The most important weather event of the country, the southwest monsoon, is making news of hope. Riding on a monsoon forecast released by Skymet Weather Services yesterday, a private weather forecaster, the media is awash with how this monsoon is going to be above normal.
The private forecaster has pegged the monsoon at 105 per cent, surpassing the normal of 889 mm by almost 5 per cent. Another private weather agency, Weather Risk Management Services had predicted 104 per cent monsoon rains earlier this month. The latter’s maiden optimistic monsoon forecast, levels with the collective view about monsoon 2016.
The government had also been bullish with statements by the agriculture secretary pointing to a good monsoon this year. To top it all, the India Meteorological Department, the government’s face on weather and climate, preponed their monsoon forecast, from a typical third/fourth week of April announcement, to today. To reveal the obvious without further delay probably incited such rescheduling.
The IMD's prediction is the most cheerful of them all. The government forecaster expects 106 per cent rains for the monsoon season this year. The monsoon is likely to be fairly well distributed with some hiccups in northeast and southeast India.
Answering to a question, Dr LS Rathore warned that some episodic heavy rainfall events may occur, causing floods in pockets. 'Such heavy rainfall events are common in years of above normal monsoon rainfall,' he added.
India receives nearly 80 per cent of its annual rainfall during the June-to-September southwest monsoon also known as JJAS (June, July August, September) in weather circles. The southwest monsoon is the primary source of irrigation in rain-fed areas that accounts for more than half the crop area during the Kharif growing season.
But what is driving such euphoria after two back to back deficit monsoons, something echoed by all published forecasts? The death of the much hyped Godzilla El Niño is an important stimulus. Moreover, a shift to La Niña is also stirring in the Pacific.
El Niño and La Niña are respective warming and cooling of sea surface temperatures over the tropical eastern Pacific, an irregular cyclical climate spectacle together known as the El Niño—Southern Oscillation (ENSO). An El Niño or a La Niña is termed strong if it is two degrees Celsius above or below normal respectively for a period of consecutive three months.
The current El Niño (2015-16) is only the third in the history of strong El Niño and the two preceding it occurred in 1982-83 and 1997-98. While the sting is out of the present El Niño, the La Niña is expected to come together only by autumn or winter this year.
Scientists at the International Research Institute for Climate and Society at the Columbia University, New York (IRI) are certain of a neutralizing ENSO (near normal sea surface temperatures) by summer. In addition, they are predicting a 50 per cent chance of an emerging La Niña by autumn and a little over 50 per cent chance by winter 2016.
Now that the El Niño phase is ending and its juxtaposing La Niña is emerging, the southwest monsoon is expected to receive a shot in the arm. The Indian southwest monsoon is typically drier than usual under an El Niño and wetter than average during a La Niña phase.
IMD also mentioned that the Indian Ocean Dipole (IOD), the other significant factor affecting the southwest monsoon, is positive right now. Though no direct correlations have been established between IOD and monsoon, a positive IOD typically contributes to above normal rainfall in central India.
IOD is a sporadic see saw of warmer and cooler sea surface temperatures between the eastern and western Indian Ocean. A cooler than average eastern Indian Ocean (with corresponding warmer than average western Indian Ocean) is known as positive IOD while the opposite phenomenon is known as a negative. The IOD is likely to turn neutral towards the second half of the monsoon.
A good monsoon is imperative this year for the survival of Indian agriculture as two deficit monsoon have stressed the sector hugely. While the monsoon was 12 per cent below normal in 2014, the shortfall intensified to 14 per cent below normal in 2015. The agriculture sector has witnessed a contraction of 0.2 in growth during 2014-15.
Columnist
Indranil is a weather industry expert with a decade long experience in the domain. He has been instrumental in setting up novel weather services across landscapes for both agriculture and industry, raising capital and crafting a growth story for weather forecasting in India. Currently he is Senior Vice President of Express Weather.
