Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Tropical Storm Mulan Forms South of Hong Kong

Tropical Storm Mulan formed over the South China Sea south of Hing Kong on Tuesday morning. At 5:00 a.m. EDT on Tuesday the center of Tropical Storm Mulan was located at latitude 17.9°N and longitude 112.8°E which put it about 280 miles (450 km) south of Hong Kong. Mulan was moving toward the north at 13 m.p.h. (20 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.

A small low pressure system on the eastern side of a much larger low pressure system over the South China Sea south of Hong Kong strengthened on Tuesday morning and the Japan Meteorological Agency designated the system as Tropical Storm Mulan. The circulation around Tropical Storm Mulan was embedded in a larger low pressure system over the South China Sea which had a diameter of 700 miles (1130 km). The distribution of thunderstorms around Mulan was asymmetrical. Thunderstorms were occurring mainly in bands in the eastern half of Mulan’s circulation. Bands in the western half of the circulation consisted primarily of showers and lower clouds. Storms near the center of Mulan’s circulation generated upper level divergence that pumped mass away from the tropical storm.

Tropical Storm Mulan will move through an environment marginally favorable for intensification during the next 24 hours. Mulan will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the eastern side of a broad upper level low over the South China Sea. The upper low will produce southerly winds that will blow toward the top of Mulan’s circulation. The winds at lower levels in the atmosphere will also blow from the south. So, there will be little vertical wind shear. Even though the water will be warm and there will be little vertical wind shear, the fact that Tropical Storm Mulan is a smaller low pressure system embedded in a much larger low pressure system is likely to inhibit intensification.

Tropical Storm Mulan will move around the northeastern part of the larger low pressure system over the South China Sea during the next 24 hours. The larger low pressure system will steer Mulan toward the northwest. On its anticipated track Tropical Storm Mulan could approach the south coast of China near Zhanjiang within 24 hours. Mulan will bring gusty winds and locally heavy rain to parts of southern China. Heavy rain could cause flash floods in some locations.

Tropical Storm Trases Develops over the East China Sea

Tropical Storm Trases developed over the East China Sea south of Jeju Island, South Korea on Sunday afternoon. At 2:00 p.m. EDT on Sunday the center of Tropical Storm Trases was located at latitude 30.1°N and longitude 126.3°E which put it about 175 miles (280 km) south of Jeju Island, South Korea. Trases was moving toward the north-northwest at 18 m.p.h. (29 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 998 mb.

The circulation at the center of a large low pressure system over the East China Sea strengthened on Sunday afternoon and the Japan Meteorological Agency designated the system as Tropical Storm Trases. The distribution of thunderstorms around Tropical Storm Trases was asymmetrical. Thunderstorms were occurring in bands in the southern part of Trases’ circulation. Bands in the other part of the tropical storm consisted primarily of showers and lower clouds. The air in the northern part of Tropical Storm Trases was cooler and drier. The cooler, drier air was inhibiting the formation of thunderstorms in that part of Trases.

Tropical Storm Trases will move through an environment marginally favorable for intensification during the next 12 hours. Trases will will move over water where the Sea Surface Temperatures are near 26˚C. It will move under the axis of an upper level ridge centered north of Japan. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. However, the cooler drier air on the northern side of Trases will limit the potential for intensification. Tropical Storm Trases could intensify a little during the next 12 hours. Trases will move over cooler water on Monday and it is likely to weaken at that time.

Tropical storm Trases will move around the western side of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Trases toward the north during the next 24 hours. On its anticipated track the center of Tropical Storm Trases could reach Jeju Island within 12 hours. Trases could make landfall on the west coast of South Korea on Monday. Tropical Storm Trases will bring gusty winds and locally heavy rain to parts of South Korea.

Tropical Storm Songda Develops East of Okinawa

Tropical Storm Songda developed east of Okinawa on Thursday afternoon. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Songda was located at latitude 26.4°N and longitude 136.6°E which put it about 600 miles (970 km) east of Okinawa. Songda was moving toward the north-northwest at 29 m.p.h. (45 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1002 mb.

An area of low pressure strengthened east of Okinawa on Thursday afternoon and the Japan Meteorological Agency designated the system as Tropical Storm Songda. Tropical Storm Songda was revolving around the northeastern part of a much larger low pressure system (sometimes called a monsoon gyre) centered northeast of the Philippines. The interaction of Songda’s circulation with the larger low pressure system was producing an asymmetrical distribution of thunderstorms. Thunderstorms were occurring in bands in the northeastern half of Tropical Storm Songda. Bands in the southwestern half of Songda consisted primarily of showers and lower clouds. Storms near the center of Songda generated upper level divergence that pumped mass away to the northeast of the tropical storm.

