The monsoon is likely to set in over Kerala with a “slight delay” on June 4, the India Meteorological Department (IMD) said on Tuesday. The usual onset date over Kerala is June 1, within a seven-day window.
The IMD in April forecast a “normal” monsoon during the June-September season, though at 96% of the Long Period Average (LPA), it is at the lowest end of what the agency categorises as “normal rainfall.”
The LPA represents the average monsoon rainfall over India of 89 cm. The major factor expected to cause diminished rains this year is the development of an El Nino, a cyclical phenomenon of warming in the Central Pacific that six in 10 years is linked to diminished rainfall in west, northwest and western parts of Central India. Since 2019, India has been under the influence of the converse ‘La Nina’ or a cooling in those regions, and therefore substantial monsoon rains.
Also read: As Cyclone Mocha makes landfall, countdown for southwest monsoon begins
The arrival of the monsoon over Kerala does not have a bearing on the quantity of monsoon rain, though a timely arrival helps farmers prepare for kharif sowing. The IMD uses a dedicated weather model for forecasting the Kerala-onset and accounts for factors such as the minimum temperatures over northwest India, peak pre-monsoon (March-May) rainfall and winds in the upper reaches of the northeast Indian Ocean.
The monsoon’s arrival over Kerala is preceded by specific weather-heavy rains and clouding – over the Andaman and Nicobar (A&N) Islands by May 20. However the cyclone Mocha, that formed in the Bay of Bengal and landed in Myanmar, affected the progress of the monsoon system in the A&N islands and is partly responsible for the expected delayed arrival over Kerala, an IMD spokesperson told The Hindu. Cyclones tend to suck out moisture and impede rain-bearing systems. The Southwest monsoon was very likely to advance into the south Bay of Bengal, South Andaman Sea and Nicobar Islands within the next three days, officials confirmed.
