Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Typhoon Koinu Rapidly Intensifies to Equivalent of a Major Hurricane

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Typhoon Koinu rapidly intensified to the equivalent of a major hurricane over the Western North Pacific Ocean east-southeast of Taiwan on Sunday night. At 5:00 a.m. EDT on Monday the center of Typhoon Koinu was located at latitude 19.9°N and longitude 126.4°E which put it about 405 miles (650 km) east-southeast of Hengchun, Taiwan. Koinu was moving toward the northwest at 9 m.p.h. (15 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 953 mb.

Typhoon Koinu rapidly intensified to the equivalent of a major hurricane during the past 24 hours. A circular eye with a diameter of 10 miles (16 km) was at the center of Koinu’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 center of Typhoon Koinu. Storms near the center generated upper level divergence that pumped mass away from the typhoon.

The size of the circulation around Typhoon Koinu increased when Koinu rapidly intensified. Winds to typhoon force extended out 50 miles (80 km) from the center of Koinu’s circulation. Winds to tropical storm force extended out 150 miles (240 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Koinu was 22.1. The Hurricane Size Index (HSI) was 17.3 and the Hurricane Wind Intensity Size Index (HWISI) was 39.4.

Typhoon Koinu will move through an environment favorable for intensification during the next 24 hours. Koinu 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 and eastern Asia. The upper level ridge will produce easterly winds that will blow toward the top of Koinu’s circulation. Those winds will cause some vertical wind shear, but the wind shear will not be strong enough to prevent intensification. Typhoon Koinu is likely to intensify during the next 24 hours.

Typhoon Koinu will move around the southern part of a high pressure system over eastern Asia. The high pressure system will steer Koinu toward the northwest during the next 24 hours. On its anticipated track Typhoon Koinu will move closer to Taiwan. Koinu will approach southern Taiwan in 48 hours. Typhoon Koinu is likely to be the equivalent of a major hurricane when it approaches Taiwan. Koinu will bring strong, gusty winds and locally heavy rain to Taiwan. Heavy rain will cause flash floods in some locations.

Koinu Strengthens to a Typhoon

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Former Tropical Storm Koinu strengthened to a typhoon over the Western North Pacific Ocean east-southeast of Taiwan on Sunday morning. At 11:00 a.m. EDT on Sunday the center of Typhoon Koinu was located at latitude 18.6°N and longitude 128.5°E which put it about 570 miles (920 km) east-southeast of Hengchun, Taiwan. Koinu was moving toward the northwest at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 977 mb.

Former Tropical Storm Koinu intensified rapidly during the past 24 hours. The inner end of a rainband wrapped around the center of Typhoon Koinu. A circular eye with a diameter off 17 miles (28 km) developed at the center of Koinu’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 center of Typhoon Koinu, Storms near the center generated upper level divergence that pumped mass away to the west of the typhoon. Winds to typhoon force extended out 20 miles (30 km) from the center of Koinu’s circulation. Winds to tropical storm force extended out 85 miles (135 km) from the center of circulation.

Tropical Storm Koinu will move through an environment favorable for intensification during the next 24 hours. Koinu will move over water where the Sea Surface Temperatures are near 30°C. ‘ It will move under the southeastern part of an upper level ridge centered west of Taiwan. The ridge will produce northeasterly winds that will blow toward the top of Koinu’s circulation. Those winds will cause some vertical wind shear. The wind shear will inhibit intensification, but the shear will not be strong enough to completely stop intensification. Typhoon Koinu will intensify during the next 24 hours. Koinu could strengthen to the equivalent of a major hurricane.

Tropical Storm Koinu will move around the southern part of a high pressure system over eastern Asia. The high pressure system will steer Koinu toward the northwest during the next 24 hours. On its anticipated track Tropical Storm Koinu will move closer to Taiwan. Koinu could approach southern Taiwan in three days. Typhoon Koinu is likely to be the equivalent of a major hurricane when it approaches Taiwan.

