Typhoon Gaemi strengthened to the equivalent of a major hurricane east of Taiwan on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Typhoon Gaemi was located at latitude 23.1°N and longitude 123.2°E which put the center about 200 miles (325 km) southeast of Taipei, Taiwan.  Gaemi was moving toward the northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (265 km/h).  The minimum surface pressure was 948 mb.

Typhoon Gaemi rapidly intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale east of Taiwan on Tuesday.  A small circular eye with a diameter of 6 miles (10 km) formed at the center of Gaemi’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storm.  Bands of showers and thunderstorms were revolving around the core of Typhoon Gaemi.  Storms near the core generated strong upper level divergence that pumped mass away from the typhoon.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Typhoon Gaemi was large.  Winds to typhoon force extended out 100 miles (160 km) from the center of Gaemi’s circulation.  Winds to tropical storm force extended out 345 miles (555 km) from the center of Typhoon Gaemi.

The Hurricane Intensity Index (HII) for Typhoon Gaemi was 28.3.  The Hurricane Size Index (HSI) was 31.0 and the Hurricane Wind Intensity Size Index (HWISI) was 59.3.  Typhoon Gaemi was similar in size to Hurricane Wilma when Wilma hit South Florida in 2005.  Gaemi is stronger than Wilma was when it hit South Florida.

Typhoon Gaemi will move through an environment favorable for intensification during the next 12 hours.  Gaemi will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the axis of an upper level ridge over the Western North Pacific Ocean.  The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear.  Typhoon Gaemi could continue to intensify during the next 12 hours.

Typhoon Gaemi will move around the western part of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Typhoon Gaemi toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Gaemi will approach the coast of northeastern Taiwan in 12 hours.

Typhoon Gaemi will bring very strong winds and torrential rain to Taiwan.  Gaemi will be capable of causing extensive severe damage.  Heavy rain is likely to cause widespread flash floods.  Typhoon Gaemi will also be capable of causing a storm surge of up to 13 feet (4 meters) along the east coast of Taiwan.

Typhoon Gaemi will also bring strong winds and heavy rain to the southern Ryukyu Islands.  The strongest part Gaemi’s circulation will pass southwest of the Ryukyu Islands, but the typhoon is likely to some wind damage.  Heavy rain could cause flash floods in some locations.

Typhoon Gaemi will move toward the east coast of China after is crosses northern Taiwan.  Gaemi could approach the coast of China in less than 36 hours.  Typhoon Gaemi will weaken when it moves over Taiwan, but Gaemi could still be a typhoon when it reaches China.

Elsewhere, former Tropical Storm Prapiroon weakened to a tropical depression over northern Vietnam.  At 11:00 a.m. EDT on Tuesday the center of Tropical Depression Prapiroon was located at latitude 22.0°N and longitude 107.0°E which put the center about 25 miles (40 km) northeast of Lang Son, Vietnam.  Prapiroon was moving toward the north-northwest at 5 m.p.h. (8 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 994 mb.