El Nino is not only expected to affect monsoon in India but also in neighbouring countries like Sri Lanka, Pakistan, Nepal and some parts of Myanmar.

The 6th session of the South Asian Climate Outlook Forum (SASCOF), a sub-regional body of the World Meteorological Organization (WMO) devoted to specific monsoon predictions and outlook needs of countries with similar climatic characteristics, has made the forecast in its outlook for the southwest monsoon season 2015.

The SASCOF concluded that apart from southern parts of islands, no other part of South Asia is likely to receive above-normal rainfall. The assessment showed central India (including Maharashtra), some parts of northeast India, northwest India and northern parts of peninsula India in the 'below normal' rainfall category.

The forum discussed various observed and emerging climatic features such as the El Nino conditions over the equatorial Pacific, Indian Ocean Dipole (IOD) conditions over the Indian Ocean, winter and spring Northern Hemisphere (NH) snow cover and land surface temperature anomalies among others. All these factors can impact the performance of the southwest monsoon.

As per the outlook, northwest India, central India, northern parts of peninsular India, some parts of northeast India may get below normal rainfall this year. These regions had 'below normal' attributed to them as the 'most likely category'.

The consensus outlook released recently said that since September 2014, the west and central equatorial Pacific has been abnormally warmer. "Sea-surface temperatures in the east equatorial Pacific, which were close to normal or slightly below normal during January to mid-March, have now become above-normal. The equatorial Pacific has now warmed up sufficiently to have reached weak El Nino level. Latest forecasts indicate about a 70% probability for El Nino conditions to persist until the southwest monsoon season," the forecast said.

The document further said that there are chances for El Nino conditions to become stronger during the later period of the monsoon. Experts at the forum felt that El Nino conditions are usually known to weaken the South Asian southwest monsoon circulation and adversely impact rainfall over the region.

The consensus outlook was based on expert assessment of global climate indicators, experimental models as well as experimental as well as operational long-range forecasts based on statistical and dynamical models produced by various operational and research centers of the world.

The forecast was prepared considering the forecast products from various centers from across the globe, including India Meteorological Department (IMD) and city-based Indian Institute of Tropical Meteorology (IITM).
(Times of India)