Tag Archives: Hong Kong

Tropical Storm Man-yi Brings Gusty Winds to Guam

Tropical Storm Man-yi brought gusty winds to Guam on Tuesday.  At 4:00 p.m. EST on Tuesday the center of Tropical Storm Man-yi was located at latitude 12.5°N and longitude 144.4°E which put the center about 40 miles (65 km) southeast of Guam.  Man-yi was moving toward the southwest at 18 m.p.h. (30 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 994 mb.

Tropical Storm Warnings were in effect for Guam, Rota, Tinian, and Saipan.

Tropical Storm Man-yi brought gusty wind to Guam and the Marianas on Tuesday.  A weather station at the Guam International Airport reported a sustained wind speed of 30 m.p.h. (50 km/h) and a wind gust of 48 m.p.h. (77 km/h) on Tuesday.

The circulation around Tropical Storm Man-yi was somewhat disorganized.  There were not many thunderstorms near the center of Man-yi’s circulation.  Thunderstorms were occurring in bands in the southern side of the center of Tropical Storm Man-yi.  Bands in the northern side of Man-yi’s circulation consisted primarily of showers and lower clouds.

The circulation around Tropical Storm Man-yi was small.  Winds to tropical storm force extended out 85 miles (135 km) from the center of Man-yi’s circulation.

Tropical Storm Man-yi will move through an environment somewhat favorable for intensification during the next 24 hours.  Man-yi will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the southern side of an upper level ridge over the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Man-yi’s circulation.  Those winds will cause some vertical wind shear. The wind shear will inhibit intensification, but the shear may not be enough to prevent intensification. Tropical Storm Man-yi could intensify during the next 24 hours.

Tropical Storm Man-yi will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Man-yi toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Man-yi will move away from the Marianas.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Usagi strengthened east of the Philippines, Tropical Depression Yinxing moved inland over Vietnam, and Tropical Storm Toraji was spinning over the South China Sea southeast of Hong Kong.

At 4:00 p.m. EST on Tuesday the center of Tropical Storm Usagi was located at latitude 15.0°N and longitude 128.3°E which put the center about 530 miles (850 km) east of Manila, Philippines.  Usagi was moving toward the west at 17 m.p.h. (28 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 987 mb.

At 10:00 a.m. EST on Tuesday the center of Tropical Depression Yinxing was located at latitude 14.0°N and longitude 108.2°E which put the center about 145 miles (235 km) south of Da Nang, Vietnam.  Yinxing was moving toward the west at 9 m.p.h. (15 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 1004 mb.

At 4:00 p.m. EST on Tuesday the center of Tropical Storm Toraji was located at latitude 20.1°N and longitude 116.8°E which put the center about 245 miles (395 km) southeast of Hong Kong.  Toraji was moving toward the west-northwest at 5 m.p.h. (8 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 997 mb.

Tropical Storm Toraji Rapidly Develops East of the Philippines

Tropical Storm Toraji rapidly developed over the Western North Pacific Ocean east of the Philippines on Saturday.  At 4:00 p.m. EST on Saturday the center of Tropical Storm Toraji was located at latitude 15.1°N and longitude 127.7°E which put the center about 495 miles (795 km) east of Manila, Philippines.  Toraji was moving toward the west at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 990 mb.

A low pressure system over the Western North Pacific Ocean east of the Philippines strengthened rapidly on Saturday and the Japan Meteorological Agency designated the system as Tropical Storm Toraji.  The circulation around Tropical Storm Toraji organized quickly on Saturday.  Bands of showers and thunderstorms were revolving around the center of Toraji’s circulation.  Storms near the center of Toraji generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the surface pressure to decrease.

The circulation around Tropical Storm Toraji was small.  Winds to tropical storm force extended out 65 miles (105 km) from the center of Toraji’s circulation.

Tropical Storm Toraji will move through an environment favorable for intensification during the next 24 hours.  Toraji will move over water where the Sea Surface Temperatures are near 30°C.  It will move under axis of an upper level ridge over the Western North Pacific Ocean.  The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear.  Tropical Storm Toraji will intensify during the next 24 hours.  Toraji could intensify rapidly at times.  Tropical Storm Toraji is likely to strengthen to a typhoon on Sunday.

