Shortly after Tropical Storm Jebi made landfall over northern Vietnam, another area of low pressure was recognized northeast of Puerto Princesa, Palawan, the system is also favorable for any intensification.
A broad low pressure area formed east of Mindanao, Philippines on August 3, after Jebi made landfall over northern Vietnam and dissipated.
[3][6][7] Over the next couple of days the system moved towards the north-northwest before it made landfall in Northern Vietnam during August 7.
[3] In the afternoon of August 7, a teenager named Pham Thanh Son (16 years old, resident of Dang Giang Ward, Ngo Quyen District) heard information about Mangkhut affecting Hai Phong, so he and his three friends took two motorbikes to go watch the storm.
Meanwhile, rainfall totals went up to about 300 mm (12 in) in central Thanh Hóa and northern Hai Phong city, with wind speeds hitting 62–88 km/h (40–55 mph).