Tropical Storm Mulan formed over the South China Sea south of Hing Kong on Tuesday morning. At 5:00 a.m. EDT on Tuesday the center of Tropical Storm Mulan was located at latitude 17.9°N and longitude 112.8°E which put it about 280 miles (450 km) south of Hong Kong. Mulan was moving toward the north at 13 m.p.h. (20 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 996 mb.

A small low pressure system on the eastern side of a much larger low pressure system over the South China Sea south of Hong Kong strengthened on Tuesday morning and the Japan Meteorological Agency designated the system as Tropical Storm Mulan. The circulation around Tropical Storm Mulan was embedded in a larger low pressure system over the South China Sea which had a diameter of 700 miles (1130 km). The distribution of thunderstorms around Mulan was asymmetrical. Thunderstorms were occurring mainly in bands in the eastern half of Mulan’s circulation. Bands in the western half of the circulation consisted primarily of showers and lower clouds. Storms near the center of Mulan’s circulation generated upper level divergence that pumped mass away from the tropical storm.

Tropical Storm Mulan will move through an environment marginally favorable for intensification during the next 24 hours. Mulan will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the eastern side of a broad upper level low over the South China Sea. The upper low will produce southerly winds that will blow toward the top of Mulan’s circulation. The winds at lower levels in the atmosphere will also blow from the south. So, there will be little vertical wind shear. Even though the water will be warm and there will be little vertical wind shear, the fact that Tropical Storm Mulan is a smaller low pressure system embedded in a much larger low pressure system is likely to inhibit intensification.

Tropical Storm Mulan will move around the northeastern part of the larger low pressure system over the South China Sea during the next 24 hours. The larger low pressure system will steer Mulan toward the northwest. On its anticipated track Tropical Storm Mulan could approach the south coast of China near Zhanjiang within 24 hours. Mulan will bring gusty winds and locally heavy rain to parts of southern China. Heavy rain could cause flash floods in some locations.