Tropical Storm Toraji will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Toraji toward the west-northwest during the next 24 hours.  On its anticipated track Tropical Storm Toraji will approach Luzon in a little over 24 hours.

Tropical Storm Toraji is likely to be a typhoon when it reaches northern Luzon.  Toraji will bring strong winds and locally heavy rain to northern Luzon.  Heavy rain is likely to cause flash floods and mudslides.  Northern Luzon is trying to recover from two recent typhoons.  Typhoon Toraji is likely to seriously disrupt those recovery activities.

Elsewhere over the Western North Pacific Ocean, Typhoon Yinxing passed south of Hong Kong and Tropical Storm Man-yi formed east of the Marianas.

At 4:00 p.m. EST on Saturday the center of Typhoon Yinxing was located at latitude 19.1°N and longitude 113.1°E which put the center about 220 miles (360 km) south-southwest of Hong Kong.  Yinxing was moving toward the west-northwest at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 960 mb.

At 4:00 p.m. EST on Saturday the center of Tropical Storm Man-yi was located at latitude 16.1°N and longitude 156.1°E which put the center about 720 miles (1160 km) east of Saipan.  Man-yi was moving toward the northwest at 25 m.p.h. (40 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 999 mb.

Typhoon Yinxing Spins Over the South China Sea

Typhoon Yinxing was spinning over the South China Sea on Friday afternoon.  At 4:00 p.m. EST on Friday the center of Typhoon Yinxing was located at latitude 18.7°N and longitude 115.4°E which put the center about 275 miles (445 km) south-southeast of Hong Kong.  Yinxing was moving toward the west at 13 m.p.h. (20 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. (230 km/h).  The minimum surface pressure was 969 mb.

Typhoon Yinxing was the equivalent of a major hurricane on Friday afternoon as it spun over the South China Sea.  A circular eye with a diameter of 22 miles (35 km) was that the center of Typhoon Yinxing.  A ring of thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Yinxing’s circulation.  Storms near the core of Yinxing generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Yinxing was a little smaller on Friday afternoon.  Winds to typhoon force extended out 50 miles (80 km) from the center of Yinxing’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Typhoon Yinxing.

The Hurricane Intensity Index (HII) for Typhoon Yinxing was 20.6. The Hurricane Size Index (HSI) was 18.1 and the Hurricane Wind Intensity Size Index (HWISI) was 38.7.  Typhoon Yinxing was similar in intensity to Hurricane Delta when Delta hit Louisiana in 2020.  Yinxing is bigger than Delta was.

Typhoon Yinxing will move through an environment that will become unfavorable for intensification during the next 24 hours.  Yinxing will move over water where the Sea Surface Temperatures are near 29°C.  It will move under axis of an upper level ridge over the Western North Pacific Ocean.  The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear.  However, a high pressure system over China will circulate drier air toward the northwestern part of Typhoon Yinxing.  The drier air will begin to be pulled into the northwestern part of Yinxing’s circulation.  The drier air will cause the thunderstorms in the part of Typhoon Yinxing.  The drier air is likely to cause Typhoon Yinxing to weaken during the next 24 hours.

Typhoon Yinxing will move around the southern part of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Yinxing toward the west during the next 24 hours.  On its anticipated track, Typhoon Yinxing will move pass south of Hong Kong during the next 24 hours.

Typhoon Yagi Passes South of Hong Kong

Powerful Typhoon Yagi passed south of Hong Kong on Thursday.  At 5:00 p.m. EDT on Thursday the center of Typhoon Yagi was located at latitude 19.3°N and longitude 112.5°E which put the center about 230 miles (370 km) south-southwest of Hong Kong.  Yagi was moving toward the west at 12 m.p.h. (19 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 923 mb.

The inner end of a rainband wrapped around the original eye and eyewall at the core of Typhoon Yagi and concentric eyewalls formed.  The formation of concentric eyewalls ended the intensification of Typhoon Yagi, but Yagi was still the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.

A circular eye with a diameter of 23 miles (37 km) was at the center of Yagi’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  A second outer ring of thunderstorms surrounded the inner eyewall.  Bands of showers and thunderstorms were revolving around the core of Typhoon Yagi.  Storms near the core of Yagi generated upper level divergence that pumped mass away from the typhoon.

