Bob Blog 22 Jan 2017



Compiled Sun 22 January 2017

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.

The Tropics are still having a quiet period between active cyclones.

Rather unusual for the to be so quiet for so long…NASA has noticed this anomaly and is Facebooking about it at

My theory, as far as South Pacific is concerned is that the recent temperature anomaly between (hotter than normal) Australia and (colder than normal ) NZ has been producing more westerly winds, knocking the subtropical ridge north of normal , and thus weakening the SPCZ. We had those two deep low across NZ as mentioned in last week’s weather gram, and I think this means the subtropical ridge is now about to be able to shift south onto central/southern NZ during next few weeks.

Rain maps show that an active low affected the area south of Southern cooks and French Polynesia last week, and changes elsewhere were minimal.



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, SPCZ and STR.

SPCZ=South Pacific Convergence zone.

SPCZ remains about the sam etis week as last week, expect for noticable activity in the Fij/Tonga/Niue area culminating in development of a tropcial low soith of Niue at 25S by en of the week. That low is expected to travel slowly south next week .


Tropical accumulated rainfall for next week from

Subtropical ridge (STR)

High in central Tasman sea on Monday is expected to fade over northern NZ by Wednesday.

A new High is expected to spread into the south Tasman Sea on Thursday, and cross central/northern NZ area on Sunday 29 Jan.


Tasman Sea/NZ Area troughs.

A deep low is expected to move off to southeast of NZ on Monday (23rd Jan)

A front is expected to cross South Island on Tuesday and North Island on Wednesday.

Another front is expected to cross South Island on Sunday and North Island on Monday 30 Jan. This is Auckland Anniversary day, so anticipate a change around then to SW 20 gust 30 knots.


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Published by metbob

Pattern and Chaos

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