Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Surigae Strengthens to Typhoon North of Palau

Former Tropical Storm Surigae strengthened to a typhoon north of Palau on Thursday night. At 11:00 p.m. EDT on Thursday the center of Typhoon Surigae was located at latitude 8.9°N and longitude 134.2°E which put it about 50 miles (80 km) north of Palau. Surigae was moving toward the west-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 973 mb. A weather station at the international airport on Palau reported a sustained wind speed of 46 m.p.h. (74 km/h) and a wind gust of 74 m.p.h. (118 km/h). There were reports of trees down and of wind damage on Palau.

Typhoon Surigae was intensifying more rapidly on Thursday night. Microwave satellite images showed an eye forming at the center of Surigae. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. The strongest rainbands were still in the western half of Typhoon Surigae, but more thunderstorms were developing in bands in the eastern half of the circulation. Storms near the center of Surigae were producing strong upper level divergence that pumped mass away from the typhoon. Winds to typhoon force extended out 30 miles (50 km) from the center of Typhoon Surigae. Winds to tropical storm force extended out 160 miles (260 km) from the center.

Typhoon Surigae will move through an environment favorable for intensification during the next 48 hours. Surigae will be over water where the Sea Surface Temperatures will be near 30°C. It will move under the southwestern part of an upper level ridge over the Western North Pacific Ocean. The ridge will produce easterly winds which will blow toward the top of the circulation. However, the winds at lower levels in the atmosphere will also blow from the east and there will be little vertical wind shear. Typhoon Surigae will continue to intensify and it could strengthen rapidly once an inner core is fully formed. Surigae could intensify to the equivalent of a major hurricane in 24 hours.

Typhoon Surigae will move around the southwestern part of a subtropical high pressure system over the Western North Pacific Ocean during the next few days. The high will steer Surigae toward the west-northwest during the next two days. After that time Typhoon Surigae will move more toward the north when it moves around the western end of the high pressure system. On its anticipated track Typhoon Surigae could be east of the Philippines in 48 hours. Conditions on Palau will improve gradually on Friday when Surigae moves farther away.

Tropical Storm Surigae Strengthens Northeast of Palau

Tropical Storm Surigae strengthened northeast of Palau on Wednesday. At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Surigae was located at latitude 9.1°N and longitude 136.2°E which put it about 120 miles (195 km) west-southwest of Yap. Serigae was moving toward the west-northwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 988 mb.

The circulation around Tropical Storm Surigae strengthened on Wednesday, but the distribution of thunderstorms was still asymmetrical. The strongest thunderstorms were occurring in bands in the western half of Surigae. Bands in the eastern half of the circulation consisted primarily of showers and lower clouds. Thunderstorms west of the center of circulation generated upper level divergence that pumped mass away to the west of the tropical storm. Winds to tropical storm force extended out 140 miles (220 km) from the center of Tropical Cyclone Surigae.

Tropical Storm Surigae will move through an environment favorable for intensification during the next several days. Surigae will be over water where the Sea Surface Temperatures will be near 30°C. It will move under the southwestern part of an upper level ridge over the Western North Pacific Ocean. The ridge will produce easterly winds which will blow toward the top of the circulation. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. Tropical Storm Surigae will continue to intensify and it could strengthen to a typhoon within 24 hours.

Tropical Storm Surigae will move around the southwestern part of a subtropical high pressure system over the Western North Pacific Ocean during the next few days. The high will steer Surigae toward the west-northwest during the next few days. On its anticipated track Tropical Storm Surigae will pass north of Palau during the next 36 hours. Surigae could be east of the Philippines by late this week.

Tropical Storm Surigae Develops Southwest of Yap

Tropical Storm Surigae developed southwest of Yap on Tuesday. At 5:00 p.m. EDT on Tuesday the center of Tropical Storm Surigae was located at latitude 8.2°N and longitude 137.1°E which put it about 35 miles (55 km) west-southwest of Ngulu. Serigae was moving toward the northwest at 4 m.p.h. (6 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.

Former Tropical Depression 02W strengthened southwest of Yap on Tuesday and the Japan Meteorological Agency designated the system as Tropical Storm Surigae. The circulation around Tropical Storm Surigae exhibited more organization on satellite images. Thunderstorms developed near the center of circulation. More thunderstorms also formed in bands revolving around the center of Surigae. Storms near the center of circulation began to generate upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 50 miles (80 km) from the center.

