Bob McDavitt's ideas for sailing weather around the South pacific

17 March 2019

Bob blog17 March 2019




Compiled Sun 17 March 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.


First, I must tell you all that I (as with the rest of Kiwiland) was shocked and saddened by the senseless killing on Friday in Christchurch. My thoughts are with the victims. I can’t fully concentrate on meteorology when all  this inhumane violence is around, so this week’s blog is a brief one. See Image is from (Thanks to Shaun Yeo)

Give help at ($~4millionNZD already donated)


Second, since my DNA is apparently 95% traceable to Ireland, I can wish you all a Happy Saint Paddy’s day today. Sláinte



The sun is directly over the equator on Wednesday 20 March 2158 UTC (in NZ that’s Thursday morning around 11am NZDT), and that’s the equinox. Australia, New Zealand and Samoa switch from Daylight or Summer time to standard time on 7 April, the first Sunday in April.


World Met Day

Another day worth noting this week is World Met Day on 23 March. This marks the anniversary of the opening of the World Meteorological Organisation as part of the UN in 1950. This year’s theme is THE SUN, THE EARTH AND THE WEATHER

The Sun delivers the energy that powers all life on Earth. It drives the weather, ocean currents and the hydrological cycle.

It shapes our mood and our daily activities. It is the inspiration for music, photography and art.

See  for an enjoyable encounter with nature.



During the past week TC IDAI made land fall over Mozambique and Zimbabwe bringing death and destruction (over 30 deaths during IDAI after a week of at least 66 deaths from floods). Flash floods in Indonesia over last few hours have killed at least 50 people. It is sad but true, that “Weather is the biggest terrorist on this planet”.

Cyclone track from wunderground is at

Note that month should be 3 rather than 4.

Latest cyclone activity as at and TCFP tropical Cyclone Formation Potential as seen at

TC SAVANNAH is over the open sea in South Indian Ocean , and Depression 03W is moving towards Philippines and Depression 92P near Papua New Guinea, is moving toward Queensland.

The MJO (Madden Julian Oscillation) wave of increased activity is travelling east across Northern Australia this week, and so we can anticipate increasing activity in the South Pacific over the next few weeks.

Rain in the past week has intensified around Papua New Guinea and along the Pacific ITCZ west of the dateline. It remains weak elsewhere in the South Pacific.  See

The “mirror CZ” continues just south of the equator in the eastern Pacific, affecting those sailing between Galapagos and Marquesas.



SPCZ=South Pacific Convergence zone.

The SPCZ is active over Papua New Guinea and the northern Coral Sea, with a tropical Low 92P having a good chance of becoming a cyclone as it heads towards northern Queensland. Activity on the SPCZ is also expected to intensify between the Coral sea and Vanuatu this week.

The week starts with a Low on a convergence zone between Niue and Southern cooks. This low is expected to move off to the south and that should weaken the shower activity over French Polynesia.


Subtropical ridge (STR)

HIGH over southern NZ tonight is expected to travel east along 45 South.

The next two HIGHS are also expected to travel south along around 45 to 50S – it’s that time of year that the HIGHS stay south (the equinox).

This fills half the Tasman Sea with easterly winds good only for sailing west.


Australia/Tasman Sea / New Zealand

The western half of the Tasman Sea is expected to be dominated by a trough this week—with variable winds and some rain, also with northerly winds on its eastern side, good for sailing.


Panama to Marquesas

There has recently been a NE blast across Panama and winds/waves are expected to be uncomfortably high for departure until Tuesday, and it may get uncomfortable again from Thursday to Saturday this week. Looking easier next week.

There is a good tail current to north end of Galapagos, then go to 6S 100W, to avoid the building “mirror convergence zone” along around 5 South,


Port Vallarta to Marquesas

There is a Tejuantepecer blast occurring this week and another expected at the end of March (for background see However, winds around Puerto Vallarta are likely to be OK for departure anytime this week.

Weak ITCZ likely between 6N and 3N, and then a “mirror CZ” near 3 to 5S



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