Typhoon Saola continued to churn over the Western North Pacific Ocean east of Luzon on Sunday. At 11:00 p.m. EDT on Sunday the center of Typhoon Saola was located at latitude 17.0°N and longitude 124.4°E which put it about 200 miles (320 km) east-southeast of Aparri, Philippines. Saola was moving toward the northeast at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h). The minimum surface pressure was 941 mb.

Microwave satellite images showed that the inner end of a rainband was wrapping around the existing eye and eyewall at the center of Typhoon Saola. If the inner end of the rainband wraps completely around the existing eye and eyewall, then a second, larger outer eyewall would form. The formation of two concentric eyewalls would mark the start of an eyewall replacement cycle. An eyewall replacement cycle would cause Typhoon Saola to weaken.

There was still a small circular eye at the center of Typhoon Saola. The small eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Storms near the center of Saola’s circulation generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Saola was small. Winds to typhoon force extended out 20 miles (30 km) from the center of Saola’s circulation. Winds to tropical storm force extended out 90 miles (145 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Saola was 25.1. The Hurricane Size Index (HSI) was 6.9 and the Hurricane Wind Intensity Size Index (HWISI) was 32.0. Typhoon Saola was similar in size and intensity to Hurricane Dennis when Dennis hit Northwest Florida in 2005.

Typhoon Saola will move through an environment favorable for intensification during the next 24 hours. Saola will move over water where the Sea Surface Temperatures are near 30°C. It will move through a region where the upper level ridge winds are weak and there will be little vertical wind shear. However, an eyewall replacement cycle is likely to cause Typhoon Saola to weaken during the next 24 hours.

Typhoon Saola will move around the southwestern side of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Saola back toward the north during the next 24 hours. On its anticipated track, Typhoon Saola will move parallel to the coast of northeastern Luzon. Saola could move toward southern Taiwan later this week.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Damrey was passing east of Japan. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Damrey was located at latitude 38.9°N and longitude 145.3°E which put it about 225 miles (360 km) southeast of Misawa, Japan. Damrey was moving toward the north-northeast at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h). The minimum surface pressure was 979 mb.