El Niño Strengthens, More Likely to Continue During Monsoon Months
As the monsoon approaches, a comeback by El Niño might upset expectations of normal rainfall in India. Beating predictions that it may fade away quickly, El Niño, the ‘bad boy’ of global weather, has continued to strengthen over the past month. American scientific agency, National Oceanic and Atmospheric Administration (NOAA), reported on Thursday that the sea surface and atmospheric conditions that mark the formation of El Niño became increasingly well-defined during this period.
Significantly for India, NOAA forecasters have said that there is a 60% chance of El Niño conditions continuing through June to August. Previously, experts believed that the possibility of El Niño continuation beyond May was less than 50%. The initial confirmation of the El Niño formation came in mid-February.
Although El Niño did strengthen in February, its overall strength is expected to remain weak, meaning El Niño may not dominate global weather patterns. Therefore, the impacts may not be widespread. However, experts suggest caution, as the increased probability of El Niño continuation during monsoon months is always a threat to the amount of rainfall. An El Niño of any strength can reduce the amount of monsoon rainfall and thus have significant local impacts.
So why does El Niño matter to India?
Monsoon winds are primarily drawn towards Indian landmass due to the difference in temperature between ocean and land temperatures. Moisture-bearing winds flow from the cooler waters off Africa towards India, drawn by India’s summertime heat. But El Niño dampens the conditions needed for attracting these winds towards India. Therefore, El Niño is often associated with lower-than-normal rainfall in India.
Interestingly, the India Meteorological Department (IMD) still maintains that neutral El Niño–Southern Oscillation (ENSO) conditions are prevailing at present, indicating no El Niño formation.
How scientists identify formation of El Niño
El Niño is a warming phase of ENSO wherein the trade winds weaken or reverse and the area of warmer water spreads in the central and eastern Pacific. The formation is confirmed when sea-surface temperatures in central and eastern equatorial Pacific are at least 0.5°C warmer than average for two consecutive months or are expected to last for three consecutive months.
In addition, the atmosphere also needs to exhibit certain characteristics such as increased rain in the central Pacific and reduced rain over Indonesia. While above-average sea-surface temperatures have generally been in place since last September, the atmosphere did not reflect El Niño conditions until January. It was only by late January that meteorologists finally had enough evidence that the atmosphere was responding to the warmer ocean, confirming the formation of El Niño.