New Delhi: The onset of the southwest monsoon over Kerala is likely to be delayed by four days this year, and the expected date now is June 5 as against the normal date of June 1, according to the India Meteorological Department (IMD).
But the monsoon is likely to arrive over the Andaman and Nicobar Islands four days in advance, in the next 48 hours, IMD said in a statement on Friday.
The delayed monsoon onset over Kerala is being attributed to several factors that can make the advancement of rains slightly sluggish, including an abnormally high number of western disturbances affecting the western Himalayan region, scientists said.
“We are seeing stronger mid-latitude westerly activity, which will delay the establishment of monsoon flow over the southern peninsula,” said DS Pai, senior scientist and monsoon expert at IMD Pune.
“At the same time, the development of a cyclone near Andaman and Nicobar is pulling monsoon winds to that region. So, even if monsoon is established there, monsoon flow will get delayed, and its progression will be impacted,” he added.
A well-marked low-pressure area currently lies over southeast Bay of Bengal and its neighbourhood. It is likely to concentrate into a depression over the same region during next the 12 hours and further intensify into cyclonic storm Amphan over central parts of south Bay of Bengal by May 16.
Due to the development of the cyclone, conditions are likely to become favourable for advancement of southwest monsoon into the Andaman Sea, Andaman and Nicobar Islands and parts of southeast Bay of Bengal during the next 48 hours, IMD’s statement said.
Past data suggest there is no association between the date of the monsoon advancing over the Andaman Sea and the date of monsoon onset over Kerala or with seasonal monsoon rainfall across the country, the statement added.
Ministry of earth sciences secretary M Rajeevan said: “There will be some rains in Kerala associated with the development of the cyclonic storm over the Bay of Bengal but those are not monsoon rains. For monsoon advancement, several parameters have to be met, including temperature, wind speed, and convection north of Australia.
“Onset over Kerala is not a local phenomenon, there are many large-scale changes. It has also been seen that when there is cyclone development over Bay of Bengal, the advance of the monsoon is slightly delayed as monsoon winds are pulled there.”
Asked if the unusually high westerly activity this year is a result of climate change, Pai said, “It’s too early to say. The reasons haven’t been studied. It may be a result of natural variability but a high number of western disturbances can impact the flow of the monsoon. We have to see how the monsoon progresses after June 5, depending on other factors.”
IMD’s southwest monsoon forecasts provide critical information to at least 700 million people across India who depend, directly or indirectly, on agriculture for a livelihood. Delayed onset could have serious implications for farmers who are already impacted by the economic slowdown triggered by the Covid 19 pandemic.