The cyclone is expected to make landfall between Digah in Bengal and Hatiya Islands in Bangladesh on Wednesday.
A high-level meeting is also scheduled today.
Wind speed could reach 170-180 kmph by today
The cyclone is expected to touch a wind speed of 170-180 kmph by Monday.
"The very severe cyclonic storm 'AMPHAN' (pronounced as UM-PUN) over central parts of South Bay of Bengal moved north-northeastwards with a speed of 13 kmph during the past six hours, intensified into an Extremely Severe Cyclonic Storm," a statement by India Meteorological Department, IMD, read this morning.
The storm will intensify in the next few hours: IMD
About the path ahead, IMD said in the next six hours or so, the storm will further intensify. The storm will quickly move towards north-northeastwards across the northwest Bay of Bengal and cross West Bengal, the IMD said.
It will make landfall by Wednesday afternoon or evening.
This cyclone will be the strongest one to hit Odisha-Bengal coast since Phailin in 2013.
Rains will lash parts of Bengal on Wednesday
The cyclone could lose intensity just before landfall, but the impact could be severe, nevertheless.
Weather officials believe East Midnapore, North and South 24 Parganas will receive heavy rainfall.
Heavy showers will also be witnessed in Howrah, Hoogly, and West Midnapore. In Kolkata, the wind speed could touch 70-80 kmph with heavy rainfall on Wednesday, said Regional Meteorological Centre (RMC) director GK Das.
Odisha will deal with maximum impact: IMD scientist
A scientist with IMD Bhubaneswar said Odisha will face the maximum impact of the cyclone. "Wind speed expected to be 110-120 kmph, gusting up to 130 kmph. Balasore, Bhadrak, Jajpur, Mayurbhanj districts can be affected on 20 May," said Umashankar Das.
NDRF sent seven teams to Bengal, 10 to Odisha
The National Disaster Response Force is closely monitoring the developments and has sent teams as well, NDRF Director-General SN Pradhan said earlier.
Seven teams were sent to Bengal's South 24 Parganas, North 24 Parganas, East Midnapore, West Midnapore, Howrah, and Hooghly.
Similarly, 10 teams were deployed in Odisha, specifically at Puri, Jagatsinghpur, Kendrapara, Jajpur, Bhadrak, Balasore and Mayurbhanj. One team has nearly 45 personnel.
PM Modi will chair meeting at 4 pm
Meanwhile, fishermen were advised against venturing into the sea till May 21 and those who are already out were asked to return.
Reportedly, Prime Minister Narendra Modi will chair a high-level meeting with the Ministry of Home Affairs (MHA) and the National Disaster Management Authority (NDMA) at 4 pm today to "review the arising cyclone situation in parts of the country".