Bob Blog 25 Dec 2016



Compiled Sun 25 December 2016

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.

Here’s to a peaceful and joyful Christmas and end of the year to you all.

However, there is some activity in the South Pacific and around Australia this week so there are a few potential tropical depressions that may be worth avoiding.

These can be seen on the website, shown here as five L. centres


Map from showing five L centres.

The Tropics

TC NOCK TEN is moving west across the Philippines on Boxing day as a severe tropical cyclone, and may end up near Vietnam coast at turn of the year.


As seen at

Of all those Lows in the Australia/South Pacific area, the one that at present has the most grunt is FORMER TC Yvette , now a monsoonal depression, bringing its rain to South Australia.


As seen at

Rain maps show that activity is on the decrease around Fiji, and on the increase over Philippines, Australia, and Southern Cooks. Also in the Indian Ocean and along the Intertropical Convergence Zone.




Rain for the past fortnight from


Weather Zones (see text) as expected mid-week on Wednesday (GFS model) showing wind, isobars, current, swell black arrows / Sig wave height purple lines, swell and wind waves, SPCZ and STR.


SPCZ=South Pacific Convergence zone.image

SPCZ is drifting south this wee,k and leaving a few smaller convergence zones further north, Expect a tropical Low over Southern cooks to peal around Wednesday UTC, and another near Vanuatu by New year’s weekend. Lows may come and go around Australia all week.


Tropical accumulated rainfall for next week from

Subtropical ridge (STR)

The HIGH n the Tasman Sea tonight is expected to remain slow-moving and drift north to 30S and linger there until early next week

Next High is weaker and should appear over and east of Tasmania early in the New Year.

Tasman Sea/NZ Area troughs.

A disturbed SW flow is likely over northern NZ this week. Next trough of consequence should start arriving over southern NZ on wed, central NZ on Friday and northern NZ over the New year weekend.


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