The meteorological department on Friday warned of heavy to very heavy rainfall in the Gangetic West Bengal till Saturday as the cyclonic storm 'Titli', which has weakened into a deep depression, moved towards northeast. The storm system is very likely to further lose steam and turn into a depression as it moves through Odisha and enter the Gangetic West Bengal after recurving northeastwards following landfall at Gopalpur in Ganjam district of Odisha, the weatherman said. It is, however, likely to cause heavy to very heavy rain in the Gangetic West Bengal, with North and South 24 Parganas, East and West Midnapore, Jhargram, East Burdwan, Howrah and Hooghly districts to be affected the most. Heavy rain is likely in Kolkata, Bankura, Purulia, Birbhum, Murshidabad, Malda, North and South Dinajpur districts till Saturday. Fishermen have been advised not to venture into the sea along and off the coasts West Bengal and Odisha, deep sea areas of North and Central Bay of Bengal till Saturday owing to rough to very rough sea condition. Squall with speed of 45 to 55 kmph, gusting to 65 kmph will prevail along and off the coasts of West Bengal and Odisha, the MeT department said. Tourists at Digha and adjacent sea-side resorts have been advised not to get into any sea-bound activities till Saturday.