Cyclonic storm 'Roanu', formed over the Bay of Bengal, is set to intensify and bring heavy to very heavy rains in West Bengal from Friday night, the Regional Meteorological Centre said.

Earlier, the India Meteorological Department had predicted that 'Roanu' was likely to intensify into a severe cyclonic storm and hit Andhra coast.

"Thundershowers due to Roanu will lash Bengal districts and Kolkata starting late evening today (Friday). Roanu is likely to cross coastal Bangladesh on May 21 night or early morning on May 22. On the way, the cyclone will hit Bengal," said an RMC official in Kolkata.

Fishermen have been advised not to venture into the sea.

Officials said heavy to very heavy rainfall is likely in most places over coastal Gangetic West Bengal during the next 48 hours.

Sea waves are very likely to be high to very high along and off Bengal coast during next 48 hours, the IMD said.