Tropical Storm Surigae will be in an environment favorable for intensification during the next several days. Surigae will be over water where the Sea Surface Temperatures will be near 30°C. It will be under the 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. The circulation around Tropical Storm Surigae will continue to get better organized. Surigae will intensify and it could strengthen to a typhoon within 48 hours.

Tropical Storm Surigae will move around the southwestern part of a subtropical high pressure system over the Western North Pacific Ocean during the next few days. The high will steer Surigae toward the northwest during the next few days. On its anticipated track Tropical Storm Surigae will pass north of Palau. Bands on the eastern side of Tropical Storm Surigae could bring gusty winds and locally heavy rain to Yap. Persistent heavy rain could cause flash floods. Surigae could be east of the Philippines by late this week.

Tropical Depression Forms Southeast of Yap

A tropical depression formed southeast of Yap on Monday night. At 8:00 p.m. EDT on Monday the center of the tropical depression was located at latitude 7.1°N and longitude 139.9°E which put it about 200 miles (320 km) southeast of Yap. The tropical depression was nearly stationary. 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 1006 mb.

An area of low pressure exhibited more organization on Monday night and the Japan Meteorological Agency designated the system as a tropical depression. The circulation around the tropical depression was in the early stages of organization. There was a broad center of low pressure, but there were not a lot of thunderstorms near the center of circulation. Many of the stronger thunderstorms were occurring in two bands on the periphery of the tropical depression. The strongest rainband was north of the broad center of the depression. Another strong rainband was on the southern periphery of the circulation.

The tropical depression will be in an environment favorable for intensification during the next several days. The depression will be over water where the Sea Surface Temperatures will be near 30°C. It will be under the center of an upper level ridge over the Western North Pacific Ocean. The upper level winds are weak in the center of the ridge and there will be little vertical wind shear. The circulation around the tropical depression is forecast to gradually get better organized and it could strengthen to a tropical storm during the next 24 hours. The depression is forecast to intensify into a typhoon later this week.

The tropical depression will be in an area where the steering winds are weak during the next several days. It will remain nearly stationary during that time period. A subtropical high pressure system over the Western North Pacific Ocean will begin to steer the tropical depression toward the northwest later this week. On its anticipated track the tropical depression will pass near Yap. It will bring gusty winds and locally heavy rain. Persistent heavy rain could cause flash floods.

Dujuan Weakens to a Tropical Depression

Former Tropical Storm Dujuan weakened to a tropical depression on Saturday. At 10:00 a.m. EST on Saturday the center of Tropical Depression Dujuan was located at latitude 8.4°N and longitude 129.6°E which put it about 210 miles (335 km) east of Hinatuan, Philippines. Dujuan was moving toward the west-northwest at 5 m.p.h. (8 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 1003 mb.

Strong easterly winds in the upper troposphere blew the top off of former Tropical Storm Dujuan on Friday night. The circulation in the lower levels gradually weakened and Dujuan was classified as a tropical depression on Saturday. The low level circulation consisted almost entirely of showers and lower clouds during much of Saturday. A few thunderstorms developed northeast of the center of Tropical Depression Dujuan on Saturday night, but it was not clear that the thunderstorms would persist.

Tropical Depression Dujuan will move through an environment unfavorable for intensification during the next 48 hours. Dujuan will move over water where the Sea Surface Temperature is near 28°C. So, there will be enough energy in the upper ocean to support intensification. However, Tropical Depression Dujuan will move under the southern part of an upper level ridge over the Western North Pacific Ocean. The ridge will continue to produce strong easterly winds which will blow toward the top of Dujuan. In addition, a surface high pressure system over eastern Asia will produce strong northeasterly winds in the lower levels. Those winds will transport drier air over the Philippines. The combination of vertical wind shear and drier air will likely prevent intensification of Tropical Depression Dujuan.

Tropical Depression Dujuan will move south of a high pressure system over the Western North Pacific Ocean. The high will steer Dujuan toward the west-northwest during the next several days. On its anticipated track Tropical Depression Dujuan could approach northern Mindano, southern Samar and Cebu in 18 hours. Dujuan will bring gusty winds and locally heavy rain to parts of the central Philippines.

Tropical Storm Dujuan Moves Toward Mindanao

Tropical Storm Dujuan moved toward Mindanao on Friday. At 10:00 a.m. EST on Friday the center of Tropical Storm Dujuan was located at latitude 6.2°N and longitude 130.1°E which put it about 320 miles (515 km) east of Davao, Philippines. Dujuan was moving toward the west at 9 m.p.h. (11 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.

