NEW DELHI: The risk of overall monsoon rainfall being ‘below normal’ continues to loom over India due to a strengthening El Niño, but World Meteorological Organisation’s (WMO) latest monthly global seasonal climate update, released late Friday night, offered a ray of hope. It predicted the possibility of a “positive” Indian Ocean Dipole (IOD), which could offset to an extent the negative impact of El Niño.El Niño is a climatic pattern of warming of surface waters of central and eastern tropical Pacific Ocean and is associated with a weak monsoon and harsher summer in India. IOD, on the other hand, has to do with the difference in sea surface temperatures between western and eastern parts of tropical Indian Ocean. It helps in formation of stronger monsoon winds.“A positive IOD is expected to develop… Combined with exceptionally warm global oceans and the likelihood of a positive IOD, the developing El Niño is expected to shape weather patterns across many parts of the world in the months ahead,” WMO said.
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If WMO’s forecast comes true, there is a possibility of improved rainfall conditions in south peninsular India — the region which had reported a high cumulative rainfall deficit of 22% as of Aug 1 — in particular and over many parts of the country in general. Monsoon may avoid deficient phase with positive IODIt may prevent India from slipping from ‘below normal’ phase to ‘deficient’ monsoon phase at the end of the rainy season.El Niño Southern Oscillation (ENSO) and IOD are two key factors that govern variation in monsoon rainfall. Though IMD Friday flagged the continuation of “neutral” IOD conditions through the remaining period of southwest (summer) monsoon, it, at the same time, referred to climate forecasts from some international forecasting centres suggesting that positive IOD conditions are likely to develop during Sept.
