Bob Blog 23 Jan

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 23 January 2022

Some interesting weather clips on you tube this week:

Snow in the Sahara:

Waves in Sc clouds:




Here is last Friday’s Sea surface temperature anomaly SSTA map, showing the cool zone over eastern equatorial pacific which manifests LA NINA.

I have noticed over the last decade or so that SSTA maps have been showing larger areas that are warmer-than-normal than are cooler-than-normal. I understand that the oceans have been warming up because of climate change. On sunny and windless days in anticyclones the surface of the sea can absorb heat directly from incoming sunshine. It also should lose heat to outer space at night, but now there seems to be a imbalance in this. The amount of carbon dioxide in the air has been increasing and this seems to allow the oceans to store more heat.

By definition it takes one calorie to warm a gram of water (at 25C) by one degree, or the thermal capacity of water is 1000 cal/Kg/K, or 4183J/Kg/K. So water “holds warmth” over 4 times better than air (which has a thermal capacity 1004J/Kg/K).

I’ve recently come across a paper in Advances in Atmospheric Sciences, Jan 2022 entitled: Another Record: Ocean Warming Conditions through 2021 despite La Nina Conditions. Creative commons license

It contains this diagram which tracks the amount of heat stored in the oceans since 1960 , compared with a baseline using the 1981-2010 epoch. :


This diagram shows ocean heat content was static until the late 1980s and since then has been rising at a rate of between 8 and 9 Zettajoules per year ZJ/yr. A Zettajoule is 1 followed by 21 zeros. The 2021 annual ocean heat content is a new record and higher than the previous year by around 15 ZJ. So the ocean now contains around 240 ZJ more than the 1981-2010 average. To put this into perspective, the current oil consumption on this planet is 0.2ZJ per year, and electricity generation is 0.1ZJ/year.



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


There are zones of potential formation around Northwest and North Australia and the Philippines and dotted over the South Pacific.


Weather Zones Mid-week GFS model showing isobars, winds, waves(magenta), Rain (Blue),

STR (Subtropical Ridge), SPCZ (South Pacific Convergence Zone) and CAPE (in pink)


CAPE mid-week as seen by ECMWF and GFS from, with vastly different ideas this week


SPCZ=South Pacific Convergence zone.

The SPCZ remains active from Solomons to Vanuatu/Samoa to Southern Cooks.


Rain Accumulation next five days from


Subtropical Low L1 south of New Caledonia is expected to do a loop on Monday and then travel slowly east and fade.

It should trigger a secondary Low L2 west of Taranaki by Tuesday night that is expected to travel SE over central NZ bringing some much needed rain.

Meanwhile tropical low L3 south of Southern Cooks is expected to move off to the Southeast from mid-week after bringing wind and rain last few days to Southern Cooks.

Low L4 is expected to deepen over Vanuatu by Friday and may visit New Caledonia by the weekend, and this may bring strong NE winds to Northland area next week. Avoid.


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