Typhoon Hagibis Strengthens to Equivalent of Cat. 5 Hurricane over Northern Marianas

Typhoon Hagibis strengthened to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale over the Northern Marianas on Monday.  At 5:00 p.m. EDT on Monday the center of Typhoon was located at latitude 16.8°N and longitude 144.8°E which put it about 195 miles (305 km) north-northwest of Guam.  Hagibis was moving toward the west-northwest at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (305 km/h).  The minimum surface pressure was 915 mb.

Typhoon Hagibis rapidly intensified into the equivalent of a Category 5 hurricane on Monday.  A small, pinhole eye was surrounded by a ring of strong thunderstorms.  The strongest winds were occurring in that ring of storms.  A rainband appeared to be wrapping around the original eye and eyewall and an eyewall replacement cycle could be underway.  The start of an eyewall replacement cycle may have ended the period of rapid intensification.  Bands of showers and thunderstorms were revolving around the core of Typhoon Hagibis.  Storms around the core were generating strong upper level divergence which was pumping mass away from the typhoon.

The apparent beginning of an eyewall replacement cycle produced an increase in the size of the circulation around Typhoon Hagibis.  Winds to typhoon force extended out 80 miles (130 km) from the center of circulation.  Winds to tropical storm force extended out about 250 miles (400 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Hagibis was 35.0.  The Hurricane Size Index (HSI) was 27.8 and the Hurricane Wind intensity Size Index (HWISI) was 62.8.  Hagibis was capable of causing catastrophic damage.

The center of Typhoon Hagibis passed north of Tinian and Saipan.  Hagibis would have produced very strong winds on some of the Northern Marianas.  The strongest winds would have occurred between Saipan and Alamagan.  Typhoon Hagibis also dropped heavy rain over Saipan, Tinian, Rota and Guam.

Typhoon Hagibis will remain in an environment very favorable for strong typhoons during the next 24 to 36 hours.  Hagibis will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Hagibis is likely to weaken, while the inner eyewall dissipates and the outer eyewall becomes the part of the typhoon with the strongest winds.  Hagibis could strengthen again if the outer eyewall begins to contract.  An eyewall replacement cycle would increase the size of the circulation.

Typhoon Hagibis will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean.  The ridge will steer Hagibis toward the northwest during the next several days.  Typhoon Hagibis will move toward the northeast after it moves around the western of the high pressure system.  On its anticipated track Typhoon Hagibis could approach the coast of Honshu near Tokyo by the end of this week.

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