A tropical depression formed southwest of the Marianas on Monday morning. At 7:00 a.m. EST on Monday the center of Tropical Depression 27W was located at latitude 11.8°N and longitude 141.1°E which put it about 270 miles (435 km) west-southwest of Guam. The tropical depression was moving toward the west-northwest at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1003 mb.
The circulation around a low pressure system west-southwest of Guam exhibited more organization on Monday morning and the Japan Meteorological Agency designated the system as a tropical depression. The circulation around Tropical Depression 27W was gradually becoming more organized. A distinct low level center of circulation was evident on conventional and microwave satellite images. More thunderstorms were beginning to develop near the center of circulation. Storms near the center began to generate upper level divergence that pumped mass away from the tropical depression. Additional thunderstorms were forming in bands revolving around the center of the depression.
Tropical Depression 27W will move through an environment favorable for intensification during the next 24 hours. The tropical depression will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the western part of the axis of an upper level ridge centered east of the Marianas. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Tropical Depression 27W will strengthen gradually and it is likely to intensify to a tropical storm during the next 24 hours.
Tropical Depression 27W will move around the southwestern part of a high pressure system over the Western North Pacific Ocean during the next 24 hours. The high pressure system will steer the tropical depression toward the west-northwest during the next day or so. On its anticipated track Tropical Depression 27W will move farther away from the Marianas. It will pass north of Yap.