Tropical Storm Koinu Forms Southeast of Taiwan

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Tropical Storm Koinu formed over the Western North Pacific Ocean southeast of Taiwan on Friday night. At 5:00 a.m. EDT on Saturday the center of Tropical Storm Koinu was located at latitude 16.0°N and longitude 130.9°E which put it about 850 miles (1730 km) southeast of Taipei, Taiwan. Koinu was moving toward the west-northwest at 11 m.p.h. (17 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 997 mb.

A low pressure system over the Western North Pacific Ocean southeast of Taiwan strengthened on Friday night and the Japan Meteorological Agency designated the system as Tropical Storm Koinu. The distribution of thunderstorms around Tropical Storm Koinu was asymmetrical. Many of the thunderstorms were occurring in bands in the western half of Koinu’s circulation. Bands in the eastern side of Tropical Storm Koinu consisted primarily of showers and lower clouds. Storms near the center of Koinu’s circulation generated upper level divergence that pumped mass away to the west of the tropical storm. Winds to tropical storm force extended out 170 miles (275 km) from the center of circulation.

Tropical Storm Koinu will move through an environment favorable for intensification during the next 24 hours. Koinu 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 Koinu’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will inhibit intensification, but the shear will not be strong enough to completely stop intensification. Tropical Storm Koinu is likely to intensify gradually during the next 24 hours.

Tropical Storm Koinu will move around the southwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Koinu toward the northwest during the next 24 hours. On its anticipated track Tropical Storm Koinu will move closer to Taiwan. Koinu could approach southern Taiwan in four days. It could be a typhoon when it approaches Taiwan.

Tropical Storm Yun-yeung Moves Toward Honshu

Tropical Storm Yun-Yeung moved toward Honshu on Wednesday. At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Yun-yeung was located at latitude 30.2°N and longitude 136.7°E which put it about 430 miles (695 km) south-southwest of Tokyo, Japan. Yun-yeung was moving toward the north-northeast at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 994 mb.

Tropical Storm Yun-yeung consisted primarily of a low level circulation on Wednesday night. The bands revolving around the center of Yun-yeung’s circulation contained primarily showers and lower clouds. A strong upper level trough northwest of Japan produced strong southwesterly winds that blew across the top of Tropical Storm Yun-Yeung. Those winds caused strong vertical wind shear and the winds blew the upper part of Yun-Yeung’s circulation to the northeast of the circulation near the surface . There was a band of thunderstorms near the northern periphery of Tropical Storm Yun-yeung. Winds to tropical storm force extended out 100 miles (160 km) in the eastern side of Yun-Yeung’s circulation. The winds in the western side of Yun-yeung were blowing at less than tropical storm force.

Tropical Storm Yun-yeung will move through an environment unfavorable for intensification of a tropical storm during the next 36 hours. Yun-yeung will move over water where the Sea Surface Temperatures are near 28°C. However, the upper level trough northwest of Japan will continue to cause strong vertical wind shear. The strong vertical wind shear will prevent intensification of Tropical Storm Yun-yeung. Yun-yeung could get a little stronger, if it makes a transition to an extratropical cyclone.

Tropical Storm Yun-yeung will move around the northwestern part of high pressure system over the Western North Pacific. The high pressure system and the upper level trough northwest of Japan will steer Yun-yeung toward the northeast during the next 36 hours. On its anticipated track, Tropical Storm Yun-yeung will approach Tokyo in 36 hours.

Tropical Storm Yun-yeung Forms South of Japan

Tropical Storm Yun-yeung formed over the Western North Pacific Ocean south of Japan on Tuesday night. At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Yun-yeung was located at latitude 26.2°N and longitude 133.6°E which put it about 810 miles (1305 km) south-southwest of Tokyo, Japan. Yun-yeung was moving toward the north at 17 m.p.h. (28 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 Western North Pacific Ocean strengthened on Tuesday and the Japan Meteorological Agency designated the system as Tropical Storm Yun-yeung. More thunderstorms developed near the center of Yun-yeung’s circulation on Tuesday evening, but the distribution of thunderstorms was asymmetrical. Most of the thunderstorms were occurring in bands in the southern half of Tropical Storm Yun-yeung. Bands in the northern half of the circulation consisted primarily of showers and lower clouds. The distribution of wind speeds was also asymmetrical. Winds to tropical storm force extended out 40 miles (65 km) in the eastern side of Yun-yeung’s circulation. The winds in the eastern side of Yun-yeung were blowing at less than tropical storm force.

