New Delhi, May 17 (IANS): The India Meteorological Department on Sunday said that Cyclonic Storm Amphan in Bay of Bengal has intensified into a Severe Cyclonic Storm and will cross West Bengal and Bangladesh's Sagar and Hatiya island on May 20.

"The cyclonic storm over Southeast Bay of Bengal moved slowly north-westwards with a speed of three kmph during past six hours [and] intensified into a severe cyclonic storm," said Sunitha Devi, IMDAscientist in-charge for cyclones.

The cyclone currently lies centred about 990 km south of Odisha's Paradip, 1,140 km south-southwest of West Bengal's Digha and 1,260 km south-southwest of Bangladesh's Khepupara. "It is likely to intensify further into a very severe cyclonic storm during the next 12 hours," she added.

It is also likely to move nearly northwards slowly during next 24 hours and then curve north-northeastwards and move fast across northwest Bay of Bengal and cross West Bengal-Bangladesh coast between Sagar Island and Hatiya Island during the afternoon or evening on May 20.

Heavy to extremely heavy rainfall, accompanied by high speed winds and tidal waves are expected in the region.

Fishermen are advised not to venture into the south Bay of Bengal for the next 24 hours. They are also advised not to venture off North Odisha, West Bengal and adjoining Bangladesh coast between May 18 and 20.

Squally wind speed reaching 45 to 55 kmph gusting to 65 kmph is likely to commence along and off south Odisha coast from May 18 evening, extend to along and off north Odisha coast from May 19 and along and off West Bengal coast the next afternoon.

"The wind speed will gradually increase, becoming gale wind speed reaching 75 to 85 kmph gusting to 95 kmph from 20 coming along and off north Odisha and West Bengal coasts. It will gradually increase thereafter along West Bengal coast," the weather department added.