Former Tropical Storm Neoguri strengthened into a typhoon south of Okinawa on Saturday and Tropical Storm Bualoi prompted watches for the Marianas.  At 11:00 p.m. EDT on Saturday the center of Typhoon Neoguri was located at latitude 23.9°N and longitude 128.1°E which put it about 200 miles (320 km) south of Okinawa.  Neoguri was moving toward the north-northeast at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 965 mb.

Typhoon Neoguri strengthened rapidly on Saturday.  An eye formed at the center of circulation and a ring of strong thunderstorms surrounded the eye.  The strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Neoguri.  There were more bands of thunderstorms in the northern half of the typhoon.  The circulation around Typhoon Neoguri was small.  Winds to typhoon force extended out 20 miles (30 km) from the center of circulation.  Winds to tropical storm force extended out 85 miles (135 km) from the center.

Typhoon Neoguri will move through an environment unfavorable for intensification during the next several days.  Neoguri will move over water where the Sea Surface Temperature is near 28°C.  So, there will be enough energy in the ocean to support intensification.  However, an upper level trough over China will produce southwesterly winds which will blow toward the top of Typhoon Neoguri.  Those winds will produce moderate vertical wind shear and the shear will be strong enough to cause Neoguri to weaken.  Since the circulation around the typhoon is small, it could weaken more rapidly if the upper level winds get stronger.

The upper level trough over China will steer Typhoon Neoguri toward the northeast during the next few days.  On its anticipated track Neoguri will pass east of the Ryukyu Islands including Okinawa during the next 36 hours.  It could approach Honshu in about 48 hours.  Typhoon Neoguri will likely be a tropical storm by the time it approaches Honshu.

Elsewhere over the Western North Pacific Ocean, former Tropical Depression 22W rapidly strengthened into Tropical Storm Bualoi.  Bualoi had almost strengthened into a typhoon by Saturday evening.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Bualoi was located at latitude 11.8°N and longitude 150.8°E which put it about 455 miles (730 km) east of Guam.  Bualoi was moving toward the west-northwest at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 985 mb.

Typhoon Watches were in effect for Rota, Tinian and Saipan.  A Tropical Storm Watch was in effect for Guam.

The circulation around Tropical Storm Bualoi organized quickly on Saturday.  The inner end of a rainband wrapped around the center of circulation.  Microwave satellite images indicated that an eye could be forming.  Bands of showers and thunderstorms were revolving around the core of Bualoi.  Storms near the core were generating upper level divergence which was pumping mass away from the tropical storm.  Winds to tropical storm force extended out about 90 miles (145 km) from the center of circulation.

Tropical Storm Bualoi will move through an environment favorable for intensification during the next several days.  Bualoi will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Bualoi will strengthen into a typhoon on Sunday and it could eventually intensify into the equivalent of a major hurricane.

Tropical Storm Bualoi will move south of a high pressure system over the Western North Pacific Ocean.  The high will steer Bualoi toward the west-northwest during the next day or two.  On its anticipated track Tropical Storm Bualoi could reach the Marianas in 36 hours.  Bualoi will very likely be a typhoon when it reaches the Marianas.  The center of Bualoi could pass near Tinian and Saipan.  It could be near Iwo To in about four days.