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The onset of the southwest monsoon is being keenly watched this year as it may provide an early sign regarding its progress over the Indian subcontinent, particularly when El Niño is expected to rear its head during the latter half of the season.
Will the southwest monsoon miss its June 1 date with Kerala and will it be weak?
The India Meteorological Department and private weather forecaster Skymet suggests it might be delayed and weak, and needs to be watched closely.
The southwest monsoon normally sets in over Kerala on June 1, with a standard deviation of about 7 days.
"This year, the southwest monsoon onset over Kerala is likely to be slightly delayed. The monsoon onset over Kerala is likely to be on June 4 with a model error of 4 days," the Met office said in a statement.
The monsoon arrived in the southern state on May 29 last year, June 3 in 2021 and June 1 in 2020.
“Thunderstorms in North India on May 18 and quite strong in the last week of May. As of now, monsoon onset looks weak and delayed... will track this on a daily basis," tweeted Jatin Singh, founder-director of Skymet.
He also said sowing might get delayed in a subsequent tweet.
Explaining the reasons for the likely delay, Mahesh Palawat, vice-president, meteorology and climate change at Skymet, told Business Standard: “First is the anticyclone persisting over the Arabian Sea; it won't allow monsoon winds to reach Kerala coast on time. Second, is the cyclone over the Arabian Sea, 'Fabian,' which will disturb monsoon currents.”
The onset of the southwest monsoon is being keenly watched this year as it may provide an early sign regarding its progress over the Indian subcontinent, particularly when El Niño is expected to rear its head during the latter half of the season.
There is no direct correlation between the onset of monsoon and its pace of progress and a poor start to the southwest monsoon does not necessarily mean that rains will be deficient or patchy.
Timely and well-distributed rainfall is key to good agriculture production, more so when some forecasters are predicting a below-normal monsoon in 2024.
The IMD, in its first monsoon forecast for 2023 released in April, said that the June-September monsoon season is expected to be “normal” this year at 96 per cent of the long period average (LPA).
The forecast is with a model error of +/- 5 per cent and the LPA for 1971-2020 is 87 cm. This means, according to the IMD, total rainfall in India in the June-September period will be around 83.5 cm.
The met department based its observations on the two positive weather patterns expected to develop during the monsoon months.
First, it said that the Indian Ocean Dipole (IOD), which is at present in the neutral state, is expected to get positive during the southwest monsoon season.
That apart, below-normal snow covers over the Northern Hemisphere and Eurasia in February and March 2023 that tends to have adverse relations with the Indian monsoon will contribute in making the monsoon normal, the IMD said.
The data showed that there is a 35 per cent probability of monsoon being normal, 29 per cent chance of it being below normal, 22 per cent chance of it being deficient, 11 per cent chance of it being above normal, and just 3 per cent chance of it being excess.
In contrast, Skymet said that the southwest monsoon in 2023 is expected to be “below normal” at 94 per cent of the LPA due to the impact of El Niño, which has reared its head after four consecutive years of normal to above-normal rains.
In terms of quantum, the private weather forecasting agency said that rainfall in the June-September period that provides more than 70 per cent of the country’s annual precipitation is expected to be at 816.5 mm, as against the normal of 868.8 mm.
The forecast is with an error margin of +/- 5 per cent.
With inputs from PTI
