The Bureau of Meteorology (BoM) has upgraded its El Niño−Southern Oscillation (ENSO) outlook from “inactive” to “El Nino Watch,” which means there is a 50% chance of El Nino developing this spring – this despite the ENSO remaining neutral.

According to the weather bureau, ocean indicators are currently neutral but show signs of potential El Nino development.

“Sea surface temperatures in the eastern Pacific Ocean, though currently neutral, have been slowly warming since April, while waters below the surface of the tropical Pacific are now warmer than average, a common precursor to El Niño events,” BoM said.

Majority of international climate models surveyed by the bureau suggest that the tropical Pacific Ocean will continue to warm but remain in the neutral range during July and August.

"Five out of eight models indicate that the ocean warmth is likely to reach El Niño thresholds in the southern hemisphere spring, while a sixth model falls just short," said Robyn Duell, the bureau's acting manager of long range forecasting services.

During El Niño, eastern Australia typically experiences below-average rainfall during winter and spring. A neutral ENSO phase has little effect on Australian climate.

Meanwhile, five out of six climate models indicate that the Indian Ocean Dipole (IOD) – another of Australia's key climate drivers – will likely remain neutral in the coming months and one model suggests a positive IOD.

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