New Delhi, May 20 (IANS): The "extremely severe" cyclonic storm Amphan is only 100 km from Digha in West Bengal, where it is slated to make a landfall in a few hours, and is whirling at a speed of at least 160 km per hour gusting to 180 kmph.

Lakhs of people in West Bengal and Odisha have been evacuated from vulnerable areas.

According to an update of the India Meteorological Department, the cyclone lay currently centred about 170 km east-northeast of Odisha's Paradip, 105 km south-southeast of West Bengal's Digha and 90 km from Sagar Island and 240 km southwest of Bangladesh's Khepupara.

Amphan will move north-northeast and cross West Bengal-Bangladesh coast between Digha and Hatiya Islands close to Sundarbans around Sagar Island in afternoon with a wind speed of 165 kmph, topping to 185kmph.

Landfall process will commence after 4 p.m. today. After the landfall, the system is likely to move close to Kolkata.

The storm surge during the landfall in West Bengal is expected to be four to six meters above astronomical tide. The surge is expected to inundate low- lying areas of South and North 24 Parganas and parts of East Medinipur district.

Wind speed in Kolkata, Hooghly and Howrah is likely to range between 110 kmph to 120 kmph gusting to 130 kmph which may cause extensive damage in urban areas also.

In coastal Odisha, wind speed will be 100 kmph to 110 kmph gusting to 125 kmph along and off Jagatsinghpur, Kendrapara and Bhadrak till afternoon on Wednesday and over Balasore till evening.

After the landfall, the system is very likely to continue to move north-northeastwards, across Gangetic West Bengal and Bangladesh and weaken gradually.

It is likely to maintain the intensity of Cyclonic Storm till the morning of May 21 and thereafter it will weaken into a deep depression over Bangladesh.

The system is being continuously tracked by the Doppler Weather Radar (DWR) at Odisha's Paradip and Gopalpur and Kolkata.