Tropical Storm Songda will move through an environment marginally favorable for intensification during the next 24 hours. Songda will move over water where the Sea Surface Temperatures are near 30˚C. The circulation around the larger low pressure system will produce upper level winds from the southeast that will blow toward the top of Songda’s circulation. The winds in the lower levels of the atmosphere will also be blowing from the southeast and so there will be less vertical wind shear. The wind shear could still be strong enough to inhibit intensification. Songda could also move into a region where the air is drier. Tropical Storm Songda could strengthen a little during the next 24 hours, but wind shear and drier air are likely to limit intensification.

The large low pressure system northeast of the Philippines will steer Tropical Storm Songda toward the northwest during the next 24 hours. On its anticipated track Tropical Storm Sondga could approach the northern Ryukyu Islands within 24 hours. Songda could bring gusty winds and locally heavy rain to the northern Ryukyu Islands.

Typhoon Chaba Hits Southern China

Typhoon Chaba hit southern China on Saturday morning. At 5:00 a.m. EDT on Saturday the center of Typhoon Chaba was located at latitude 21.5°N and longitude 111.0°E which put it about 25 miles (40 km) east of Wuchuan, China. Chaba was moving toward the north-northwest at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 80 m.p.h. (130 km/h) and and there were wind gusts to 95 m.p.h. (150 km/h). The minimum surface pressure was 978 mb.

The center of Typhoon Chaba made landfall on the south coast of China near Wuchuan and Dianbai in Guangdong on Saturday morning. Typhoon Chaba was strengthening when it made landfall. A small circular eye was as the center of Chaba’s circulation. Winds to typhoon force extended out 60 miles (95 km) from the center of Chaba. Winds to tropical storm force extended out 190 miles (305 km) from the center of circulation.

Typhoon Chaba will move around the western end of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Chaba toward the north-northwest during the next 24 hours. On its anticipated track Typhoon Chaba will move inland over southern China. Chaba will weaken gradually as it moves inland. Typhoon Chaba will bring strong winds and locally heavy rain to southwestern Guangdong. Heavy rain could cause flash floods in some locations. There were reports a ship broke in two in heavy seas in the South China Sea.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Aere brought gusty winds and heavy rain to the center Ryukyu Islands. At 5:00 p.m. EDT on Saturday the center of Tropical Storm Aere was located at latitude 26.3°N and longitude 129.1°E which put it about 115 miles (185 km) east-southeast of Okinawa. Aere was moving toward the north-northwest at 17 m.p.h. (19 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 994 mb.

Chaba Strengthens to a Typhoon Northeast of Hainan

Former Tropical Storm Chaba strengthened to a typhoon northeast of Hainan Island on Friday afternoon. At 5:00 p.m. EDT on Friday the center of Typhoon Chaba was located at latitude 20.4°N and longitude 111.8°E which put it about 100 miles (160 km) southeast of Wuchuan, China. Chaba was moving toward the northwest at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 981 mb.

Former Tropical Storm Chaba strengthened to a typhoon over the warm water in the northern South China Sea on Friday afternoon. The inner end of a rainband wrapped around the center of Typhoon Chaba’s circulation and the strongest winds were occurring in a ring around the center. Bands of showers and thunderstorms were revolving around the core of Typhoon Chaba. Storms near the core generated upper level divergence that pumped mass away from the typhoon. Winds to typhoon force extended out 60 miles (95 km) from the center of Chaba. Winds to tropical storm force extended out 180 miles (290 km) from the center of circulation.

Typhoon Chaba will move through an environment favorable for intensification during the next 12 hours. Chaba will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the middle of an upper level ridge over the northern part of the South China Sea. The upper level winds are weak near the center of the ridge and there will be little vertical wind shear. Typhoon Chaba could continue to intensify during the next 12 hours.

Typhoon Chaba will move around the western end of a high pressure system over the Western North Pacific Ocean during the next 24 hours. The high will steer Chaba toward the northwest. On its anticipated track the center of Typhoon Chaba could make landfall on the coast of southern China near Wuchuan in 12 hours. Chaba will bring strong winds and locally heavy rain to southwestern Guangdong. Heavy rain is likely to cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Aere intensified gradually southeast of Okinawa. At 5:00 p.m. EDT on Friday the center of Tropical Storm Aere was located at latitude 23.6°N and longitude 130.4°E which put it about 305 miles (495 km) southeast of Okinawa. Aere was moving toward the north-northwest at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 994 mb. Tropical Storm Aere is forecast to move toward the north-northwest and to continue to strengthen gradually. Aere could be near Okinawa in 18 hours.

Tropical Storm Chaba Strengthens South of Hong Kong

Tropical Storm Chaba strengthened over the South China Sea south of Hong Kong on Thursday night. At 11:00 p.m. EDT on Thursday the center of Tropical Storm Chaba was located at latitude 18.6°N and longitude 113.7°E which put it about 275 miles (445 km) south of Hong Kong, China. Chaba was moving toward the northwest at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 991 mb.