The formation of concentric eyewalls caused the size of Typhoon Yagi’s circulation to increase.  Winds to typhoon force extended out 90 miles (145 km) from the center of Yagi’s circulation.  Winds to tropical storm force extended out 205 miles (330 km) from the center of Typhoon Yagi.

The Hurricane Intensity Index (HII) for Typhoon Yagi was 31.6.  The Hurricane Size Index (HII) was 24.8 and the Hurricane Wind Intensity Size Index (HWISI) was 56.4.  Typhoon Yagi was similar in intensity to Hurricane Laura when Laura hit southwest Louisiana in 2020.  Yagi is bigger than Laura was.

Typhoon Yagi will move through an environment that will be favorable for intensification during the next 12 hours.  Yagi will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge over the South China Sea.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Even though Typhoon Yagi will move through a favorable environment, the concentric eyewalls may prevent Yagi from intensifying.  If the inner eyewalls weakens, then Typhoon Yagi could weaken as well.  If the inner eyewall remains intact, then Typhoon Yagi could intensify during the next few hours.

Typhoon Yagi will move around the southern part of a high pressure system over China.  The high pressure system will steer Yagi toward the west during the next 24 hours.  On its anticipated track, the center of Typhoon Yagi will reach northeastern Hainan in 12 hours.  Typhoon Yagi is likely to be the equivalent of a major hurricane when it reaches Hainan.

Typhoon Yagi will bring strong winds and heavy rain to Hainan.  Yagi will be capable of causing major damage in Hainan.  Heavy rain is likely to cause floods in some locations.  Typhoon Yagi could also cause a storm surge of up to 14 feet (4.3 meters) along the coast of northeastern Hainan.  Yagi will also bring strong winds and heavy rain to southwestern Guangdong and Guangxi.

 

Typhoon Yagi Rapidly Intensifies to Equivalent of a Major Hurricane

Typhoon Yagi rapidly intensified to the equivalent of a major hurricane over the South China Sea on Wednesday.  At 11:00 a.m. EDT on Wednesday the center of Typhoon Yagi was located at latitude 19.2°N and longitude 116.6°E which put the center about 275 miles (445 km) southeast of Hong Kong.  Yagi was moving toward the west at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 968 mb.

Typhoon Yagi rapidly intensified to the equivalent of a majoro hurricane on Wednesday.  A circular eye was visible at the center of Yagi’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 were revolving around the core of Typhoon Yagi.  Storms near the core generated upper level divergence that pumped large amounts of mass away from the typhoon.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Typhoon Yagi increased in size as Yagi intensified rapidly.  Winds to typhoon force extended out 60 miles (95 km) from the center of Yagi’s circulation.  Winds to tropical storm force extended out 140 miles (220 km) from the center of Typhoon Yagi.

The Hurricane Intensity Index (HII) for Typhoon Yagi was 23.6.  The Hurricane Size Index (HSI) was 16.2 and the Hurricane Wind Intensity Size Index (HWISI) was 39.8.  Typhoon Yagi was similar in intensity to Hurricane Dennis when Dennis hit Florida in 2005.  Yagi is larger than Dennis was.

Typhoon Yagi will move through an environment that will be very favorable for intensification during the next 24 hours.  Yagi will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge over the South China Sea. The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Yagi will intensify during the next 24 hours.  Yagi could continue to intensify rapidly during the next few hours.  If the inner end of rainband wraps around the eye and eyewall in the core of Yagi’s circulation, then an eyewall replacement cycle could cause Typhoon Yagi to weaken.

Typhoon Yagi will move around the southern part of a high pressure system over China.  The high pressure system will steer Yagi toward the west-northwest during the next 24 hours. On its anticipated track, the center of Typhoon Yagi will be south of Hong Kong in 24 hours.  Yagi will approach Hainan and the coast of southern China in 36 hours.  Typhoon Yagi is likely to be the equivalent of a major hurricane when it approaches Hainan and the coast of southern China.

Typhoon Yagi will bring strong winds and heavy rain to southern China later this week.  Yagi will bring strong winds and heavy rain to Guangdong, Guangxi and Hainan.  Heavy rain is likely to cause floods in some locations.

 

Yagi Strengthens to a Typhoon Southeast of Hong Kong

Former Tropical Storm Yagi strengthened to a typhoon southeast of Hong Kong on Tuesday evening.  At 11:00 p.m. EDT on Tuesday the center of Typhoon Yagi was located at latitude 19.1°N and longitude 117.5°E which put the center about 315 miles (510 km) southeast of Hong Kong.  Yagi was moving toward the west-northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 977 mb.