The distribution of thunderstorms around Tropical Storm Dujuan was asymmetrical. The strongest thunderstorms were occurring in bands in the northwestern quadrant of Dujuan. Bands in the rest of the tropical storm consisted primarily of showers and lower clouds. Storms northwest of the center of circulation generated upper level divergence which pumped mass away to the northwest of the tropical storm. Winds to tropical storm force extended out 200 miles (320 km) from the center of Dujuan.

Tropical Storm Dujuan will move through an environment unfavorable for intensification during the next 48 hours. Dujuan will move over water where the Sea Surface Temperature is near 29°C. So, there will be enough energy in the upper ocean to support intensification. However, Tropical Storm Dujuan will move under the southern part of an upper level ridge over the Western North Pacific Ocean. The ridge will produce strong easterly winds which will blow toward the top of Dujuan. Those winds are causing the asymmetrical distribution of thunderstorms and they will create strong vertical wind shear. In addition, a surface high pressure system over eastern Asia will produce strong northeasterly winds in the lower levels. Those winds will transport drier air over the Philippines. The combination of vertical wind shear and drier air will likely prevent further intensification of Tropical Storm Dujuan. Dujuan is likely to weaken gradually during the next 36 hours.

Tropical Storm Dujuan will move south of a high pressure system over the Western North Pacific Ocean. The high will steer Dujuan toward the west-northwest during the next several days. On its anticipated track Tropical Storm Dujuan could approach northeastern Mindano in 36 hours. Dujuan could be a tropical storm when it reaches Mindanao. It will bring gusty winds and locally heavy rain to Mindano and other parts of the southern Philippines.

Tropical Storm Dujuan Develops East of Mindanao

Tropical Storm Dujuan developed east of Mindanao on Thursday. At 10:00 a.m. EST on Thursday the center of Tropical Cyclone Dujuan was located at latitude 7.3°N and longitude 131.6°E which put it about 430 miles (695 km) east of Davao, Philippines. Dujuan was moving toward the west-northwest at 4 m.p.h. (6 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.

The circulation around an area of low pressure east of the Philippines strengthened on Thursday morning and the Japan Meteorological Agency designated the system as Tropical Storm Dujuan. The distribution of thunderstorms around Tropical Storm Dujuan was asymmetrical. The strongest thunderstorms were occurring in bands in the western half of Dujuan. Bands in the eastern half of the tropical storm consisted primarily of showers and lower clouds. Storms west of the center of circulation began to generate upper level divergence which pumped mass away to the west of the tropical storm. Winds to tropical storm force extended out 100 miles (160 km) from the center of Dujuan.

Tropical Storm Dujuan will move through an environment somewhat favorable for intensification during the next 36 hours. Dujuan will move over water where the Sea Surface Temperature is near 29°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 which will blow toward the top of Tropical Storm Dujuan. Those winds will create moderate vertical wind shear and they are causing the asymmetrical distribution of thunderstorms. The wind shear will inhibit intensification, but it will not be strong enough to prevent Dujuan from strengthening. Tropical Storm Dujuan is likely to intensify gradually during the next 36 hours.

Tropical Storm Dujuan will move south of a high pressure system over the Western North Pacific Ocean. The high will steer Dujuan toward the west-northwest during the next several days. On its anticipated track Tropical Storm Dujuan could approach northeastern Mindano in 48 hours. Dujuan could bring gusty winds and locally heavy rain to Mindano and other parts of the southern Philippines.

Tropical Storm Krovanh Develops over South China Sea

Tropical Storm Krovanh developed over the South China Sea on Sunday. At 4:00 p.m. EST on Sunday the center of Tropical Storm Krovanh was located at latitude 9.7°N and longitude 113.9°E which put it about 515 miles (830 km) east of Ho Chi Minh City, Vietnam. Krovanh was moving toward the west-southwest 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 50 m.p.h. (80 km/h). The minimum surface pressure was 1001 mb.

The circulation around Tropical Storm Krovanh was very asymmetrical. A high pressure system over eastern Asia was contributing to a strong pressure gradient northwest of Krovanh. The pressure gradient between the high pressure system and Krovanh was producing strong northeasterly winds in the northwestern quadrant of the tropical storm. Winds to tropical storm force extended out 300 miles (485 km) in the northwestern quadrant of Tropical Storm Krovanh. However, winds in the southeastern quadrant of Krovanh were blowing at less than tropical storm force.

