New Delhi, May 24 : A yellow alert has been declared both in Odisha and West Bengal after cyclonic storm 'Yaas' moved slowly north-northwestwards and was very likely to intensify further into a severe cyclonic storm during the next 12 hours, the IMD said. It is expected to intensify into a very severe cyclonic storm during the subsequent 24 hours, said the India Meteorological Department's National Weather Forecasting Centre. As of 8.30 a.m. on Monday, Yaas laid centered over east central Bay of Bengal at latitude 16.4 degree north and longitude 89.6 degree east, about 620 km north-northwest of Port Blair (Andaman Islands), 530 km south-southeast of Paradip (Odisha), 630 km south-southeast of Balasore (Odisha) and 620 km south-southeast of Digha (West Bengal). It would continue to move north-northwestwards, intensify further and reach northwest Bay of Bengal near north Odisha and West Bengal coasts by May 26 early morning. "It is very likely to cross north Odisha-West Bengal coasts between Paradip and Sagar islands around noon of May 26 as a very severe cyclonic storm." Light to moderate rainfall at many places with heavy falls at isolated places is expected in north coastal Andhra Pradesh on Monday and heavy to very heavy falls at isolated places in the region on Tuesday. In Odisha, light to moderate rainfall at many places with heavy falls at isolated places over coastal region of the state on Monday has been predicted by the IMD with heavy to very heavy rainfall in Puri, Jagatsinghpur, Khurda, Cuttack, Kendrapara, Jajpur, Bhadrak, and Balasore districts and heavy over Ganjam, Dhenkanal, Mayurbhanj districts later in the day. Heavy to very heavy rains at a few places with extremely heavy falls at isolated places in Jagatsinghpur, Cuttack, Kendrapara, Jajpur, Bhadrak, Balasore, Mayurbhanj, Dhenkanal, Keonjhargarh and heavy falls at isolated places in Puri, Khurda, Angul, Deogarh, and Sundergarh is expected on May 26. Heavy rainfall at isolated places in north interior Odisha may take place on May 27. In West Bengal and Sikkim, the IMD forecasts light to moderate rainfall at most places with heavy to very heavy rainfall over Medinipur, South 24 Parganas and heavy rainfall at isolated places in Howrah, Hooghly, and North 24 Parganas districts on Tuesday. Extremely heavy rainfall is expected at isolated places over Jhargram, Medinipur, South 24 Parganas and heavy to very heavy rainfall at a few places in Purulia, Bankura, Bardhaman, Howrah, Hooghly, Kolkata, North 24 Parganas, Birbhum and heavy falls at isolated places over Nadia, Murshidabad, and Darjeeling districts on May 26. The IMD said there is possibility of heavy to very heavy rain at isolated places in Malda and Darjeeling, Dinajpur, Kalimpong, Jalpaiguri, Sikkim and heavy rain at a few places over Bankura, Purulia, Bardhaman, Bhirbhum and Murshidabad on May 27. Light to moderate rainfall at most places with heavy to very heavy rainfall and extremely heavy falls at isolated places is expected in Jharkhand on May 26 and 27 and isolated heavy falls on May 28. The IMD has predicted light to moderate rainfall at most places in Bihar with heavy to very heavy rainfall and extremely heavy falls at isolated places on May 27 and isolated heavy to very heavy falls on May 28. Light to moderate rainfall at most places with heavy to very heavy rainfall at isolated places on May 26 and 27 is expected in Assam and Meghalaya. Gale winds, at speeds reaching 65-75 kmph and gusting to 85 kmph, are prevailing over west central Bay of Bengal. These are very likely to increase further becoming gale winds of speed, reaching 90-100 kmph and gusting to 110 kmph, over major parts of central Bay of Bengal by Monday evening and would decrease gradually from Tuesday afternoon. /IANS