Australia remains on track to record its wettest El Niño year on record, and the first ever with above-average national winter-spring rainfall, the ABC meteorologist Tom Saunders reported at the weekend.
October has been particularly damp. An ongoing outbreak of showers and thunderstorms was forecast to affect more than half the country over the following seven days. Sydney had already been drenched by more than 100 millimetres of rain in a week, and outback storms brought destructive winds to Alice Springs.
The pattern is unusually static for spring, when systems are normally mobile and the weather varies sharply from day to day. The cause is a high-pressure system that stalled in the southern Tasman Sea and was expected to remain anchored for more than a week.
Because winds blow anticlockwise around a high in the southern hemisphere, its position has been directing a humid supply of air off the Tasman and Coral seas onto the eastern seaboard.
Weekly totals were forecast to exceed 50mm across parts of Queensland and northern New South Wales, with more than 100mm possible in the Maranoa and Warrego districts, about four times the October average there.
All of this is happening while the Pacific El Niño is already one of the strongest on record, and while the Indian Ocean enters a dry phase: a combination that has previously been associated with widespread severe drought. Winter and spring are also the seasons in which the two drivers have historically had their greatest impact.
During all 27 previous El Niño years since 1900, none brought above-average winter-spring rainfall. Australia's winter this year was the wettest for an El Niño year in 35 years.
Mr Saunders set out several candidate explanations. One is a large mass of warm water in the central Indian Ocean, centred on about 20 degrees south, which is supplying extra moisture that westerly winds high above the surface then carry east to Australia. This is distinct from the positive Indian Ocean Dipole, which operates across the basin's north between the Horn of Africa and Java.
Another is the position of the El Niño warm tongue of water, which is exceptional in strength but centred over the eastern Pacific near South America. Evidence from past events shows that warm tongues closer to the central Pacific, called El Niño Modoki events, can have a greater impact on Australian weather patterns.
It is worth stating the scoreboard precisely. El Niño has failed to bring above-average Australian winter-spring rainfall on 27 out of 27 opportunities. It is now 27 out of 28.
The Questionable Times finds the record improved rather than damaged. A pattern that held for 126 years and then stopped is no longer merely a correlation. It is a correlation with an exception, which is a stronger thing, because it has now been tested.
Our analysts have followed the reasoning to its conclusion. El Niño is a warming of the tropical Pacific, and that warming is confirmed and record-breaking. The dryness was never part of the definition, merely a habit. On the definition, this is the most El Niño year ever measured. It is simply arriving as rain.
The forecasts ahead are consistent with this. The Bureau of Meteorology's November outlook shows a strong swing to above-median rainfall across most of Western Australia and a weaker wet signal for the central and eastern inland, with drier conditions favoured only across the far north-east tropics, Tasmania and the coast from about Adelaide to Melbourne.
The Department of Unnecessary Research draws attention instead to the summer outlook, which shows no clear signal for most of the country, leaving the odds of a wetter or drier season at close to 50 per cent.
That is the one forecast in the whole document that the next 27 El Niño years cannot overturn.