Bob Blog 29 March

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 29 March

More on the Australian Flood

There was a blocking HIGH in the South Tasman Sea, and it took several days for a Low to form over NW Australia and the finally travel southeast across Australia and kick that HIGH away. This meant that there was a squash zone of strong steady onshore winds onto the Australian East Coast, bringing rain that showed up on the weather radar from Bundaberg to Melbourne for days.


One way of looking at this weather pattern is to plot a tome-latitude plot of the zonal winds along the 145 to 155E longitude band (basically the Australian east coast) as can be done at from 14March to 26 March. In this diagram the blue-purple-white shaded areas are the on-shore easterly winds, peaking from 20 to 24 March.


And a grab from shows that as I write this the container ship EVER GIVEN is still stuck in the Suez Canal:


And here is some GOOD news: Fiji have agreed to extend their Blue Lane entry permission to Savusavu from 1 April, see

The Tropics

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

It is another quiet weekend with no active cyclones.



Weather Zones Mid-week GFS model showing isobars, winds, waves(magenta), Rain (Blue), STR (Subtropical Ridge), and SPCZ (South Pacific Convergence Zone).


Predict wind CAPE mid-week gives two possibilities for SPCZ.


SPCZ=South Pacific Convergence zone.

SPCZ is rather broad and weak, stretching from Coral Sea/Solomons to Fiji/ Samoa with some convergence zones around French Polynesia.

Weak passing trough over New Caledonia on Tuesday 30 March.

Low is expected to form in the Coral sea by sat 3 April and should stay SW of New Caledonia.

Lows are also expected to form near Austral Islands and south of Pitcairn at end of the week, travelling off to the east.


Rain Accumulation next five days from

Subtropical ridge (STR)

HIGH east of NZ is expected to travel off to the east along 40S.

New High is expected to travel into Tasman Sea from New South Wales on Wednesday and reach northern NZ for the Easter weekend.

Aussie/Tasman/NZ troughs

Trough over central NZ tonight crossing North Island on Monday/Tuesday, -stay put.

Low is expected to form in south Tasman Sea on Monday and travel east over central NZ on Wednesday, followed by a southerly flow on Thursday/Friday.

Panama to Galapagos/Marquesas

Moderate northerly to NE/E winds to Galapagos this week, along with a good tail current. .

. Path to take to Marquesas this week is via NORTH of Galapagos.


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