In the evening of August 28, a tropical low pressure system strengthened into the fourth major storm called Lionrock, according to the National Hydro-Meteorological Forecasting Centre.
At 7am on August 29, the system was positioned at 19.7 degrees north latitude and 116.1 degrees east longitude, around 360km southeast of Hong Kong, China. It was traveling with winds gusting 62-74kph near its centre.
In the next 24 hours, the storm is expected to strengthen and move north at a speed of 10kph.
In the next 48-72 hours, the storm will travel between north-northeast at a speed of 5-10kmkph. It is estimated that at 7am on September 1, the centre of the system will be at 22.9 degrees north latitude and 117.6 degrees east longtitude, around 120km from Guangdong province, China.
The strongest wind gusts near the centre will be in the 9 or 10 storm category (75-102kph).
The northern East Sea will see strong winds and rough seas as a result of the storm.
The High Command of the Border Guard said on August 29 that they had informed 52,330 vessels with 237,486 fishermen on board about the storm.
The Central Steering Committee for Flood and Storm Prevention and Control has directed coastal provinces and cities to prepare for the storm and asked them to report on their flood prevention activities and the results of informing vessels at sea about the incoming storm.