Tropical Storm Chaba strengthened south of Hong Kong on Thursday night. The inner end of a rainband wrapped around most of the center of circulation. The strongest winds were occurring in the part of the rainband wrapped around the center. Bands of thunderstorms were occurring in the southern half of Chaba’s circulation. Bands in the northern half of Chaba contained more showers and lower clouds. Storms near the center of circulation pumped mass away to the south and west of the tropical storm. Winds to tropical storm force extended out 140 miles (225 km) from the center.

Tropical Storm Chaba will move through an environment favorable for intensification during the 24 hours. Chaba will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the middle of an upper level ridge over the northern part of the South China Sea. The upper level winds are weak near the center of the ridge and there will be little vertical wind shear. Tropical Storm Chaba will continue to intensify during the next 24 hours and it could strengthen to a typhoon.

Tropical Storm Chaba will move around the western end of a high pressure system over the Western North Pacific Ocean during the next 24 hours. The high will steer Chaba toward the northwest. On its anticipated track the center of Tropical Storm Chaba could be near the northeastern part of Hainan Island in 18 hours. Chaba could approach the coast of southern China near Zhanjiang in 24 hours. Chaba could be a typhoon when it approaches southern China. It will bring strong winds and locally heavy rain. Heavy rain is likely to cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Aere formed south-southeast of Okinawa. At 11:00 p.m. EDT on Thursday the center of Tropical Storm Aere was located at latitude 20.8°N and longitude 130.8°E which put it about 470 miles (760 km) south-southeast of Okinawa. Aere was moving toward the east-northeast at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1000 mb. Tropical Storm Aere is forecast to move toward the north-northwest and to strengthen gradually. Aere could be near Okinawa in 36 hours.

Tropical Storm Chaba Forms over South China Sea

Tropical Storm Chaba formed over the South China Sea south of Hong Kong on Wednesday night. At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Chaba was located at latitude 15.7°N and longitude 115.1°E which put it about 440 miles (710 km) south of Hong Kong, China. Chaba was moving toward the northeast at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1000 mb.

The circulation around a low pressure system over the South China Sea south of Hong Kong strengthened on Wednesday night and the Japan Meteorological Agency designated the system as Tropical Storm Chaba. The distribution of thunderstorms around Tropical Storm Chaba was asymmetrical. The strongest thunderstorms were occurring in bands in the western half of Chaba’s circulation. Bands in the eastern half of the circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 115 miles (185 km) from the center of circulation.

An upper level ridge over southern China was producing northeasterly winds that were blowing toward the top of Tropical Storm Chaba. Those winds were causing moderate vertical wind shear. The wind shear was contributing to the asymmetrical distribution of thunderstorms.

Tropical Storm Chaba will move through an environment somewhat favorable for intensification during the 36 hours. Chaba will move over water where the Sea Surface Temperatures are near 29˚C. However, the upper level ridge over southern China will continue to cause vertical wind shear. The wind shear will inhibit intensification, but the shear will not be strong enough to prevent some intensification of Chaba. Tropical Storm Chaba is likely to intensify gradually during the next 36 hours.

Tropical Storm Chaba will move around the western end of a high pressure system over the Western North Pacific Ocean during the next 36 hours. The high will steer Chaba toward the north-northwest. On its anticipated track Tropical Storm Chaba could approach Hainan Island and the coast of southern China in 36 hours.

Typhoon Malakas Brings Winds and Rain to Iwo To

Typhoon Malakas brought strong winds and heavy rain to Iwo To on Thursday. At 5:00 p.m. EDT on Thursday the center of Typhoon Malakas was located at latitude 25.6°N and longitude 140.4°E which put it about 100 miles (160 km) west of Two To. Malakas was moving toward the north-northeast at 24 m.p.h (39 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 964 mb.

Typhoon Malakas weakened as it approached Iwo To, but Malakas still brought strong winds and heavy rain to the island. An upper level trough near Japan was producing strong southwesterly winds that were blowing toward the top of Malakas’ circulation. Those winds were causing strong vertical wind shear and the shear was affecting the distribution of thunderstorms. The strongest thunderstorms were occurring in bands in the eastern half of Typhoon Malakas. Bands in the western half of the circulation consisted primarily of showers and lower clouds.

There continued to be a large circulation around Typhoon Malakas. Winds to typhoon force extended out 60 miles (95 km) from the center of Malakas. Winds to tropical storm force extended out 200 miles (320 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Malakas was 17.8. The Hurricane Size Index (HSI) was 21.1 and the Hurricane Wind Intensity Size Index (HWISI) was 38.9.

