Former Tropical Depression 27W strengthened to Tropical Storm Nyatoh west of Guam on Monday night. At 10:00 p.m. EST on Monday the center of Tropical Storm Nyatoh was located at latitude 13.0°N and longitude 138.7°E which put it about 370 miles (600 km) west of Guam. Nyatoh was moving toward the west at 14 m.p.h. (22 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 1000 mb.

The circulation around former Tropical Depression 27W continued to strengthen on Monday night and the Japan Meteorological Agency upgraded the system to Tropical Storm Nyatoh. More thunderstorms developed near the center of circulation and in the bands revolving around the center of Nyatoh. Storms near the center generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 125 miles (200 km) from the center of Tropical Storm Nyatoh.

Tropical Storm Nyatoh will move through an environment mostly favorable for intensification during the next 36 hours. Nyatoh 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. Clockwise flow around a high pressure system centered over eastern Asia could transport drier air toward the northwestern part of Nyatoh’s circulation. The drier air is likely to remain northwest of the core of Tropical Storm Nyatoh during the next 36 hours. Tropical Storm Nyatoh will continue to strengthen and it could intensify to a typhoon during the next 36 hours.

Tropical Storm Nyatoh will move around the southwestern part of a high pressure system over the Western North Pacific Ocean during the next 36 hours. The high pressure system will steer the tropical depression toward the northwest during the next 36 hours. On its anticipated track Tropical Storm Nyatoh will move farther away from the Marianas and Yap.