Tropical Depression 04W formed southwest of Palau on Saturday. At 11:00 p.m. EDT on Saturday the center of Tropical Depression 04W was located at latitude 6.8°N and longitude 133.5°E which put it about 75 miles (120 km) southwest of Palau. It was moving toward the west-northwest at 8 m.p.h. (13 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 Tropical Depression 04W was still organizing on Saturday night. Bands of thunderstorms were revolving around the center of the depression. The strongest rainbands were in the western half of the circulation. Bands on the eastern side of the tropical depression consisted mainly of showers and lower clouds. Storms near the center of circulation began to generate upper level divergence that pumped mass away to the west and north of the depression.
Tropical Depression 04W 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 30°C. It will move under the southern side of an upper level ridge east of the Philippines. The ridge will produce easterly winds which will blow toward the top of the depression. Those winds will cause vertical wind shear. The wind shear will not be enough to prevent intensification, but the shear will limit the rate of intensification. Tropical Depression 04W will likely intensify into a tropical storm during the next 24 hours.
Tropical Depression 04W will move around the western side of a subtropical high pressure system over the Western North Pacific Ocean. The high will steer the tropical depression toward the northwest during the next 48 hours. On its anticipated track Tropical Depression 04W will move farther away from Palau. The tropical depression is forecast to pass east of the Philippines.