El Nino has set in, Positive IOD likely by July, says Japanese weather body

Drought-bearing El Nino has set in, while a positive IOD will emerge by July (boreal summer), the Japanese weather agency JAMSTEC has said.

“As predicted earlier, an El Nino occurred,” JAMSTEC said Thursday, thus becoming the first agency to declare the arrival of the climatic pattern.

JAMSTEC’s predictive model, SINTEX-F, forecasts a further development of El Nino towards a strong El Nino in boreal summer, between June and August. A few members of the ensemble are forecasting a “super” El Nino late in 2026.

SINTEX-F (Scale Interaction Experiment-Frontier) is a coupled ocean-atmosphere climate prediction system developed by JAMSTEC in collaboration with European partners.

The tropical Indian Ocean is currently in a neutral state, SINTEX-F said. The model predicts a positive Indian Ocean Dipole (IOD) event in the boreal midsummer (July).

​A positive IOD can bring more moisture to India, often helping monsoon rains even in an El Nino year. IOD is a climate phenomenon caused by variations in sea temperatures in the Indian Ocean. Its positive, negative and neutral phases can influence the Indian monsoon.

The development comes on the heels of the India Meteorological Department (IMD) lowering its forecast for the South-West Monsoon to receive 90 per cent of the long-period average rainfall. The monsoon has arrived 3 days late this year on the Kerala coast on June 4.

The model predicts hotter-than-normal conditions for much of the globe during the July–September average.

Relatively high signal-to-noise ratios are observed in the western United States, Mexico, Central America, most of South America (excluding Argentina and southern Chile), New Zealand, southern and western Australia, most of Africa, most of the Middle East, some parts of Europe, Turkey, Indonesia, Papua New Guinea, many islands in the tropical Pacific, most of Southeast Asia, India, Mongolia, some of China, and Hawaii, the report added.

Meteorologists use the signal-to-noise ratio (SNR) to help them determine how much of the data they get from the atmosphere is signal (good information) and how much is noise (random background interference). If the SNR is high, it means the real weather trend is obvious

The report said southwestern Polynesia will be cooler-than-normal. The model shows above-normal temperatures for much of the globe during the boreal autumn (October).

Drier-than-normal conditions are forecast across Central America, the Caribbean, western Brazil, eastern Australia, parts of East Africa, parts of western equatorial Africa, Yemen, Nepal, North India, Malaysia, Indonesia and some islands in the southern tropical Pacific during July–September.