Tropical Storm Yun-yeung will move through an environment somewhat favorable for intensification during the next 24 hours. Yun-yeung will move over water where the Sea Surface Temperatures are near 28°C. It will move under the eastern side on an upper level ridge south of Japan. The upper level ridge will produce northeasterly winds that will blow toward the top of Yun-yeung’s circulation. Those winds will cause moderate vertical wind shear. The wind shear is already contributing to the asymmetrical distribution of thunderstorms. The vertical wind shear will inhibit intensification, but the shear will probably not be strong enough to prevent Yun-yeung from strengthening. Tropical Storm Yun-yeung is likely to intensify gradually during the next 24 hours.

Tropical Storm Yun-yeung will move around the northwestern part of high pressure system over the Western North Pacific. The high pressure system will steer Yun-yeung toward the north-northeast during the next 24 hours. On its anticipated track, Tropical Storm Yun-yeung will move closer to Honshu. Yun-yeung could be near Tokyo in 48 hours.

Tropical Storm Haikui Makes Landfall near Shantou, China

The center of Tropical Storm Haikui made landfall on the coast of eastern China near Shantou on Monday. At 5:00 p.m. EDT on Monday the center of Tropical Storm Haikui was located at latitude 23.7°N and longitude 117.0°E which put it about 15 miles (20 km) northeast of Shantou, China. Haikui was moving toward the west at 13 m.p.h. (21 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 996 mb.

Former Typhoon Haikui weakened to a tropical storm as it moved across the Taiwan Strait. The lower levels of circulation around Haikui were disrupted by the mountains on Taiwan. The disruption caused Haikui to weaken steadily before it made landfall in China. Many of the bands revolving around the center of Tropical Storm Haikui consisted primarily of showers and lower clouds. There were thunderstorms in a band just to the south of the center of Haikui’s circulation. There were also thunderstorms in a band in the eastern side of Tropical Storm Haikui.

Tropical Storm Haikui will move toward the west over eastern China. Haikui will weaken to a tropical depression as it moves inland. Tropical Storm Haikui will bring gusty winds and isolated heavy rain to eastern Guangdong province.

Typhoon Haikui Moves over the Taiwan Strait

Typhoon Haikui moved over the Taiwan Strait on Sunday night. At 11:00 p.m. EDT on Sunday the center of Typhoon Haikui was located at latitude 23.3°N and longitude 119.6°E which put it about 70 miles (110 km) northwest of Kaohsiung, Taiwan. Haikui was moving toward the west-northwest at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 966 mb.

Typhoon Haikui brought strong winds and heavy rain to Taiwan on Sunday. A weather station at the airport in Taipei (RCTP) reported a sustained wind speed of 35 m.p.h. (55km/h) and a wind gust of 49 m.p.h. (79 km/h). A weather station in Taitung (RCFN) reported a sustained wind speed of 56 m.p.h. (91 km/h) and a wind gust of 87 m.p.h. (140 km/h). A weather station in Kaohsiung (RCKH) reported a sustained wind speed of 39 m.p.h. (63 km/h) and a wind gust of 62 m.p.h. (100 km/h). Bands in the eastern part of Typhoon Haikui were still dropping heavy rain over parts of Taiwan on Sunday night.

The lower levels of the circulation of Typhoon Haikui were disrupted when Haikui moved over the mountains on Taiwan. There was no longer an eye at the center of Haikui’s circulation. The circulation in the middle and upper level of Typhoon Haikui remained relatively intact. Bands of showers and thunderstorms were revolving around the center of Haikui’s circulation. Winds to typhoon force extended out 30 miles (50 km/h) from the center of circulation. Winds to tropical storm force extended out 165 miles (265 km) from the center of Typhoon Haikui.

