Typhoon Koguma intensified to the equivalent of a major hurricane east of the Northern Marianas on Friday.  At 11:00 a.m. EDT on Friday the center of Typhoon Koguma was located at latitude 20.5°N and longitude 153.5°E which put the center about 640 miles (1035 km) east-northeast of Saipan.  Koguma was moving toward the west-northwest at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (235 km/h).  The minimum surface pressure was 961 mb.

Typhoon Koguma intensified to the equivalent of a major hurricane on Friday as it was completing an eyewall replacement cycle.  A new larger eye was forming at the center of Koguma’s circulation.  Bands of showers and thunderstorms were revolving around the center of Typhoon Koguma.  Storms near the center of Koguma generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

Even though Typhoon Koguma was completing an eyewall replacement cycle, the circulation around Koguma was still small for a typhoon over the Western North Pacific Ocean.  Winds to typhoon force extended out 45 miles (75 km) from the center of Koguma’s circulation.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Typhoon Koguma.

The Hurricane Intensity Index (HII) for Typhoon Koguma is 20.6.  The Hurricane Size Index (HSI) is 16.2 and the Hurricane Wind Intensity Size Index (HWISI) is 36.8.  Typhoon Koguma is similar in size and intensity to Hurricane Delta when Delta hit Louisiana in 2020.

Typhoon Koguma will move through an environment that will be favorable for intensification during the next 24 hours.  Koguma will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southwestern part of an upper level ridge that is over the Central North Pacific Ocean.  The upper level ridge will produce southeasterly winds that will blow toward the top of Koguma’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Typhoon Koguma will intensify during the next 24 hours.

Typhoon Koguma will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Koguma toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Koguma will pass northeast of the Northern Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Nolo continued to weaken gradually far to the southeast of Japan.

At 11:00 a.m. EDT on Friday the center of Tropical Storm Nolo was located at latitude 29.7°N and longitude 147.6°E which put the center about 635 miles (1025 km) southeast of Tokyo, Japan.  Nolo was moving toward the northwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 991 mb.