Typhoon Koinu Rapidly Intensifies to Equivalent of a Major Hurricane

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.

Tropical Storm Philippe Prompts Watches for Antigua and Barbuda

A potential risk caused by Tropical Storm Philippe prompted the issuance of Tropical Storm Watches for Antigua and Barbuda on Sunday. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Philippe was located at latitude 16.6°N and longitude 59.1°W which put it about 155 miles (245 km) east of Guadeloupe. Philippe 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 998 mb.

Tropical Storm Watches were in effect for Antigua and Barbuda.

Tropical Storm Philippe did not move much on Sunday. The circulation around Philippe also did not change much on Sunday. An upper level ridge over the eastern Caribbean Sea continued to produce northwesterly winds that blew toward the top of Philippe’s circulation. Those winds caused strong vertical wind shear. The vertical wind shear caused the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the southeastern part of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the other parts 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 170 miles (275 km) in the eastern side of Philippe’s circulation. The winds in the western side of Tropical Storm Philippe were blowing at less than tropical storm force.

Tropical Storm Philippe will move through a region that will be unfavorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 29°C. However, the upper level ridge over the eastern Caribbean Sea will continue to cause strong vertical wind shear. The wind shear is likely to prevent intensification of Tropical Storm Philippe on Monday.

Tropical Storm Philippe will move around the southwestern part of a high pressure system over the Atlantic Ocean. The high pressure system will steer Philippe toward the northwest during the next 24 hours. On its anticipated track, Tropical Storm Philippe could move a little closer to Antigua and Barbuda on Monday.

Elsewhere over the Atlantic Ocean, former Tropical Storm Rina weakened to a tropical depression northeast of the Leeward Islands. At 11:00 p.m. EDT on Sunday the center of Tropical Depression Rina was located at latitude 27.1°N and longitude 55.4°W which put it about 785 miles (1265 km) northeast of the Northern Leeward Islands. Rina was moving toward the north at 13 m.p.h. (21 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 1010 mb.

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Koinu Strengthens to a Typhoon

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 Philippe Drifts East of the Leeward Islands

Tropical Storm Philippe drifted over the Atlantic Ocean east of the Leeward Islands on Saturday. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Philippe was located at latitude 16.1°N and longitude 57.0°W which put it about 430 miles (690 km) east-southeast of the Northern Leeward Islands. Philippe was moving toward the southwest 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 999 mb.

Tropical Storm Philippe continued to drift slowly east of the Leeward Islands on Saturday. The circulation around Tropical Storm Philippe did not change much on Saturday. An upper level ridge over the eastern Caribbean Sea produced northwesterly winds that blew toward the top of Philippe’s circulation. Those winds caused strong vertical wind shear. The vertical wind shear caused the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the southeastern part of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the other parts 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 150 miles (240 km) in the eastern side of Philippe’s circulation. Winds to tropical storm force extended out 90 miles (145 km) in the western side of Tropical Storm Philippe.

Tropical Storm Philippe will move through a region that will become marginally favorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 29°C. However, the upper level ridge will continue to cause strong vertical wind shear during the first half of Sunday. The upper level winds could weaken later on Sunday. If the upper level winds weaken, then the strong wind shear will decrease and Tropical Storm Philippe could start to intensify.

Tropical Storm Philippe will move around the southwestern part of a high pressure system over the Atlantic Ocean. The high pressure system will steer Philippe toward the northwest during the next 24 hours. On its anticipated track, Tropical Storm Philippe could move a little closer to the Northern Leeward Islands on Sunday.

Elsewhere over the Atlantic Ocean, Tropical Storm Rina weakened northeast of Tropical Storm Philippe. At 11:00 p.m. EDT on Saturday the center of Tropical Storm Rina was located at latitude 23.5°N and longitude 52.8°W which put it about 760 miles (1220 km) east-northeast of the Northern Leeward Islands. Rina was moving toward the northwest at 14 m.p.h. (22 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 1004 mb.

Tropical Storm Koinu Forms Southeast of Taiwan

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 Philippe Meanders East of the Leeward Islands

Tropical Storm Philippe meandered over the Atlantic Ocean east of the Leeward Islands on Friday. At 11:00 p.m. EDT on Friday the center of Tropical Storm Philippe was located at latitude 17.6°N and longitude 55.8°W which put it about 480 miles (775 km) east of the Northern Leeward Islands. Philippe was moving toward the southwest at 3 m.p.h. (5 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 1002 mb.

