Heavy rainfall is expected to pound Andhra Pradesh, Telangana and Odisha due to cyclonic storm 'Roanu', which will intensify into a "severe cyclonic storm" by tonight, the India Meteorological Department said.

Issuing alerts to the three states, the MeT said although the cyclone will make a landfall in Bangladesh on the intervening night of May 21 and 22 "heavy to very heavy rainfall" is expected in Andhra Pradesh, Telangana and Odisha.

"The system is likely to intensify into a severe cyclonic storm by tonight.

 Continuing moving northeastwards, the system is likely to cross south Bangladesh coast between Khepupara and Cox's Bazar on the night of May 21 and early morning of 22 and May as a cyclonic storm," Cyclone Warning Division of the IMD said.

"Rainfall at most places with heavy to very heavy falls at a few places and isolated extremely heavy falls very likely over coastal Andhra Pradesh during next 24 hours and heavy to very heavy at a few places during subsequent 24 hours.

"Rainfall at many places with heavy to very heavy falls at isolated places very likely over coastal Odisha during next 24 hours and heavy to very heavy falls at few places on May 20 and isolated heavy rainfall on May 21 at most places with isolated heavy falls very likely over Telangana and Rayalaseema during next 24 hours," the CWD added.

Sea condition is very likely to be rough to very rough along and off Andhra Pradesh and South Odisha coasts during next 48 hours and off North Tamil Nadu coast during next 24 hours.

Sea along coast off West Bengal is also likely to be rough to very rough on May 20 and 21.

"Storm surge of about 0.5 to 1.0 metre is likely along Andhra Pradesh coast during next 24 hours," the CWD added.