Former Tropical Storm Yagi intensified rapidly to a typhoon after it moved over the South China Sea.  A circular eye formed at the center of Yagi’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 were revolving around the core of Typhoon Yagi.  Storms near the core generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The circulation around Typhoon Yagi was symmetrical.  Winds to typhoon force extended out 35 miles (55 km) from the center of Yagi’s circulation.  Winds to tropical storm force extended out 110 miles (185 km) from the center of Typhoon Yagi.

Typhoon Yagi will move through an environment that will be very favorable for intensification during the next 24 hours.  Yagi will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge over the South China Sea. The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Yagi will intensify during then next 24 hours.  Yagi could intensify rapidly to the equivalent of a major hurricane.

Typhoon Yagi will move around the southern part of a high pressure system over China.  The high pressure system will steer Yagi toward the west-northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Yagi will be south of Hong Kong in 36 hours.  Yagi will approach Hainan and the coast of southern China in 48 hours.  Typhoon Yagi could be the equivalent of a major hurricane when it approaches Hainan and the coast of southern China.

 

 

Maliksi Drops Rain on Southeastern China

Former Tropical Storm Maliksi dropped rain on parts of southeastern China on Saturday. At 5:00 p.m. EDT on Saturday the center of Tropical Depression Maliksi was located at latitude 23.0°N and longitude 112.0°E which put it about 125 miles (200 km) west of Guangzhou, China. Maliksi was moving toward the north-northeast at 12 m.p.h. (19 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 1002 mb.

Former Tropical Storm Maliksi weakened to a tropical depression after it made landfall on the coast of southern China west of Hong Kong late on Friday. Thunderstorms were still occurring in bands in the eastern and southern parts of Maliksi’s circulation. Some of those thunderstorms were dropping heavy rain on parts of southeastern China. Heavy rain was falling in parts of Guangdong. Prolonged heavy rain could cause floods in some locations.

The circulation around Tropical Depression Maliksi will continue to weaken as it moves over southeastern China. Maliksi could dissipate by the end of the weekend.

Tropical Storm Maliksi Forms Southwest of Hong Kong

Tropical Storm Maliksi formed over the South China Sea southwest of Hong Kong on Friday. At 11:00 a.m. EDT on Friday the center of Tropical Storm Maliksi was located at latitude 21.4°N and longitude 111.6°E which put it about 185 miles (300 km) west-southwest of Hong Kong. Maliksi was moving toward the north-northwest at 8 m.p.h. (13 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 998 mb.

A low pressure system over the South China Sea southwest of Hong Kong strengthened on Friday and the Japan Meteorological Agency designated the system as Tropical Storm Maliksi. The distribution of thunderstorms in Tropical Storm Maliksi was asymmetrical. Thunderstorms were occurring in bands in the southern half of Maliksi’s circulation. Bands in the northern half of the circulation consisted primarily of showers and lower clouds. Storms near the center of circulation generated upper level divergence that pumped mass away to the south of the tropical storm.

The distribution of wind speeds around Tropical Storm Maliksi was also asymmetrical. Winds to tropical storm force extended out 120 miles (195 km) in the southeastern part of Maliksi’s circulation. Winds to tropical storm force only extended out 60 miles (95 km) in the northwestern side of Maliksi.

Tropical Storm Maliksi will move through an environment somewhat favorable for intensification during the next few hours. Maliksi will move over water where the Sea Surface Temperatures are near 29°C. It will move under the eastern part of an upper level ridge over China. The ridge will produce northerly winds that will blow toward the top of Maliksi’s circulation. Those winds will also cause moderate vertical wind shear. The wind shear will inhibit intensification. Tropical Storm Maliksi could intensify a little during the next few hours.

Tropical Storm Maliksi will move around the western side of a high pressure system over the Western North Pacific Ocean. The high pressure will steer Maliksi toward the north during the next 24 hours. On its anticipated track, Tropical Storm Maliksi will make landfall in southern China in a few hours. Maliksi will drop heavy rain over parts of southern China. Heavy rain could cause floods in some locations.

