The India Meteorological Department (IMD) on Wednesday revised its forecast and said Cyclone Nisarga is now likely to make landfall between 1pm and 4pm just south of Alibag, a resort town in Maharashtra’s Raigad district.

Cyclone Nisarga is now 130km south-southwest of Alibag, 175km south-southwest of Mumbai and 400km south-southwest of Surat, the weather bureau said.

It had said earlier that Cyclone Nisarha is expected to make landfall very close to Alibaug between 12pm and 3pm.

The severe cyclonic storm Nisarga has intensified with a wind speed of 100 to 110 kmph gusting to 120 kmph, officials added.

“It will make landfall as a severe cyclonic storm with a wind speed of about 110 kmph gusting to 120 kmph. Even though landfall site is south of Alibag, extensive damage can be expected in Raigad, Mumbai, Thane and neighbouring areas,” said Sunita Devi, head, national weather forecasting centre.

The diameter of the eye of the storm has decreased in the past hour and is about 65 km at present, indicating an intensification of the weather system. The wind speed too has increased from 85-95kmph to 90-100kmph (gusting to 110kmph).

The eye is the region of calm weather at the centre of tropical cyclones.

As conditions indicate further intensification, wind conditions will increase up to 100-110 gusting to 120 kmph. A higher sea surface temperature and low vertical wind shear favoured the intensification of severe cyclonic circulation, said IMD scientists earlier.

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.