Monsoon onset in city to be delayed beyond June 11: IMD

The onset of the southwest monsoon over the city is likely to be delayed beyond June 11, the weather bureau said on Friday. Independent meteorologists said that

The onset of the southwest monsoon over the city is likely to be delayed beyond June 11, the weather bureau said on Friday. Independent meteorologists said that the monsoon’s arrival over Mumbai was unlikely before June 15.

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The India Meteorological Department (IMD) on Friday issued its forecast for the onset of the southwest monsoon over Kerala on June 5 with a model error of ± 4 days while the advancement over the Andaman Sea, Andaman and Nicobar Islands, and some parts of southeast Bay of Bengal is expected over the next 48 hours.

“Since there is a delay over Kerala, we can infer that there will be delay over nearby areas extending up to Maharashtra. We can further infer that it will be slightly delayed for Mumbai from its new onset date of June 11,” said Mrutyunjay Mohapatra, director-general, IMD.

Many factors were considered to determine the date of onset for Kerala, said Mohapatra, including a low pressure weather system that is likely to intensify into cyclone Amphan over southeast Bay of Bengal. “Once it becomes a severe cyclonic storm moving north-northeast, it will influence the surrounding environment by pulling moisture, affecting the progression of the southwest monsoon. As the cyclonic system dies down, further monsoon progression is expected,” he said.

HT had reported on April 16 that the duration of the southwest monsoon over Mumbai has been extended by eight days after the weather bureau announced revised monsoon onset and withdrawal dates. The new onset date for Mumbai is June 11 (against June 10 originally) and the new withdrawal date has been declared as October 8 against the existing September 29.

Akshay Deoaras, independent meteorologist and Ph.D. researcher at the University of Reading said the coming cyclone was not the only reason for the delay. “Another important reason for the delay was the lack of support of phenomena such as the Madden-Julian Oscillation [a rain-bearing weather system]. “The presence of such factors can speed up the monsoon’s progression along the west coast,” said Deoras. “Current forecasts don’t indicate a robust progression of the monsoon towards Maharashtra after its onset over Kerala. We can anticipate its arrival in Maharashtra in the third week of June, resulting in a delay of a week in southern parts of Konkan while arrival in Mumbai, most of Vidarbha, Marathwada and central Maharashtra is unlikely before June 15.”