Bob Blog 12 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 12 Mar 2023


Recently there has been a twinning of Lows north and south of Galapagos:


AS seen here today on with L1 near 5N and L2 near 10S. L2 is the remains of Cyclone YAKU that formed a few days ago on that convergence zone that was south of Galapagos as mentioned in my blog over the past few weeks.

Consequently, we have a belt of near equatorial winds just south of Galapagos as shown by the purple arrow, and the trade winds have weakened, and in places reversed for those planning to voyage from Panama to Marquesas, normally done at this time of the year.

There is now a strong movement of sun-warmed surface water eastwards, over 3knots in places around Galapagos.


And this is now starting to pile warmer than normal water along the Peru Coast. One of the yachts that passed thru this area yesterday described the scene thus: “as far as the sea life is concerned, a couple of dolphin came by a day or so ago, few birds resting on the deck at night, and that’s about as much as we have seen, had 3 fishing rods out with various types of lures and not had a touch in 4 days I think they know not to come near this part of the ocean.”


SO much warm water has shifted that the Intertropical convergence zone ITCZ has gone inland and there is now a lot of convective activity along the Peru coast. Parts of Peru have had flooding and mudslides in the past week, see – they have had rain amounts they haven’t seen since Jan 2017 the start of an EL NINO COSTERO event (see


A snapshot of the clouds over the Pacific also shows how the tropical moisture that normally forms the ITCZ has been diverted by strong winds aloft from east of Hawaii to California… an atmospheric river.

Here is a link to a YouTube clip giving an animated loop of the isobars and streamlines in the South Pacific for February 2023


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


Cyclone FREDDY continues to continue and to break records. It has a central pressure around 980 and has made landfall for a second time over Mozambique today. It was named on 5 Feb and is now the longest lasting tropical storm with the greatest ACE accumulated cyclone energy.

A good summary of FREDDY (so far ) has been made by South African meteorologist Annette Botha at

Cyclone YAKU briefly formed off Peru.

There is still a likelihood of low pressure development around Vanuatu this week.

The next MJO is expected to start forming in the Indian Ocean during the next few weeks and, with a lot of hand-waving, if this season’s rhythm continues that means it may reach northern Australia around start or April. So, there is still time for another cyclone to form in the Pacific before the send of the season


Weather Zones Mid-week GFS model showing isobars, winds, waves (purple), rain (red), MT (Monsoonal trough), STR (Subtropical Ridge), SPCZ (South Pacific Convergence Zone) CZ (Convergence Zone) and CAPE (lime)


CAPE maps mid-week GFS and EC from Predictwind, showing chance of lightning.


Rain Accumulation next five days from


The SPCZ is expected to remain active from Solomons to Fiji and in a weaker zone across Southern Cooks and Austral Islands . Several small lows are forming on these zones. A small low 10F near Southern Cooks and another 11F between Fiji and Tonga may have strong winds next few days. but then fade. A more intense low L2 now near Vanuatu is expected to travel slowly south towards New Caledonia and might deepen. A smaller convergence zone is expected to form over the Tuamotu Islands.


A trough is crossing NZ on Monday followed by large High H! crossing the Tasman sea reaching NZ on Tue/Wed, then moving off to the east along 35 to 40S.

Low L1 tonight over Lord Howe island is expected to cross Aotearoa NZ on Thurs/Friday followed by a strong westerly flow.

Those planning to cross the Tasman Sea this week should avoid L1.


If you would like more detail for your voyage, then check to see what I offer.

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Weathergram archive (with translator) is at

Contact is or txt 64 277762212



Published by metbob

Pattern and Chaos

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