Tropical Storm Rina moved around formed the northeastern periphery of Tropical Storm Philippe on Friday. At 11:00 p.m. EDT on Friday the center of Tropical Storm Rina was located at latitude 20.4°N and longitude 48.8°W which put it about 945 miles (1520 km) east-northeast of the Northern Leeward Islands. Rina was moving toward the northwest at 12 m.p.h. (19 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.

The circulations around Tropical Storm Philippe and Tropical Storm Rina continued to interact on Friday. Philippe and Rina revolved around a point between the centers of the two tropical storms in a motion called the Fujiwhara effect. An upper level trough over the Atlantic Ocean east of Bermuda produced westerly winds that were blowing toward the top of Philippe’s circulation. Those winds were causing strong vertical wind shear. The vertical wind shear caused the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the eastern side of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the western 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 140 miles (220 km) in the eastern side of Philippe’s circulation. The winds in the western side of Tropical Storm Philippe were blowing at less than tropical storm force.

The circulation around Tropical Storm Philippe was also affecting Tropical Storm Rina. Upper level divergence from Philippe was adding to the westerly winds blowing toward the top of Rina’ circulation. Those winds caused strong vertical wind shear in Tropical Storm Rina. The wind shear also caused the distribution of thunderstorms in Rina to be asymmetrical. Most of the thunderstorms in Tropical Storm Rina were in bands in the southern and eastern parts of Rina’s circulation. Bands in the northern and western parts of Rina consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 140 miles (220 km) in the eastern part of Rina’s circulation. Winds in the western side of Rina were blowing at less than tropical storm force.

Tropical Storm Philippe will move through a region unfavorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 29°C. However, the upper level trough east of Bermuda will continue to cause strong vertical wind shear. The strong wind shear is likely to keep Tropical Storm Philippe from intensifying on Saturday.

The interaction between Tropical Storm Philippe and Tropical Storm Rina will continue on Saturday. Philippe and Rina will continue their counterclockwise loop around a point in between the two tropical storms. On its anticipated track, Tropical Storm Philippe will move slowly toward the southwest during the next 24 hours. Tropical Storm Rina is forecast to move toward the northwest during the next 24 hours.

Tropical Storm Philippe Stalls East of the Leeward Islands

Tropical Storm Philippe stalled east of the Leeward Islands on Thursday. At 11:00 p.m. EDT on Thursday the center of Tropical Storm Philippe was located at latitude 18.3°N and longitude 55.0°W which put it about 530 miles (855 km) east of the Northern Leeward Islands. Philippe was moving toward the west-southwest at 5 m.p.h. (8 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 1004 mb.

Tropical Storm Rina formed over the Atlantic Ocean about 550 miles (890 km) east of Tropical Storm Philippe on Thursday. At 11:00 p.m. EDT on Thursday the center of Tropical Storm Rina was located at latitude 18.4°N and longitude 46.6°W which put it about 1080 miles (1740 km) east of the Northern Leeward Islands. Rina was moving toward the northwest at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1007 mb.

Tropical Storm Philippe stalled east of the Leeward Islands on Thursday when the circulation around Philippe began to interact with the circulation around Tropical Storm Rina. Philippe also weakened a little on Thursday. An upper level trough over the Caribbean Sea was producing southerly winds that were blowing toward the top of Philippe’s circulation. Those winds were causing strong vertical wind shear. The low level center of Tropical Storm Philippe was large and weak. The wind shear was also causing the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the eastern side of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the western 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 140 miles (220 km) in the eastern side of Philippe’s circulation. The winds in the western side of Tropical Storm Philippe were blowing at less than tropical storm force.

The circulation around Tropical Storm Philippe was also affecting Tropical Storm Rina. Upper level divergence from Philippe was causing vertical wind shear in Tropical Storm Rina. The wind shear was causing the distribution of thunderstorms in Rina to be asymmetrical. Most of the thunderstorms in Tropical Storm Rina were in bands in the southern and eastern parts of Rina’s circulation. Bands in the northern and western parts of Rina consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 70 miles (110 km) in the eastern part of Rina’s circulation. Winds in the western side of Rina were blowing at less than tropical storm force.

Tropical Storm Philippe will move through a region unfavorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 28°C. However, the upper level trough over the Caribbean Sea will continue to cause strong vertical wind shear. The strong wind shear is likely to keep Tropical Storm Philippe from intensifying on Friday.

The interaction between Tropical Storm Philippe and Tropical Storm Rina will increase on Friday. Philippe and Rina are likely to start a counterclockwise loop around a point in between the two tropical storms. The situation when two tropical cyclones loop around a point between them is sometimes called the Fujiwhara effect. On its anticipated track, Tropical Storm Philippe will move slowly toward the west-southwest during the next 24 hours. Tropical Storm Rina is forecast to move slowly toward the northwest during the next 24 hours.

