Tropical Storm Mangkhut developed east of the Marianas on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Mangkhut was located at latitude 13.1°N and longitude 163.2°E which put it about 1275 miles (2060 km) east of Guam.  Mangkhut was moving toward the west at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and three were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 998 mb.

A distinct center of circulation formed in a cluster of thunderstorms east of the Marianas and the Japan Meteorological Agency designated the system as Tropical Storm Mangkhut.  The circulation of Mangkhut was still organizing.  Bands of showers and thunderstorms were developing around Tropical Storm Mangkhut.  There were more thunderstorms on the western side of the circulation.  An upper level ridge north of Mangkhut was producing easterly winds which were blowing toward the top of the circulation.  Those winds were probably the reason why more of the thunderstorms were west of the center of circulation.

Tropical Storm Mangkhut will be moving through an environment favorable for intensification.  Mangkhut will move over water where the Sea Surface Temperature is near 30°C.  It will move south of the upper level ridge, which will cause some vertical wind shear.  However, the shear is not likely to be strong enough to prevent intensification.  Tropical Storm Mangkhut could strengthen into a typhoon by the end of the weekend.

Tropical Storm Mangkhut will move south of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Mangkhut in a general westerly direction.  On its anticipated track Mangkhut could approach the Marianas in about 72 hours.  It is likely to be a typhoon at that time.