Bob Blog 29 Sep



Compiled Sun 29 September 2019

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 latest cyclone activity report is at and TCFP tropical Cyclone Formation Potential at

At present there are three active Cyclones LORENZA in the mid north Atlantic, NARDA heading for Baja California and MITAG near Japan, and a few areas of potential activity in North Pacific. ‘Looks like we are heading for a lull in the cyclone season.




Weather Zones (see text) as expected Wednesday 00UTC showing isobars, winds, waves(magenta) STR, and SPCZ. Pink area = lightning likely (high CAPE)

SPCZ=South Pacific Convergence zone.

The SPCZ is expected to stretch from Solomon Islands to Tuvalu /Tokelau, similar to last week.

Passing trough 1012-16hPa over Tonga on Tongan Tuesday, Palmerston on Local Wednesday, and Southern Cooks and parts of Tahiti on local Thursday/Friday followed by SE winds.

Heads up that a bigger passing trough 1008-1012 hPa is expected the following week.


Accumulated rainfall for next week from

Subtropical ridge (STR)

The STR has retreated to 30S around NZ

HIGH to NE of NZ on Monday travelling east along 30S around 1024, so no squash zone.

Next HIGH forming in Tasman Sea by Tuesday travelling NE to 30S by Friday the fading but followed by another HIGH on Friday/Saturday.

Tasman Sea /NZ/Aus

Intense Trough over northern NZ on local Monday, followed by a SW/WSW flow until Thursday. swell until Friday, strong on Wednesday, easing by weekend.

HIGH in N Tasman Sea should ridge towards northern NZ on Thursday/Friday.

Another Front is expected over Southern NZ on Friday and central/northern NZ by Saturday, followed by a southerly flow.

Reasonable for voyages from tropics to NZ departing this week. Voyage will need waypoints.

For Noumea to Aus: S to SSE winds at Noumea on local Monday Tuesday in wake of a passing trough then SE winds expected from Wednesday onwards , Ok for going to Aus,.

Tahiti to Tonga

The passing trough 1012=1016hpa later in the week doesn’t really have much wind swing at the surface, so can depart any date this week with mainly trade winds.

However a deeper trough 1008-1012hpa is expected to reach Tonga around Sunday 6 oct followed by SE winds, and then travel east, so may need to arrange some positioning waypoints for that.


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