Global weather models indicate delayed emergence of La Nina

While El Nino is known to suppress the monsoon rainfall, La Nina positively influences and enhances the rainfall over India during the Southwest Monsoon season. Earlier this year, the India Meteorological Department (IMD) said the emergence of La Nina during the latter half of the monsoon season could bring above-normal rainfall over the country. This season, the Met Department has forecast 106 per cent of the Long Period Average rainfall over the country.

According to the National Oceanic and Atmospheric Administration (NOAA), a delayed emergence of La Nina is favoured. In its ENSO update on July 11, the US-based agency said the emergence of La Nina is likely from September to November. Once La Nina conditions develop, they would prevail through the winter season of the northern hemisphere. A transition from neutral to positive sea surface temperature indicating ENSO neutral towards La Nina was likely to take place during August-October, the forecast said.

The Bureau of Meteorology (BoM), Australia, too, has maintained the La Nina ‘watch’ stage. In its latest ENSO outlook, the Australian agency said the cooler-than-usual sea surface conditions along the equatorial Pacific Ocean were likely to emerge towards the latter half of this year. The Bureau also said the global sea surface temperatures were at a record high during April-June this year.

In its outlook issued on July 5, the Indian National Centre for Ocean Information Services (INCOIS), Hyderabad, said ENSO neutral conditions would prevail until September this year only after which chances of La Nina were likely. “The development of La Nina is high in September-January. It could peak during November this year,” the INCOIS outlook stated.