Monsoon to be late by 4 days in Kerala
The onset over Kerala marks the beginning of the four-month monsoon season when India receives 70% of its annual rainfall.
The onset of south-west monsoon over Kerala is likely to be delayed by four days and is expected to arrive on June 5, the India Meteorological Department (IMD) said on Friday. The monsoon, however, is likely to arrive over the Andaman and Nicobar Islands four days in advance over the next 48 hours, it added.
The onset over Kerala marks the beginning of the four-month monsoon season when India receives 70% of its annual rainfall. IMD’s south-west monsoon forecasts provide critical information to at least 700 million people in India, who are directly or indirectly dependent on agriculture for livelihood. The delay could have implications for farmers impacted by economic slowdown associated with the Covid-19 pandemic and the lockdown imposed to check its spread. The lockdown has disrupted the traditional farm-to-fork supply chains.
The monsoon is crucial for the yield of rice, wheat, sugarcane, and oilseeds in a country where farming accounts for about 15% of the economy but employs over half of its people. The monsoon generally starts in June before it begins to retreat by Sept 1. In 2019, the monsoon started with the driest June in five years. Below-average precipitation followed in July before heavy rains caused flooding in August.
An abnormally higher number of western disturbances affecting the western Himalayan are among the reasons that can make monsoon advancement slightly sluggish and delay its onset over Kerala.
Western disturbances are low-pressure systems that generally originate over the Mediterranean region and are known to bring winter rain in India. Their intensity reduces in summer when they move to upper latitudes.
“We are seeing stronger mid-latitude westerly activity, which will delay the establishment of monsoon flow over the Southern Peninsula,” said DS Pai, a senior scientist and monsoon expert at IMD, Pune.
“At the same time, the development of cyclone near the Andaman and Nicobar Islands is pulling the monsoon winds to that region. So even if the monsoon is established, monsoon flow will get delayed; its progression will be impacted,” added Pai.
There is a well-marked low-pressure area over the south-east Bay of Bengal and its neighbourhood. It is likely to concentrate into a depression over the same region during the next 12 hours and further intensify into a 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 the advancement of Southwest monsoon into the Andaman Sea, Andaman and Nicobar Islands, and some parts of southeast Bay of Bengal, during next 48 hours, the IMD said in a statement.
Past data suggests that there is no association of the date of monsoon advance over the Andaman Sea either with the date of monsoon onset over Kerala or with the seasonal monsoon rainfall over the country, the statement added.
Union 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 will not be monsoon rains. For monsoon advancement, several parameters have to be met including temperature, wind speed, convection north of Australia, and many others.”
Rajeevan said the onset of the monsoon over Kerala is not a local phenomenon. “There are many large-scale changes. It has also been seen when there is cyclone development over the Bay of Bengal, the advancement of monsoon is slightly delayed as monsoon winds are pulled there.”
When asked if the unusually high westerly activity this year is a result of the climate crisis, Pai said it will be too early to say that. “The reasons have not 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 monsoon progresses after June 5 depending on other factors,” Pai added.
