Cyclone Nisarga, the tropical storm expected to make landfall on Wednesday, is currently 165km south-southwest of Alibaug, 215km south-southwest of Mumbai and 440km south-southwest of Surat in Gujarat.
The Indian Meteorological Department (IMD) said in its 7am bulletin that it is expected to make landfall very close to Alibaug, a resort town in Maharashtra’s Raigad district, between 12pm and 3pm.
Nisarga has intensified into a severe cyclonic storm early on Wednesday morning and is currently recording a wind speed of 85 to 95kmph gusting to 105kmph. Typically, severe cyclonic storms make landfall with wind speeds of 100 to 110kmph gusting to 120kmph.
IMD scientists on Wednesday morning that diameter of Nisarga’s eye is about 65km as observed through the radar so it has decreased during past one hour indicating the intensification of the system.
The eye is the region of calm weather at the centre of tropical cyclones.
As a result, wind speed has increased from 85-95kmph to 90-100kmph gusting to 110kmph, the scientists said. Wind conditions will further increase up to 100-110kmph gusting to 120kmph as conditions are favourable for intensification.
The higher sea surface temperature and low vertical wind shear favoured the intensification of severe cyclonic circulation, they said.
IMD has issued a red alert for at least seven coastal districts of Maharashtra, while several districts along Gujarat’s coast are also expecting heavy rainfall.
Efforts to evacuate residents of these coastal districts were underway all of Tuesday even as the Prime Minister’s Office assured all help to state officials.
Mumbai, which is on the path of the cyclone, will likely receive very heavy rainfall upwards of 164mm. The city is already reeling under a high caseload of the coronavirus disease (Covid-19) cases, and the possibility of inundation of low-lying areas has raised concerns over the strain on healthcare infrastructure and municipal resources.
A predicted storm surge of about 1-2 metres height above astronomical tide is likely to inundate low lying areas of Mumbai, Thane and Raigad districts and 0.5-1 metre height above the astronomical tide is likely to inundate low lying areas of Ratnagiri district during the time of landfall.
A June 2 Indian National Centre for Ocean Information Services bulletin indicated a very rough sea along the Konkan coast: from 5.30pm on Tuesday to Wednesday evening, the wave height could be as high as 2.5 to 4 metres in Thane; 2.5 to 4.5 metres in Greater Mumbai; 3 to 6.5 metres in Ratnagiri; and 3 to 5.5 metres in Sindhudurg.
“The last severe cyclonic storm to hit close to Mumbai was in 1961. This storm is severe but with a wind speed of only 100 to 110kmph. Important thing is to take all precautions possible which state governments are trying. Inundation is possible so evacuation of vulnerable people is important,” M Mohapatra, IMD’s director general, said on Tuesday.
“It is not common for tropical cyclones to hit Maharashtra coast. Usually, during monsoon onset the cyclones that develop move towards Oman and Yemen coasts. The track of the cyclone is completely dependent on wind direction and pressure while warm ocean surface gives energy and intensity to the cyclone,” Sunita Devi, the head of the national weather forecasting centre, said.
The sea surface temperature in parts of the Arabian Sea is 31 to 32 degree Celsius compared to 28 degree Celsius expected during this season.
Nisarga is the 65th named cyclone in the north Indian Ocean and its name, proposed by Bangladesh, means ‘nature’ in Bengali.