Siliguri, May 26: Cyclone Aila that had developed over the Bay of Bengal moved northward last night and weakened after causing storm and rainfall in the state’s northern districts.

Officials at the Indian Meteorological Department and the Hong Kong-based World Meteorological Organisation issued alerts today, forecasting that the depression would hit sub-Himalayan Bengal, Sikkim, parts of Bihar and Jharkhand and the northeastern states.

In a release issued by the IMD at 11.30am today, the experts said the depression was centred in the sub-Himalayan Bengal at 8.3am today, hovering around 50km north of Malda.

“The system is likely to move in a near northerly direction and weaken into a depression during the next six hours,” the release said.

Under its influence, the weather experts said there would be heavy to very heavy rainfall at a few places and isolated extremely heavy rainfall in sub-Himalayan Bengal, Sikkim, Assam, Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura and Meghalaya in next 24 hours. They had also forecast storm at 50-60kmph, leading to uprooting of trees and destruction of huts in rural areas.

Officials at the Regional Meteorological Office in Jalpaiguri said it had rained heavily in the hills and in the catchment areas of the Teesta.

Heavy rains in the hills swelled rivers like Balason and Mahananda, flowing in and around Siliguri. Water level in other rivers also increased. Officers at the North Bengal Flood Control Commission, however, said no alert had been issued.

“There were some minor breaches on embankments and we apprehend that situation might worsen if it rains more in the hills,” said Asok Bhattacharya, the Bengal minister for urban development, here today.

“Officials have been asked to identify school buildings which can be used as flood shelters. The irrigation department has been instructed to keep sandbags ready,” he added.