Sucharit Koontanakulvong, an expert from the department of water resources engineering at Chulalongkorn University, said the approximate flood level would be 20cm.
At least 11 areas around Bangkok are at risk. The areas are Lat Phrao, Min Buri, Phra Khanong, Bang Kae, along Khlong Prawet, Khlong Sam Wa, Khlong Song Wa, Khlong Phraya Ratchamontri, Khlong Phittayalongkorn, Khlong Thawi Wattana, and the area to the east of Suvarnabhumi airport.
The storm would bring with it heavy rainfall, Dr Sucharit said.
He said the water level in two major dams in the North _ Bhumibol and Sirikit _ would be kept at 60% of total capacity, which means the dams still have space to store water.
The Meteorology Department said the level of rainfall in the lower Chao Phraya River basin last month was equivalent to one-third of the rainfall in the area over the whole year average of the past two years.
Climate change, canal encroachment and urban expansion could be also blamed for the flooding in Bangkok this year, Dr Sucharit said.
The government has set aside 20 billion baht to improve the drainage system and create water retention areas in Bangkok. However, Dr Sucharit said only 50% of the work has been done.
Kangwan Deesuwan, the director of the main drainage system development division of the Bangkok Metropolitan Administration, said the BMA had cleared more than 1,600 waterways and canals and 6,400km of underground drainage pipes around Bangkok to handle possible floods in the capital this weekend.
Several canals would channel water out of central Bangkok, while the BMA has installed water pumps in many areas, Mr Kangwan said.