Bob blog 10 Oct

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.

Compiled Sunday 10 October 2021

Bureau of Meteorology outlook for coming cyclone season around Australia



Recently ENSO has been neutral. Models are now indicating a 67% to 87% chance of a LA NINA episode from Nov 2021 to Jan 2022neutral conditions. La Nina typically results in increased cyclone activity in Australia and in the South Pacific west of the dateline.

In spite of this, the Long-Range Tropical Cyclone Outlook for Australia (TCO-AU) suggests near-normal cyclone activity around Australia for the Nov 2021 to April 2022 period, with between 8 and 13 cyclones.



The latest cyclone activity report is at and Tropical Cyclone Potential is from


There are still some areas of high potential for formation around Philippines. TC LIONROCK has been crossing the China Sea and my make landfall onto north part of vietnam.


Weather Zones Mid-week GFS model showing isobars, winds, waves(magenta), Rain (Blue),

STR (Subtropical Ridge), SPCZ (South Pacific Convergence Zone) and CAPE (in pink)


CAPE mid-week as seen by ECMWF and GFS from


SPCZ=South Pacific Convergence zone.

The SPCZ is less active but more spread out than last week.

Active trough between Fiji and Samoa on local Monday is expected reach Southern Cooks by local Tuesday with Low L1 near 25S and this then moves off to the southeast leaving a large lull in its wake.


Rain Accumulation next five days from


High1 north of NZ on Monday is expected to travel northeast to 25S and then east maintaining a lull in the wake of L1.

Low L2 is expected to form south of NZ in a trough crossing the South Island on Monday and then deepen to 980 east of South Island on Tuesday/Wednesday feeding polar chilled southerly winds onto NZ, then moving off to the east.

High H2 should follow L2 and then travel NE of NZ by Saturday, providing good conditions for arriving in Opua early next week.

Low L3 is expected to travel east across Bass Strait and into the southern Tasman by the end of the week.


If you would like more detail for your voyage, then check to see what I offer.

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Published by metbob

Pattern and Chaos

Join the Conversation


  1. Hello Bob, John Newcomb from Nirvana 1 here (last a client in 2017). We are thinking of leaving Mackay for Moreton Bay anytime from this coming Monday. May I request your usual service for advice on departure timing and route planning? We are not in a rush and will definitely stop in for “rest and recreation” between Percy Islands and Lady Musgrave reef inclusive and then go outside Fraser Island. Cheers John 0414 948 885

    1. Hi there John. I don’t usually issue advice for coastal trips. For One, the global weather models I have access to do not have good enough resolution for coastal sailing, and for two, the Bureau already issues coastal forecasts free of charge and available on marine radio , etc updated several times a day with outlook 3 days ahead issued by a team of experts watching high resolution models and weather radar.
      All I can do is relay this and charge you for the time it takes me .
      Having explained all that, I’m willing to share a quick look for you: There are tail winds or starters from Mackay next few days = good to go, but these fade on Friday.
      Maybe a passing trough over the weekend and then NE to SE winds next week = no good.
      These SE winds may strong mid to late next week off Fraser island as a low is likely to form offshore.

      Let me know if you would like me to email a quick review of this on Saturday?

      Bob McDavitt

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