A tropical depression over the Western North Pacific Ocean east of Mindanao strengthened to Tropical Storm Penha on Wednesday morning. At 10:00 a.m. EST on Wednesday the center of Tropical Storm Penha was located at latitude 8.6°N and longitude 131.0°E which put the center about 330 miles (530 km) west of Tandag, Philippines. Penha was moving toward the west at 13 m.p.h. (21 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.
A tropical depression east of Mindanao strengthened on Wednesday morning and the Japan Meteorological Agency designated the system as Tropical Storm Penha.
The distribution of thunderstorms in Tropical Storm Penha was asymmetrical. Thunderstorms were occurring in bands in the northern and western parts of Penha’s circulation. Bands in the southern and eastern parts of Tropical Storm Penha consisted primarily of showers and lower clouds. Storms near the center of Penha generated upper level divergence that pumped mass away to the north and west of the tropical storm. The removal of mass caused the surface pressure to decrease slowly.
The circulation around Tropical Storm Penha was interacting with a large high pressure system that was south of Japan. The interaction with the high pressure system was causing the distribution of wind speeds in Penha to be asymmetrical. Winds to tropical storm force extended out 100 miles (160 km) in the northern side of Tropical Storm Penha. Winds to tropical storm force only extended out 25 miles (40 km) in the southern half of Penha’s circulation.
Tropical Storm Penha will move through an environment somewhat favorable for intensification during the next 24 hours. Penha will move over water where the Sea Surface Temperatures are near 29°C. It will move under the southwestern part of an upper level ridge over the Western North Pacific Ocean. The upper level ridge will produce southeasterly winds that will blow toward the top of Penha’s circulation. The winds will cause moderate vertical wind shear. The moderate vertical wind shear will inhibit intensification, but the wind shear may not be enough to prevent intensification. Tropical Storm Penha could intensify slowly during the next 24 hours.
Tropical Storm Penha will move around the southern part of the high pressure system that is south of Japan. The high pressure system will steer Penha toward the west during the next 24 hours. On its anticipated track, Tropical Storm Penha will reach Mindanao in 24 hours.
Tropical Storm Penha will bring strong winds and locally heavy rain to Mindanao and the rest of the southern Philippines. Heavy rain could cause flash floods in some locations.