A storm with wind speeds touching 160km an hour is barrelling towards Bengal from the Bay.

Winds clocking 100kmph are likely to blow across Calcutta, accompanied by heavy rain, when Amphan hits south Bengal as an “extremely severe cyclonic storm” between Wednesday afternoon and evening, the Met office at Alipore said on Monday.

Named by Thailand, Amphan (pronounced Um-Pun) is likely to make landfall between Digha in Bengal and Hatiya island in Bangladesh, near the Sunderbans.

What is the new worry?

The storm is approaching in the middle of the Covid crisis that has made social distancing indispensable. It will be a challenge to maintain social distancing in storm shelters.

Officials said the focus was on increasing the number of shelters to factor in the social-distancing norms. East Midnapore’s seven blocks have 43 cyclone shelters where 50,000 people can be accommodated. However, social-distancing norms have forced the administration to requisition nearly 600 schools in the coastal zone to ensure people are accommodated maintaining Covid-19 protocol.

If needed, the officials are keeping open the possibility of making use of around 1,000 hotels in Digha that are vacant because of the lockdown.

Where is the storm?

On Monday evening, the storm was a “super cyclone” over the Bay of Bengal. It was 890km from Digha and 730km from Paradip (Odisha). The system was generating wind speeds of over 200kmph and travelling at less than 10kmph. Barging towards land, the storm is likely to lose some steam and make landfall as an “extremely severe cyclonic storm”.

When is it likely to reach Bengal?

The exact time of the landfall will be clear as the storm comes near land, said a Met official. As of Monday evening, it was expected to hit land between Wednesday afternoon and evening. North and South 24-Parganas, especially the Sunderbans and East Midnapore, will bear the brunt of the storm, said G.K. Das, director, India Meteorological Centre in Alipore. At the time of landfall, the storm is expected to generate wind speeds of 160kmph and above, with gusts clocking 195kmph, a Met bulletin said.

What will be the effect on Calcutta?

Calcutta, Howrah and Hooghly are also likely to see widespread rain and winds from Tuesday evening. The intensity of both should go up from Wednesday. From Wednesday afternoon, Calcutta is tipped to see winds blowing at 70kmph and above, with gusts clocking 100kmph, said Das. Moderate rain is expected in the city on Tuesday and “heavy to very heavy rain (60 to 199mm over 24 hours)” from Wednesday.

Will Amphan pass directly over Calcutta?

No. The eye of the storm is likely to pass through the east of the city.

What after landfall?

The storm is likely to degenerate into a deep depression after hitting Bangladesh.

How is Amphan likely to be different from Aila, Fani and Bulbul?

Aila (2009) had struck the Sunderbans at 110kmph and its maximum speed was 103kmph when it was blowing through the city. Aila had made landfall in Bengal and tall waves had wreaked havoc along the coast. Das, the director of IMD Calcutta, said that as of Monday, Amphan was a stronger system than Aila. “But Aila made landfall closer to Calcutta than Amphan is expected to,” he said.

In May 2019, Fani had made landfall near Puri. Under its impact, the maximum wind speed in Calcutta was to be 100kmph. But it fizzled out when it passed over the city.

Bulbul made landfall on November 10 last year between Sagar islands in the Sunderbans delta of Bengal and Khepupara in Bangladesh as a severe cyclonic storm. But it caused little rain in Calcutta.