Typhoon Haikui will move around the southern side of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Haikui toward the west-northwest during the next 24 hours. On its anticipated track, the center of Typhoon Haikui will approach the east coast of China between Shantou and Xiamen within 24 hours.

Typhoon Haikui will move through an environment favorable for intensification during the next 24 hours. Haikui will move over water where the Sea Surface Temperatures are near 30°C. It will move under an upper level ridge centered northwest of Taiwan. The upper level winds are weak in the ridge and the will be little vertical wind shear. Typhoon Haikui may not intensify during the next 24 hours even though it will move through a favorable environment. The lower levels of Haikui’s circulation will gradually reorganize now that the center of circulation is back over water. However, there may not be enough time for an eye to develop again before Haikui reaches the east coast of China. If the inner core of Typhoon Haikui does not develop again, then it will be unlikely to strengthen.

Typhoon Haikui Hits Taiwan

Typhoon Haikui hit Taiwan on Sunday morning. At 5:00 a.m. EDT on Sunday the center of Typhoon Haikui was located at latitude 22.9°N and longitude 121.1°E which put it about 20 miles (30 km) northeast of Taitung, Taiwan. Haikui was moving toward the west at 12 m.p.h. (19 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 947 mb.

The center of Typhoon Haikui made landfall on the southeast coast of Taiwan just to the northeast of Taitung on Sunday morning. Haikui intensified to the equivalent of a major hurricane as it approached the coast of Taiwan. The Hurricane Intensity Index (HII) for Typhoon Haikui was 22.1. The Hurricane Size Index (HSI) was 13.0 and the Hurricane Wind Intensity Size Index (HWISI) was 35.1. Typhoon Haikui was similar in size and intensity to Hurricane Dennis when Dennis hit Northwest Florida in 2005.

Typhoon Haikui brought strong, gusty winds and heavy rain to Taiwan. Winds to typhoon force extended out 40 miles (65 km) from the center of Haikui’s circulation. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation.

The center of Typhoon Haikui will move across southern Taiwan during the next few hours. Haikui’will produce strong, gusty winds in much of Taiwan. Typhoon Haikui is capable of causing regional major damage. Widespread outages of electricity are likely. Heavy rains will cause flash floods, especially near mountains.

The center of Typhoon Haikui will be near Kaohsiung in a few hours. Haikui will weaken as it moves across southern Taiwan. Mountains in Taiwan could will disrupt the circulation in the lower levels of Typhoon Haikui. The circulation in the middle and upper troposphere will remain move relatively intact. Haikui will move over the South China Sea later on Sunday. Typhoon Haikui could approach the coast of China near Shantou in less than 36 hours.

Typhoon Haikui Nears Taiwan

Typhoon Haikui neared Taiwan on Saturday. At 5:00 p.m. EDT on Saturday the center of Typhoon Haikui was located at latitude 22.6°N and longitude 122.7°E which put it about 100 miles (160 km) east-southeast of Taitung, Taiwan. Haikui was moving toward the west at 13 m.p.h. (21 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 958 mb.

Typhoon Haikui intensified as it neared Taiwan on Saturday. A small circular eye was at the center of Haikui’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 Haikui. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The Taiwan Central Weather Bureau’s radar images indicated that Typhoon Haikui was very symmetrical. Winds to typhoon force extended out 35 miles (55 km) from the center of Haikui’s circulation. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Haikui was 17.8. The Hurricane Size Index (HSI) was 9.7 and the Hurricane Wind Intensity Size Index (HWISI) was 27.5. Typhoon Haikui was similar in size and intensity to Hurricane Zeta when Zeta hit Louisiana in 2020.

Typhoon Haikui will move through an environment favorable for intensification during the next few hours. Haikui 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 centered north of Taiwan. The ridge will produce easterly winds that will blow toward the top of Haikui’s circulation. The winds in the lower levels of the atmosphere will also blow from the east. So, there will be little vertical wind shear. Typhoon Haikui is likely to continue to intensify during the next few hours until it makes landfall on Taiwan.