Tropical Storm Philippe Moves Toward Northern Leeward Islands

Tropical Storm Philippe moved toward the Northern Leeward Islands on Wednesday. At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Philippe was located at latitude 18.2°N and longitude 54.5°W which put it about 565 miles (910 km) east of the Northern Leeward Islands. Philippe was moving toward the northwest at 8 m.p.h. (13 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 1002 mb.

Tropical Storm Philippe continued to be affected by strong vertical wind shear on Wednesday. An upper level trough over the eastern Caribbean Sea was producing southwesterly winds that were blowing toward the top of Philippe’s circulation. Those winds were causing strong vertical wind shear. The wind shear was causing the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the eastern side of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the western 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 170 miles (275 km) in the eastern side of Philippe’s circulation. The winds in the western side of Tropical Storm Philippe were blowing at less than tropical storm force.

Tropical Storm Philippe will move through a region unfavorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 28°C. However, the upper level trough over the eastern Caribbean Sea will continue to cause strong vertical wind shear. The strong wind shear is likely to keep Tropical Storm Philippe from intensifying on Thursday.

Tropical Storm Philippe will move around the southern side of a high pressure system over the central Atlantic Ocean. The high pressure system will steer Philippe toward the west-northwest during the next 24 hours. On its anticipated track, Tropical Storm Philippe could approach the Northern Leeward Islands during the weekend.

Tropical Storm Philippe Weakens a Little

Tropical Storm Philippe weakened a little on Tuesday. At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Philippe was located at latitude 17.4°N and longitude 52.0°W which put it about 730 miles (1180 km) east of the Northern Leeward Islands . Philippe was moving toward the west at 12 m.p.h. (19 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 1003 mb.

Tropical Storm Philippe continued to be affected by strong vertical wind shear on Tuesday. An upper level trough over the central Atlantic Ocean was producing southwesterly winds that were blowing toward the top of Philippe’s circulation. Those winds were causing strong vertical wind shear. The wind shear was causing the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the eastern side of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the western 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 230 miles (370 km) in the eastern side of Philippe’s circulation. The winds in the western side of Tropical Storm Philippe were blowing at less than tropical storm force.

Tropical Storm Philippe will move through a region unfavorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 28°C. However, the upper level trough over the central Atlantic will continue to cause strong vertical wind shear. The strong wind shear is likely to cause Tropical Storm Philippe to weaken a little more on Wednesday.

Tropical Storm Philippe will move around the southwestern side of a high pressure system over the eastern Atlantic Ocean. The high pressure system will steer Philippe toward the west during the next 24 hours. On its anticipated track, Tropical Storm Philippe could be northeast of the Northern Leeward Islands by the end of the week.

Tropical Storm Philippe Churns West

Tropical Storm Philippe churned westward over the Atlantic Ocean east of the Leeward Islands on Monday. At 11:00 p.m. EDT on Monday the center of Tropical Storm Philippe was located at latitude 17.6°N and longitude 47.8°W which put it about 1005 miles (1620 km) east of the Northern Leeward Islands. Philippe was moving toward the west-northwest at 12 m.p.h. (19 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 1001 mb.

Tropical Storm Philippe was affected by strong vertical wind shear on Monday. An upper level low over the central Atlantic Ocean was producing westerly winds that were blowing toward the top of Philippe’s circulation. Those winds were causing strong vertical wind shear. The wind shear was causing the distribution of thunderstorms in Tropical Storm Philippe to be asymmetrical. Most of the thunderstorms were occurring in bands in the eastern side of Philippe’s circulation. Bands near the center of Tropical Storm Philippe and in the western 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 170 miles (275 km) in the eastern side of Philippe’s circulation. Tropical storm force winds only extended out 60 miles in the western side of Philippe.

Tropical Storm Philippe will move through a region unfavorable for intensification during the next 24 hours. Philippe will move over water where the Sea Surface Temperatures are near 28°C. However, the upper level low over the central Atlantic will continue to cause strong vertical wind shear. The strong wind shear is likely to cause Tropical Storm Philippe to weaken on Tuesday.

Tropical Storm Philippe will move around the southwestern side of a high pressure system over the eastern Atlantic Ocean. The high pressure system will steer Philippe toward the west-northwest during the next 24 hours. On its anticipated track, Tropical Storm Philippe could be northeast of the Northern Leeward Islands by the end of the week.