Typhoon Rai strengthened east of Mindanao on Wednesday morning. At 10:00 a.m. EST on Wednesday the center of Typhoon Rai was located at latitude 9.5°N and longitude 129.3°E which put it about 260 miles (415 km) east of Dinagat, Philippines. Rai was moving toward the west at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h). The minimum surface pressure was 969 mb.

Typhoon Rai continued to intensify during Tuesday night and Wednesday morning. A small circular eye was at the center of Rai’s circulation. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Typhoon Rai. The strongest rainbands were in the western and southern parts of the typhoon. Storms near the core of Rai generated upper level divergence that pumped mass away to the west and north of the typhoon.

The circulation around Typhoon Rai tightened as it intensified. Winds to typhoon force extended out 40 miles (65 km) from the center of Rai. Winds to tropical storm force extended out 125 miles (200 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Rai was 13.9. The Hurricane Size Index (HSI) was 10.0 and the Hurricane Wind Intensity Size Index (HWISI) was 23.9. Typhoon Rai was capable of doing regional serious damage.

Typhoon Rai will move through an environment favorable for intensification during the next 18 hours. Rai 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 over the Western North Pacific Ocean. The ridge will produce easterly winds that will blow toward the top of Typhoon Rai’s circulation. Those winds will cause some vertical wind shear but the wind shear will be too small to prevent intensification. Typhoon Rai will continue to strengthen during the next 18 hours. Rai could undergo a period of rapid intensification

Typhoon Rai will move south of a surface high pressure system over the Western North Pacific Ocean. The high pressure system will steer Rai toward the west-northwest during the next 48 hours. On its anticipated track the center of Typhoon Rai could approach northern Mindanao in 18 hours. Rai will be a typhoon when it reaches the Philippines. Typhoon Rai will bring strong winds and locally heavy rain to northern Mindanao, Siargao Island, Dinagat Island, Samar, Leyte, Cebu, Negros, Bohol and Panay Island. Heavy rain could cause flash floods in some locations. Rai will cause a significant storm surge along coasts where the wind blows the water toward the shore.