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Typhoon Usagi Hits Northern Luzon

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Typhoon Usagi hit northern Luzon on Wednesday night.  At 10:00 p.m. EST on Wednesday the center of Typhoon Usagi was located at latitude 17.6°N and longitude 122.7°E which put the center about 1205 miles (195 km) southeast of Aparri, Philippines.  Usagi was moving toward the northwest at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h).  The minimum surface pressure was 915 mb.

Typhoon Usagi rapidly intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale east of Luzon on Wednesday.  A small circular eye with a diameter of 5 miles (8 km) was at the center of Usagi’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms revolved around the core of Typhoon Usagi.  Storms near the core of Usagi generated strong upper level divergence that pumped large quantities of mass away from the typhoon in all directions.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.  The inner end of a rainband wrapped around the existing eye and eyewall at the center of Usagi’s circulation during Wednesday evening and concentric eyewalls could be forming.

The circulation around Typhoon Usagi was small.  Winds to typhoon force extended out 30 miles (50 km) from the center of Usagi’s circulation.  Winds to tropical storm force extended out 85 miles (135 km) from the center of Typhoon Usagi.

The Hurricane Intensity Index (HII) for Typhoon Usagi was 31.6.  The Hurricane Size Index (HSI) was 9.4 and the Hurricane Wind Intensity Size Index (HWISI) was 41.0 . Typhoon Usagi was similar in size to Hurricane Ida when Ida hit Louisiana in 2021.  Usagi was not as big as Ida was.

Typhoon Usagi will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Usagi toward the northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Usagi will move across northeast Luzon during the next few hours.

Typhoon Usagi will bring strong winds and heavy rain to northern Luzon.  Heavy rain could cause flash floods and mudslides in some locations.  Usagi could cause a storm surge of up to 13 feet ( 4 meters) on the coast of northeastern Luzon.  The area likely to be hit by Usagi was just hit by Typhoon Toraji a few days ago.  Typhoon Usagi will complicate recovery efforts in Luzon.

Elsewhere over the Western North Pacific Ocean, former Tropical Storm Toraji weakened to a tropical depression south of Hong Kong, and Tropical Storm Man-yi was moved north of Yap.

At 10:00 p.m. EST on Wednesday the center of Tropical Depression Toraji was located at latitude 21.0°N and longitude 113.9°E which put the center about 90 miles (145 km) south of Hong Kong.  Toraji was moving toward the west-southwest 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 1005 mb.

At 10:00 p.m. EST on Wednesday the center of Tropical Storm Man-yi was located at latitude 11.1°N and longitude 137.0°E which put the center about 120 miles (195 km) north of Yap. Man-yi was moving toward the west-southwest at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 1000 mb.

Tropical Storm Man-yi Forms Southeast of Chuuk

Tropical Storm Man-yi formed southeast of Chuuk on Tuesday.  At 7:00 a.m. EST on Tuesday the center of Tropical Storm Man-yi was located at latitude 4.8°N and longitude 154.2°E which put it about 245 miles (395 km) southeast of Chuuk.  Man-yi was moving toward the west at 11 m.p.h. (17 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 Storm Watch was issued for Guam and Rota.  Tropical Storm Warnings were in effect for Chuuk Lagoon, Lukunor, Losap, Fananu, Ulul, Pulawat and Satawal.  Typhoon Watches were issued for Faraulep and Pulawat.

Tropical Depression 34W exhibited greater organization on satellite imagery and the Japan Meteorological Agency designated the system as Tropical Storm Man-yi.  More thunderstorms developed near the center of circulation.  The strongest thunderstorms were occurring in a band west of the center.  Other bands of showers and thunderstorms were developing around Tropical Storm Man-yi.  Storms near the center of circulation were generating upper level divergence which was pumping mass away to the west of the tropical storm.

Tropical Storm Man-yi will move through an environment favorable for intensification.  Man-yi will move over water where the Sea Surface Temperature is near 29°C.  It will move south of an upper level ridge.  The ridge will produce easterly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification.  Tropical Storm Man-yi will intensify and it could strengthen into a typhoon in a day or two.

The upper level ridge will steer Tropical Storm Man-yi toward the west-northwest during the next 12 to 24 hours.  A weakness is forecast to develop in the ridge, which would allow Man-yi to move more toward the northwest.  On its anticipated track Tropical Storm Man-yi will move near Chuuk in 12 to 24 hours.  It will bring gusty winds and drop heavy rain.  Man-yi could be southeast of Guam in 36 to 48 hours.

Elsewhere over the Western North Pacific Ocean Tropical Depression 33W was dropping rain over parts of the central Philippines and Tropical Depression Toraji was moving over the Gulf of Thailand.  At 4:00 a.m. EST on Tuesday the center of Tropical Depression 33W was located at latitude 10.9°N and longitude 126.8°E which put it about 160 miles (260 km) east-southeast of Tacloban, Philippines.  It was moving toward the west-northwest at 13 m.p.h. (20 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 1004 mb.

At 4:00 a.m. EDT the center of Tropical Depression Toraji was located at latitude 8.1°N and longitude 101.1°E which put it about 100 miles (160 km) east of Hua Sai, Malaysia.  Toraji was moving toward the west-southwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1002 mb.