US weather agency CPC lowers La Nina chances in July-September a tad

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The US weather agency Climate Prediction Center (CPC) has lowered the chance of the La Nina weather phenomenon, which leads to heavy rains and floods in India, emerging during July-September 2024 to 65 per cent from 69 per cent a month ago.  However, it maintained that there is an 85 per cent chance that La Nina will persist into the Northern Hemisphere winter of 2024-25. 

This is because the forecast team of CPC, an arm of the National Oceanic and Atmospheric Administration, has found the rate of cooling has slowed since May. However, it still favours the development of La Nina during July-September 2024.  

“The team still favours La Niña to emerge sometime during the summer months, given the persistent below-average subsurface ocean temperatures and changes in the tropical atmospheric circulation,” it said in its “Final El Nino Advisory and La Nina Watch” on Thursday. 

ENSO-neutral

The US weather agency also confirmed the end of El Nino, which led to drought in many parts of Asia, including India where 25 per cent of the country was hit by drought. “ENSO (El Nino-Southern Oscillation)-neutral conditions are present… ENSO-neutral conditions returned during the past month,” it said.  

CPC’s El Nino predictions are in line with Australia’s Bureau of Meteorology’s forecast that found four of 7 models suggest SSTs (sea surface temperatures) are likely to remain at neutral ENSO levels, with the remaining 3 models showing the possibility of SSTs cooling to La Niña levels from August.

The Australian weather agency said La Nina may emerge in late 2024. In April, it said El Nino had ended.  

Meanwhile, the Bureau of Meteorology said the Indian Ocean Dipole (IOD) is currently neutral. The most recent 6 weeks have seen the IOD index within neutral thresholds, with the latest weekly value close to zero.