Tropical Storm Bolaven Moves Toward the Marianas

Tropical Storm Bolaven moved toward the Marianas on Sunday night. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Bolaven was located at latitude 11.1°N and longitude 149.9°E which put it about 410 miles (660 km) east-southeast of Guam. Bolaven was moving toward the west-northwest at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h). The minimum surface pressure was 992 mb.

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

Tropical Storm Bolaven strengthened on Sunday. The inner end of a rainband wrapped around the center of Bolaven’s circulation. Bands of showers and thunderstorms revolved around the center of circulation. Storms near the center generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 70 miles (100 km) from the center of Bolaven.

Tropical Storm Bolaven will move through an environment favorable for intensification during the next 24 hours. Bolaven will move over water where the Sea Surface Temperatures are near 30°C. It will move under the southern part of an upper level ridge over the Western North Pacific Ocean. The ridge will produce easterly winds that will blow toward the top of Bolaven’s circulation. Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification. Tropical Storm Bolaven is likely to intensify to a typhoon during the next 24 hours.

Tropical Storm Bolaven will move around the southwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Bolaven toward the northwest during the next 24 hours. On its anticipated track Tropical Storm Bolaven will move closer to the Marianas. Bolaven could reach the Marianas in less than 36 hours. Bolaven will very likely be a typhoon when it reaches the Marianas.

Elsewhere over the Western North Pacific Ocean, former Typhoon Koinu made landfall on the coast of China west of Hong Kong on Sunday. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Koinu was located at latitude 21.5°N and longitude 112.9°E which put it about 75 miles (120 km) west-southeast of Hong Kong. Koinu was moving toward the west at 5 m.p.h. (8 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 988 mb.

Typhoon Koinu Lingers Near Hong Kong

Typhoon Koinu lingered over the Western North Pacific Ocean near Hong Kong on Saturday. At 11:00 p.m. EDT on Saturday the center of Typhoon Koinu was located at latitude 21.4°N and longitude 114.4°E which put it about 65 miles (105 km) south-southeast of Hong Kong. Koinu was moving toward the west-northwest at 4 m.p.h. (6 km/h). The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h). The minimum surface pressure was 968 mb.

Typhoon Koinu weakened gradually on Saturday as it lingered near Hong Kong. Since Koinu moved very slowly, the strong winds in the lower atmosphere mixed cooler water to the surface of the ocean. Koinu was unable to extract as much energy from the cooler water and the typhoon weakened. Thunderstorms in Typhoon Koinu did not rise quite as high into the atmosphere.

Even though Typhoon Koinu weakened on Saturday, it still exhibited a well organized circulation. A very small eye was present at the center of Koinu’s circulation. The inner end of a rainband wrapped around the existing eye and eyewall, and concentric eyewalls could be developing. Bands of showers and thunderstorms revolved around the small core of Typhoon Koinu. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The size of the circulation around Typhoon Koinu decreased as Koinu gradually weakened. Winds to typhoon force extended out 25 miles (40 km) from the center of Koinu’s circulation. Winds to tropical storm force extended out 90 miles (145 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Koinu was 16.5. The Hurricane Size Index (HSI) was 8.6. and the Hurricane Wind Intensity Size Index (HWISI) was 25.1.

Typhoon Koinu will move through an environment somewhat unfavorable for intensification during the next 24 hours. Koinu will move over water where the Sea Surface Temperatures are near 27°C. It will move under axis of an upper level ridge over China. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. However, strong winds in the lower atmosphere will continue to mix cooler water to the surface of the ocean. In addition, the circulation around the northern side of Typhoon Koinu could draw in some drier air from China. Typhoon Koinu is likely to continue to weaken gradually during the next 24 hours due to the mix of cooler water to the surface of the ocean.

Typhoon Koinu will move will move around the southern part of a high pressure system over eastern Asia. The high pressure system will steer Koinu slowly toward the west during the next 24 hours. On its anticipated track the center Typhoon Koinu will move south of Hong Kong on Sunday.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 15W strengthened to Tropical Storm Bolaven east-southeast of Guam. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Bolaven was located at latitude 9.6°N and longitude 152.9°E which put it about 630 miles (1020 km) east-southeast of Guam. Bolaven was moving toward the west-northwest at 5 m.p.h. (8 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. Typhoon Watches were in effect for Guam, Rota, Tinian and Saipan.