Weathergram 7 Oct 2012

Issued 7 Oct 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.

Just a brief weathergram this week…there will be more to write about next week.

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 near zero for the past week. It’s now in neutral mode, and is likely to swing back into El Nino mode over the next few weeks.

The South Pacific Convergence Zone SPCZ remains active from the Coral Sea across northern Vanuatu and occasionally to Fiji, with another branch from Kiribati to Tuvalu to Tokelau across Northern Cooks towards Marquesas. The section that has recently been visiting Fiji and Tonga is expected to take a breather this week. The section over the northern Coral Sea may develop a tropical low near the Solomons on Monday and again next Saturday 13 Oct.

High HI that briefly crossed the North Island today Sunday is expected to move steadily east along 25 to 35South getting to south of French Polynesia longitudes by Wed 10 Oct , producing a squash zone of enhanced trade winds on its northern side.

Next High H2 is expected to be over New South Wales on Monday and then weaken as it crosses the Tasman Sea and the North Island on wed 10 Oct and then spread east from NZ between 30 and 35S from Thu 11 Oct top Sun 14 Oct. By which time another High is likely to be over New South Wales. At present there seems to be a rhythm in these highs.

NZ/Tasman Sea
Between the passing Highs, NZ continues to be subjected to a disturbed westerly flow, with LOWS forming and deepening in the mid-Tasman Seas on Monday and Tuesday 8-9 Oct and again on Friday to Sunday 12-14 Oct.
This next ‘window” of OK conditions for approaching NZ from the north, at this stage, is Wed 10 to Fri 12 and again from Mon 15th to Thu 18 October.

If you are planning to sail from Tonga/Fiji/Vanuatu/ New Caledonia to NZ in October/ November, and looking to buddy with someone, then you may be interested in checking out the ICA’s “All Points Rally” to Opua, see .

And if you are heading for NZ from Tonga then you may like to know that vessels on this route have recently been reporting PUMICE near the Kermadecs. No one has reported any problems with this pumice so far.

See my yotpak at for terms used.
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