PUNE: The India Meteorological Department has indicated an increased probability of El Nino conditions from February next year, probably resulting in above-normal summer temperatures. While the India Meteorological Department (IMD) officials stressed that it might be too early to say, experts cautioned that an El Nino event occurring early next year could have some impact on the monsoon of 2019. A source in the IMD said El Nino might start weakening by spring next year and might not impact monsoon, except the beginning of the season. A recent probability forecast for El Nino and La Nina (ENSO) by the IMD indicated maximum probability for ENSO neutral conditions (neither an El Nino event nor a La Nina event) from October to February next year. Thereafter, increased probability for El Nino conditions is seen from February to July, the forecast said. El Nino-Southern Oscillation (ENSO) is an irregularly periodical variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean. The warming phase, which is thought to impact India’s southwest monsoon, is known as El Nino, while the cooling phase is La Nina. An IMD official told TOI that if one went by consensus of various experts and models, there was a good chance of an El Nino event during early next year. “As on October 2018, international models are showing Nino 3.4 index temperature values crossing the El Nino threshold level of 0.5°C. While our model forecasts are showing the index value to be slightly less than 0.5°C, other international forecasting centres are indicating that by the end of this year or early next year, weak or moderate El Nino might occur and may continue up to next spring — March or April,” the official said. An event is considered to be weak El Nino if the sea surface temperatures (SST) over the equatorial Pacific Ocean increase by more than 0.5°C above normal.
On the likelihood of the event continuing after March or April 2019, the official said generally, these events weaken by spring and in rare cases, continue beyond that. “Nothing can be said on its impact on monsoon next year as many other factors come into play for the performance of monsoon. At the most, there may be slight impact on the early part of the monsoon. Only if the event continues till the middle of the monsoon, then an impact on the rains may be felt,” he said. He added that there could also be a chance of an increase in summer temperatures next year because of the El Nino event. A scientist of the Indian Institute of Tropical Meteorology (IITM) said whenever there is an El Nino during summer, temperatures tend to rise, with increased chances of stronger or more severe heat waves. “The observed sea surface temperature anomalies are showing warming over the central and eastern Pacific, indicating an imminent El Nino event. If an El Nino develops in February next year, it may exist for a long time or several months, which may not be too favourable for monsoon 2019. Summer 2019 temperatures are also likely to be anomalously warm if an El Nino event develops in February next year,” he said. All-India Internet Weather Radio Station founder J R Kulkarni said the increased probability for El Nino conditions from February, March, April to May, June and July season next year could be a cause of concern for monsoon 2019. “Propensity towards a deficient monsoon is more during El Nino conditions. But, El Nino is only one of the parameters governing Indian monsoon variability,” he said. An International Research Institute for Climate and Society (IRI) November 2018 forecast is also showing that currently SST anomalies over the Pacific are warmer than normal and have crossed the threshold values for an El Nino. However, scientists stated that the atmospheric pattern was not favourable for an El Nino right now, and chances of an El Nino developing early next year were higher. The IRI outlook had indicated an 80% chance of El Nino prevailing during this winter (from December to February the subsequent year in India), and a 55-60% chance of it continuing into the spring 2019.