Bangladesh’s flood forecasting agency warned on Wednesday that heavy to very heavy rainfall over the next 72 hours could push rivers above danger levels in four divisions, triggering flash floods, with conditions possibly improving from Saturday, the centre said.

The Flood Forecasting and Warning Centre said rapid rises in river levels were likely in the country’s northeast, east, southeast and north, potentially affecting parts of Sylhet, Sunamganj, Moulvibazar, Habiganj, Netrokona, Sherpur, Mymensingh, Chattogram, Feni, Cox’s Bazar, Khagrachhari, Bandarban, Nilphamari, Lalmonirhat and Kurigram districts.

Sarder Udoy Raihan, the centre’s executive engineer, said any flash flooding that develops could persist for three days, with conditions possibly improving from Saturday. All of the country’s main rivers are currently flowing below their danger marks.

A low-pressure system over the Bay of Bengal has brought rain to many parts of the country for about three days. In the 24 hours to Tuesday, Chattogram recorded 394 millimetres of rain and very heavy falls were also reported in Sylhet and Barisal divisions. Heavy rainfall was also recorded in upstream areas of India, including Meghalaya and Tripura.

The centre said the Teesta river could cross its danger threshold within 24 to 48 hours. Water levels in the Surma-Kushiyara, Gomti, Muhuri, Feni, Sangu, Matamuhuri, Dudhkumar and Dharla rivers are also expected to rise rapidly.

The meteorological office has forecast further heavy to very heavy rainfall across Chattogram, Sylhet, Mymensingh and Rangpur divisions and adjacent Indian areas over the next four days.