El Nino has set in, the latest update from the European weather agency indicated on Thursday. According to it, temperatures in the rapidly warming Pacific Ocean crossed the 0.5°C threshold of El Nino in May. This is likely to set in motion changes in atmospheric conditions that are projected to deeply impact global weather – including the Indian monsoon – in coming months.The release from European Centre for Medium-Range Weather Forecasts (ECMWF) is the first update in June from a major global weather agency on the state of the Pacific Ocean. Most agencies had said last month that El Nino was on the verge of setting in, with US govt institutions putting the probability of it forming in May-July period at 82%.
“The latest chart from ECMWF shows that the 0.5-degree threshold has been crossed. Officially, an El Nino event will be declared only when these changes persist for at least three months. But that’s of academic interest. Changes in the atmosphere associated with an El Nino are already being seen and its impact being felt,” said M Rajeevan, veteran meteorologist and former secretary of the earth sciences ministry. The ECMWF update came on the day the monsoon arrived over the Indian mainland (Kerala), three days later than its normal date of June 1. IMD chief Mrutyunjay Mohapatra said the monsoon is likely to march into more parts of the western coast and Karnataka, move into Andhra and cover TN in the next two-three days. “The intensity of rainfall in these areas is not likely to be high,” he said.As for El Nino setting in, Mohapatra said updates from other agencies should be awaited to get a clearer picture. US govt agencies and IMD are likely to release their forecasts within a week or so. IMD has forecast below-normal monsoon this year at 90% of the long period average, bordering on ‘deficient’ (below 90%). The Australian weather bureau had late last month stated that the warming in the region known as Nino 3.4 – the area in mid-east equatorial Pacific most often tracked for El Nino – was 0.67 °C above normal. This is above the 0.5°C threshold most agencies use for the onset of El Nino. The Australian bureau’s criterion is 0.8°C.According to the latest ECMWF seasonal forecast, temperatures at the end of May crossed 1°C above normal in the Nino 3.4 region.
