Typhoon Nepartak intensified rapidly on Tuesday and it is now the equivalent of a major hurricane.  At 11:00 a.m. EDT on Tuesday the center of Typhoon Nepartak was located at latitude 17.6°N and longitude 132.7°E which put it about 945 miles (1525 km) east-southeast of Taipei, Taiwan.  Nepartak was moving toward west-northwest at 21 m.p.h. (34 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. (270 km/h).  The minimum surface pressure was 933 mb.

Tyyphoon Nepartak is the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  The Hurricane Intensity Index (HII) for Nepartak is 28.3.  The Hurricane Size Index (HSI) is 16.6 and the Hurricane Wind Intensity Size Index (HWISI) is 44.9.  These indices mean that Nepartak is capable of causing regionalized significant damage.

Typhoon Nepartak is very well organized.  It has a well formed eye, which is surround by a ring of strong thunderstorms.  Additional spiral bands of thunderstorms are rotating around the core of the circulation.  Nepartak is generating strong upper level divergence which is pumping out a lot of mass and is allowing the surface pressure to decrease rapidly.

Typhoon Nepartak is in an environment that is favorable for further intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 31°C.  The upper level winds are weak and there is very little vertical wind shear.  Nepartak could intensify into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale during the next 24 to 36 hours.  If one of the rainbands wraps around the existing eye, then concentric eyewalls could form.  If concentric eyewalls develop, then an ensuing eyewall replacement cycle could cause fluctuations in the intensity of Typhoon Nepartak.

A subtropical ridge northeast of Nepartak is steering the typhoon toward the west-northwest and that general motion is expected to continue for another day or two.  On its anticipated track Typhoon Nepartak could be very near the southernmost islands of Japan and the coast of Taiwan in 36 to 48 hours.  It is likely to be a strong typhoon at that time.  Nepartak could cause significant wind damage.  It could also produce heavy rain that could lead to flash floods and mudslides.