The onset of the monsoon over Kerala is expected to be a bit delayed this year, with the Indian Meteorological Department (IMD) forecasting that it should arrive by June 5, instead of June 1. There is a model error of four days in the forecasting, the IMD adds.
However, over the next 48 hours, the southwest monsoon should advance into the Andaman Sea, Andaman and Nicobar Islands and some parts of southeast Bay of Bengal. As per past data, meteorologists say there is no association of the date of monsoon advance over the Andaman Sea with either the date of monsoon onset over Kerala or with the seasonal monsoon rainfall over the country.
In April, the IMD had said that the chances for a normal monsoon are high (41 per cent) and chances for an above-normal monsoon are 21 per cent.
In the Indian monsoon season, initial monsoon rains are experienced over south Andaman Sea and the monsoon winds then advance in a north-westward direction across the Bay of Bengal. This is earlier than the normal date for onset of southwest monsoon over the Andaman Sea that is around May 22, as per the new monsoon calendar, which was released by the IMD on April 15. At present, there is a well-marked low pressure area over southeast Bay of Bengal, which is very likely to concentrate into a depression over the next 12 hours, and further into a cyclonic storm by May 16.
“Associated with this event, conditions are likely to become favourable for advance of the southwest monsoon into Andaman Sea, Andaman and Nicobar Islands and some parts of southeast Bay of Bengal during the next 48 hours,'' the IMD stated.
Last year, too, the monsoon hit the Kerala coast late, on June 8, a delay of seven days. The progress into the south peninsula and central India too remained sluggish, mainly due to the formation of a very-severe cyclonic storm over the Arabian Sea from June 10 to 17, which sucked out a lot of the moisture.
In fact, the entire country was covered by the monsoon rains only on July 19, a delay of four days. This resulted in a 33 per cent monsoon deficit in June. However, the monsoon progressed rather furiously in the latter part of the season, with several record-breaking instances of extreme rainfall and resultant floods over vast swathes from July to September. In fact, the rains withdrew over northwest India on October 9 as against the normal date of September 1. In fact, there was hardly any gap between the final withdrawal of the monsoon over the country (October 16) and the onset of the northeast monsoon: The two events happened simultaneously.
The IMD, this year, released a new monsoon schedule. However, even under the new calendar, the scheduled onset over Kerala remains the same, around June 1. As per the new normals, the coverage over the entire country is one week before the existing normal. However, monsoon withdrawal from northwest India is delayed by more than two weeks compared with the existing normal date of September 1. Monsoon retreats from most parts of the country, except south peninsula and some parts of neighbouring central India by October 15, coinciding with the existing normal, and subsequently northeast monsoon gets established over the south Peninsula.