Typhoon Malakas will move through an environment unfavorable for intensification during the next 36 hours. Malakas will move over water where the Sea Surface Temperatures are near 23˚C. The upper level trough near Japan will continue to produce strong southwesterly winds that will blow toward the top of the typhoon’s circulation. Those winds will cause strong vertical wind shear. Typhoon Malakas will continue to weaken during the next 36 hours. The combination of colder water and strong vertical wind shear will cause Malakas to make a transition to a strong extratropical cyclone.

The upper level trough near Japan will steer Typhoon Malakas quickly toward the northeast during the next 36 hours. On its anticipated track Typhoon Malakas will cross the Ogasawara Islands during the next 24 hours. Malakas will bring strong winds and heavy rain the Ogasawara Islands. Heavy rain could cause flash floods in some locations. Weather conditions should improve on Iwo To on Friday when Malakas moves away from the island.

Typhoon Malakas Intensifies to Equivalent of Cat. 4 Hurricane

Typhoon Malakas intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Wednesday morning. At 11:00 a.m. EDT on Wednesday the center of Typhoon Malakas was located at latitude 19.3°N and longitude 137.5°E which put it about 475 miles (770 km) south-southwest of Two To. Malakas was moving toward the north-northeast at 13 m.p.h (20 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 939 mb.

Typhoon Malakas strengthened to the equivalent of a Cat. 4 hurricane on the Saffir-Simpson Scale over the Western North Pacific Ocean south-southwest of Iwo To on Wednesday morning. A circular eye with a diameter of 30 miles (50 km) was at the center of Malakas’ circulation. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core to Typhoon Malakas. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Malakas was large. Winds to typhoon force extended out 65 miles (105 km) from the center of Malakas. Winds to tropical storm force extended out 260 miles (415 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Malakas was 25.1. The Hurricane Size Index (HSI) was 24.0 and the Hurricane Wind Intensity Size Index (HWISI) was 49.1.

Typhoon Malakas will move into an environment unfavorable for intensification during the next 12 hours. Malakas will move over water where the Sea Surface Temperatures are near 26˚C. An upper level trough west of Japan will move toward Malakas. When the upper level trough gets closer to Typhoon Malakas, it will produce southwesterly winds that will blow toward the top of the typhoon’s circulation. Those winds will cause the vertical wind shear to increase. When the shear increases, Typhoon Malakas will start to weaken.

The upper level trough west of Japan will steer Typhoon Malakas toward the north-northeast during the next 24 hours. On its anticipated track Malakas could approach Iwo To in 30 hours. Typhoon Malakas will bring strong winds and heavy rain to Iwo To and the Ogasawara Islands. Heavy rain could cause flash floods in some locations.

Typhoon Malakas Strengthens to Equivalent of a Major Hurricane

Typhoon Malakas strengthened to the equivalent of a major hurricane southwest of Iwo To on Tuesday night. At 11:00 p.m. EDT on Tuesday the center of Typhoon Malakas was located at latitude 17.7°N and longitude 136.6°E which put it about 605 miles (980 km) southwest of Two To. Malakas was moving toward the northeast 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 Malakas strengthened quickly to the equivalent of a major hurricane over the Western North Pacific Ocean southwest of Iwo To on Tuesday night. A circular eye with a diameter of 25 miles (40 km) was at the center of Malakas’ circulation. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core to Typhoon Malakas. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The size of the circulation around Typhoon Malakas increased on Tuesday. Winds to typhoon force extended out 75 miles (120 km) from the center of Malakas. Winds to tropical storm force extended out 240 miles (390 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Malakas was 22.1. The Hurricane Size Index (HSI) was 25.6 and the Hurricane Wind Intensity Size Index (HWISI) was 47.7.

Typhoon Malakas will move through an environment favorable for intensification during the next 12 hours. Malakas will move over water where the Sea Surface Temperatures are near 27˚C. It will move under the western part of an upper level ridge over the Western North Pacific Ocean. The ridge will produce southerly winds that will blow toward the top of Malakas’ circulation. The winds at lower levels in the atmosphere will also blow from the south and there will not be much vertical wind shear. Typhoon Malakas could continue to intensify during the next 12 hours. An upper level trough west of Japan will move toward Malakas on Wednesday. When the upper level trough gets closer to Malakas, it will produce southwesterly winds that will blow toward the top of the typhoon’s circulation. Those winds will cause the vertical wind shear to increase. When the shear increases later on Wednesday Typhoon Malakas could start to weaken.

The upper level trough west of Japan will start to steer Typhoon Malakas toward the northeast at a faster speed later on Wednesday. On its anticipated track Malakas could approach Iwo To in 36 hours. Typhoon Malakas will bring strong winds and locally heavy rain to Iwo To and the Ogasawara Islands.