Cold air weakens Typhoon Koinu

The storm was located above the sea in the south of China's Guangdong Province at 10 a.m. Monday, with a wind speed of 88 kph, according to the National Center for Hydro-Meteorological Forecasting.

It is expected to move west at 5 kph, before devolving into a tropical depression at 7 a.m. Tuesday in the northeast of Hainan Island, the center added.

The drastic weakening of the typhoon can be attributed to its interaction with a mass of cold air coming down from the north.

The cold air is expected to reach the eastern parts of northern Vietnam first, before coming for the northern parts of central Vietnam and certain areas in the west of northern Vietnam.

The Japan Meteorological Agency said the storm's wind speed was higher than 80 kph, and would devolve into a tropical depression on Monday, even before it reaches Hainan Island.

The Hong Kong Observatory meanwhile said the storm would retain its strength as it reached Hainan Island, only devolving once it reaches the Gulf of Tonkin.

Rough seas are expected within the next 24 hours due to the impact of the storm.

The National Steering Committee for Natural Disaster Prevention has requested coastal localities from Quang Ninh to Khanh Hoa to monitor the storm's situation.

Koinu is the fourth storm to make an appearance on the East Sea this year. Meteorological agencies said there would be one to two storms and tropical depressions affecting Vietnam’s mainland this month.