The latest joint update issued by US agencies under the country’s National Atmospheric and Oceanic Administration (NOAA) gives an 82% probability of an El Nino developing in the May-June-July period, up from 62% in the previous month’s forecast. If the forecast is accurate, most of this year’s monsoon will play out in the backdrop of a growing El Nino event. The forecast says there is a 90% chance of the weather phenomenon persisting into the winter.
El Nino is a condition of abnormal heating of the ocean surface in east and central equatorial Pacific leading to changes in wind patterns that impact weather. El Nino and La Nina – the opposite of El Nino – are significant drivers of summer monsoon rains in India. In the last 50 years, all drought years in India have coincided with El Nino. However, not all El Nino events have led to deficient monsoons.
As per the latest NOAA update, there’s a 63% chance of the El Nino strengthening into a moderate event by July-August-September and a 53% probability of a strong El Nino developing by October-November-December. This implies that El Nino is likely to be strengthening through the monsoon period, again not a good sign for this year’s rainy season.
In its first forecast issued in mid-April, the India Meteorological Department predicted a normal monsoon in the country with rainfall pegged at 96% of the long period average. Among other factors, the forecast was based on conditions in the Pacific in February-March, when the chances of El Nino were lower and the event was predicted to develop only by July-August. IMD will update its monsoon forecast in late May or early June.
“El Nino is likely to form earlier than what the previous forecasts had indicated. However, the warming in the ocean takes some time to be transferred to the atmosphere, which is when its effects begin to be felt in other regions”, said Mrutyunjay Mohapatra, IMD chief.
“In recent years, we have seen El Nino mainly impacting the second half of the monsoon (August-September). The picture will be clearer by the end of this month,” he added.
The NOAA update shows currently temperatures in the central Pacific region called Nino 3.4, used for El Nino-La Nina forecasts, are close to the El Nino threshold. The latest weekly Nino 3.4 index value was +0.4oC, while El Nino conditions are said to begin when the index crosses 0.5o C.
Watch Parts of Delhi-NCR witness rains in early morning