Typhoon Haikui will move around the southern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Haikui toward the west- northwest during the next 24 hours. On its anticipated track, the center of Typhoon Haikui will move landfall on the coast of southeast Taiwan near Taitung in nine hours.

Typhoon Haikui will bring strong winds and heavy rain to Taiwan. Haikui will be capable of causing regional serious damage. The heaviest rain will fall on the eastern sides of mountains where the wind will push air up the slopes. Heavy rain is likely to cause flash floods.

Elsewhere over the Western North Pacific Ocean, former Typhoon Saola weakened to a tropical storm along the coast of southern China and former Tropical Storm Kirogi weakened to a tropical depression south of Japan. At 5:00 p.m. EDT on Saturday the center of Tropical Storm Saola was located at latitude 21.6°N and longitude 109.5°E which put it about 35 miles (55 km) east-northeast of Beihai, China. Saola was moving toward the west-southwest at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 991 mb.

At 5:00 p.m. EDT on Saturday the center of Tropical Depression Kirogi was located at latitude 29.6°N and longitude 142.0°E which put it about 370 miles (595 km) south-southeast of Tokyo, Japan. Kirogi was moving toward the northwest at 22 m.p.h. (35 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 1000 mb.

Typhoon Saola Brings Wind and Rain to Hong Kong

Typhoon Saloa brought strong winds and heavy rain to Hong Kong on Friday morning. At 11:00 p.m. EDT on Friday the center of Typhoon Saola was located at latitude 22.1°N and longitude 114.0°E which put it about 20 miles (30 km) southeast of Hong Kong. Saola was moving toward the west at 11 m.p.h. (17 km/h). The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h). The minimum surface pressure was 938 mb.

Powerful Typhoon Saloa brought strong winds and heavy rain to Hong Kong on Friday morning. The Hong Kong International Airport (VHHH) reported a sustained wind speed of 63 m.p.h. (102 km/h) and a wind gust of 85 m.p.h. (139 km/h). The strongest winds in Typhoon Saola were occurring in the South China Sea just to the south of Hong Kong.

Typhoon Saloa started to weaken just as it approached Hong Kong. Northerly winds blowing around the western side of Saola’s circulation pulled drier air over China into the typhoon. The drier air caused Typhoon Saola to start to weaken. Even though Saola started to weaken, it remained a powerful typhoon. Winds to typhoon force extended out 50 miles (80 km) from the center of Typhoon Saola. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation.

The Hurricane Intensity Index (HII) for Typhoon Saola was 25.1. The Hurricane Size Index (HSI) was 16.5 and the Hurricane Wind Intensity Size Index (HWISI) was 41.6. Typhoon Saola was capable of causing region major damage.

Typhoon Saola will move south of a high pressure system over China. The high pressure system will steer Saola toward the west-southwest during the next 24 hours. On its anticipated track, Typhoon Saola will move along the coast of Guangdong province.

Typhoon Saola will continue to produce strong winds and heavy rain in Hong Kong during the next few hours. The strong winds could cause widespread outages of electricity. The heavy rain is likely to cause flash floods in some locations. Typhoon Saloa will weaken as it pulls in more drier air. Even though Saola will weaken, strong winds and heavy rain will spread along the coastal part of Guangdong province west of Hong Kong as Typhoon Saola moves toward the west-southwest during the next 24 hours. Strong winds and heavy rain could reach Macau in a few hours.

Elsewhere over the Western North Pacific Ocean, Typhoon Haikui was moving toward Taiwan and Tropical Storm Kirogi weakened east of Iwo To. At 11:00 a.m. EDT on Friday the center of Typhoon Haikui was located at latitude 22.1°N and longitude 127.3°E which put it about 415 miles (670 km) east of Taiwan. Haikui was moving toward the west at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 971 mb. Typhoon Haikui could approach Taiwan in 36 hours.

At 11:00 a.m. EDT on Friday the center of Tropical Storm Kirogi was located at latitude 23.9°N and longitude 149.0°E which put it about 475 miles (765 km) east of Iwo To. Kirogi was moving toward the northwest at 20 m.p.h. (32 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 999 mb.