump along 10S between Northern Cooks and Marquesas.

Late Tuesday a tropical low is likely to form near Fiji and then deepen rapidly and move southeast across southern Tonga/Minerva possibly with gales and then go off the SSE. Avoid. It might earn itself a name as cyclone number 1 for the South Pacific season 2012/13.

SUBTROPICAL RIDGE STR

The new high crossing the Tasman One today should be held in place aloft and take all week to cross New Zealand. This offers a good opportunity to anyone wanting to sail to NZ – but those sailing from Tonga should already have left in order to escape the Wednesday Low.

image

Mid week weather map

NZ/Tasman Sea

Low is expected to form off Sydney on Friday 9 November and its trough should cross NZ on Monday/Tuesday 12/13 Nov.

SAILING TO NORTHERN NZ.

This week is probably the busiest of the year foe NZ arrivals, and we are having a high, so that’s good.

The hard weather is at your departure zone. If you are in Tonga you’ll now need to wait for that Wednesday low to blow through and the swells to settle again, maybe 10 November, so not this week. If you are in Brisbane the easterly winds are against you. If you are in New Caledonia then time your departure to make best use of the SW winds following the low crossing NZ on 12/13 November. If you are in Fiji there are many options.

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One thing that sailors heading for New Zealand over the next week or two may want to consider is the total solar eclipse on the new moon on 14 November. Its track is roughly WNW to ESE on a line north of NZ. Timing your voyage to catch is will be complicated, but imagine the kudos.

For more info http://eclipse.gsfc.nasa.gov/OH/OH2012.html#SE2012Nov13T

Here’s the map(click to enlarge)

image

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See my yotpak at http://www.boatbooks.co.nz/weather.html for terms used.

Weathergram with graphics is at https://metbob.wordpress.com/

Weathergram text only http://weathergram.blogspot.co.nz

Website http://www.metbob.com

Feedback to bob@metbob.com

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Published by metbob

Pattern and Chaos

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