The southwest monsoon is likely to arrive over Kerala on May 26, nearly six days ahead of the normal onset date of June 1, according to the India Meteorological Department (IMD). However, weather experts have cautioned that an early arrival does not necessarily guarantee a strong monsoon season, especially with El Niño conditions expected to emerge later this year.
The IMD said conditions are favourable for the monsoon to advance over parts of the south Bay of Bengal, the Andaman Sea and the Andaman and Nicobar Islands within the next 24 hours. Widespread rainfall activity is also expected along the southern west coast till May 28.
Last year, the monsoon had reached Kerala on May 24. The IMD noted that this year’s forecast carries an error margin of four days, while the normal onset date itself has a standard deviation of around seven days.
Early Monsoon Does Not Guarantee Strong Rainfall
Weather experts stated that there is no direct link between early monsoon onset and overall seasonal rainfall performance.
Mahesh Palawat, Vice President of Climate and Meteorology at Skymet Weather, said monsoon behaviour depends largely on the formation of low-pressure systems and the development of monsoon surges.
“There have been years when monsoon arrived early but rainfall remained weak. Monsoon progresses in surges and depends on atmospheric systems developing over time,” he said.
El Niño Signals Raise Concern
At the same time, global climate agencies have warned that atmospheric conditions in the Pacific Ocean are moving towards the development of El Niño, a weather phenomenon generally associated with weaker monsoon rainfall and higher temperatures in India.
The National Oceanic and Atmospheric Administration (NOAA) stated that there is an 82 per cent probability of El Niño developing between May and July and persisting into next year. The agency also indicated a more than 50 per cent chance of the event becoming strong or very strong between September and November.
Similarly, the US Climate Prediction Center said El Niño is likely to emerge soon and could intensify later this year.
IMD Predicts Below-Normal Rainfall
The IMD’s first-stage long-range forecast has already projected below-normal rainfall for the June-September southwest monsoon season.
According to the forecast, India is expected to receive rainfall at 92 per cent of the Long Period Average (LPA), with a margin of error of plus or minus five per cent.
The LPA for the country, calculated over the 1971-2020 period, stands at 87 cm.
The weather department stated that below-normal rainfall is likely across large parts of the country, while only some areas in northeast India, northwest India and south peninsular India may receive normal to above-normal rainfall.
The IMD is expected to release its second-stage monsoon forecast later this month.
How IMD Predicts Kerala Monsoon Onset
The IMD said the Kerala onset date is forecast using an indigenously developed statistical model operational since 2005.
The model uses six atmospheric and oceanic indicators, including minimum temperatures over northwest India, pre-monsoon rainfall over south peninsular India, outgoing longwave radiation (OLR) over the South China Sea and southwest Pacific region, and lower tropospheric winds over the Indian Ocean.
OLR is considered an important measure of cloudiness and atmospheric convection.
Heatwave Conditions Continue Across North India
Meanwhile, the IMD stated that a well-marked low-pressure area persists over the southwest and adjoining west-central Bay of Bengal, accompanied by cyclonic circulation.
The agency warned that heatwave to severe heatwave conditions are likely to continue over northwest and central India over the coming days.
At the same time, heavy to very heavy rainfall is expected over northeast India and parts of Tamil Nadu, Karnataka, Kerala, Puducherry and Karaikal during the next three to four days.
