Monsoon rains to be 'slightly delayed', hit Kerala on June 4: IMD

June 4 or 7? IMD, Skymet differ on monsoon onset

The southwest monsoon in all probability will arrive late over Kerala coast this year, with the state-run India Meteorological Department (IMD) predicting the onset date to be June 4, even as private weather forecasting agency Skymet said it would arrive no later than June 7.

IMD’s forecast is with a model error of plus/minus four days; Skymet’s with a model error of plus/minus three days.

The normal onset date for the southwest monsoon over Kerala coast is June 1 every year.

The Met department said the onset was expected to be ‘slightly delayed’ in 2023.

“The southwest monsoon is very likely to advance into some parts of the South Bay of Bengal, South Andaman Sea, and Nicobar Islands in the next two to three days,” the Met department said in a late-night update.

IMD gives out its monsoon onset forecast based on an indigenously developed statistical model that uses six parameters, said an official statement.

The Met said that in 18 years (starting 2005), its operational forecast has been correct, except in 2015.

The onset of the southwest monsoon is being keenly watched this year. It could provide an early sign of its progress over the Indian subcontinent, particularly when the emergence of the El Niño weather pattern has raised concerns about rainfall in 2023.

A poor start to the southwest monsoon does not mean rainfall will be deficient or patchy. Timely and well-distributed rainfall is key to getting good agriculture production in any given year, more so when some weathermen are predicting a below-normal monsoon in 2024. 

Meanwhile, Skymet, in its onset forecast, also warned that hot weather conditions would continue deep into June this year over central and northern parts of the country.

“This may not augur well for kharif sowing,” it said in a statement.

Explaining the reasons behind the delayed onset of monsoon, Skymet said a powerful Cyclone Fabien was moving over the South Indian Ocean in the equatorial latitudes, abeam Southern Peninsula.

“The hurricane-strength weather system will take nearly one week to clear the area. This monster storm is restricting the cross-equatorial flow and build-up of the monsoon stream,” said Skymet.

There is an anticyclone developing over the Arabian Sea that will also act as a deterrent to the smooth streaming of monsoon flow from the Arabian Sea to the West Coast.

Both IMD and Skymet also differed in their monsoon forecast for 2023 earlier made in April.

While IMD said monsoon this year would be ‘normal’ at 96 per cent of the long period average (LPA), Skymet said it would be ‘below normal’ at 94 per cent of LPA due to the emergence of El Niño.

The LPA of June-September rainfall for the period between 1971 and 2020 is 87 centimetres. Both forecasts are with a model error of plus/minus 5 per cent.

IMD will come out with its region-wise forecast for June-September rainfall later in the month.