Tropical Storm Krovanh will move through an environment that is only marginally favorable for intensification. Krovanh will move over water where the Sea Surface Temperature is near 27°C. So, there will be enough energy in the upper ocean to support intensification. However, the northeasterly winds on the northwestern side of Tropical Storm Krovanh will transport drier air into the circulation. The drier air will inhibit the development of thunderstorms. Krovanh will move under the southern part of an upper level ridge over the Western North Pacific Ocean. The ridge will produce strong easterly winds which will blow toward the top of the tropical storm. Those winds will cause moderate vertical wind shear, which will also inhibit intensification. Tropical Storm Krovanh could intensify a little during the next 24 hours, but the dry air and wind shear are likely to cause it to weaken next week.

Tropical Storm Krovanh will move around the southern side of the high pressure system over eastern Asia. The high will steer Krovanh toward the west-southwest during the next several days. On its anticipated track Tropical Storm Krovanh could be near the southernmost part of Vietnam in about three days.

Typhoon Vamco Brings Wind and Rain to Vietnam

Typhoon Vamco brought wind and rain to Vietnam on Saturday night. At 10:00 p.m. EST on Saturday the center of Typhoon Vamco was located at latitude 17.3°N and longitude 107.5°E which put it about 40 miles (65 km) east of Vinh Linh, Vietnam. Vamco was moving toward the northwest at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h). The minimum surface pressure was 979 mb.

The center of Typhoon Vamco was about to make landfall on the coast of Vietnam between Vinh Linh and Dong Hoi on Saturday night. Bands on the western side of Vamco were already bringing wind and rain to Vietnam. A flow of drier air from eastern Asia into the western part of the circulation around Vamco caused the typhoon to weaken as it approached Vietnam. Even though it was weaker, Typhoon Vamco was still capable of causing serious damage. Winds to typhoon force extended out 30 miles (50 km) from the center of Vamco. Winds to tropical storm force extended out 130 miles (210 km from the center.

Typhoon Vamco will bring strong winds to the coast of central Vietnam during the next few hours. Wind blowing water toward the coast will cause a storm surge north of Vinh Linh. The winds blwoing around Vamco will weaken when it moves inland. However, Typhoon Vamco will drop heavy rain over parts of central Vietnam, southern Laos and northeastern Thailand. Heavy rain will fall on saturated ground and significant flooding is likely to occur.

Typhoon Vamco Strengthens to Equivalent of Major Hurricane

Typhoon Vamco strengthened to the equivalent of a major hurricane east of Vietnam on Friday. At 4:00 p.m. EST on Friday the center of Typhoon Vamco was located at latitude 15.7°N and longitude 111.9°E which put it about 275 miles (440 km) east of Da Nang, Vietnam. Vamco was moving toward the west at 12 m.p.h. (19 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 954 mb.

Typhoon Vamco rapidly intensified into the equivalent of a major hurricane over the East China east of Vietnam on Friday. The circulation contracted around a small clear eye. 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 of Typhoon Vamco. Storms near the core were generating strong upper level divergence which was pumping mass away fro the typhoon. The removal of mass allowed the pressure to decrease rapidly which contributed to the rabid intensification.

Winds to typhoon force extended out 40 miles (65 km) from the center of Typhoon Vamco. Winds to tropical storm force extended out 200 miles (320 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Vamco was 25.1. The Hurricane Size Index (HSI) was 16.7 and the Hurricane Wind Intensity Size Index (HWISI) was 41.8. Vamco was capable of causing significant damage.

Typhoon Vamco will move through an environment that will become less favorable for intensification during the next day or so. Vamco will move over water where the Sea Surface Temperature is near 28°C. So, there will be enough energy in the upper ocean to support an intense typhoon. However, northeasterly winds will transport drier air over eastern Asia toward the western side of Typhoon Vamco. Vamco is likely to start to weaken when the drier air is pulled into the core of the circulation.

Typhoon Vamco will move south of a high pressure system over the eastern Asia. The high will steer Vamco toward the west during the next several days. On its anticipated track Typhoon Vamco will approach the coast of Vietnam north of Da Nang in about 24 hours. Vamco is likely to still be a typhoon when it reaches Vietnam. Typhoon Vamco will drop heavy rain over Vietnam, Laos and northeastern Thailand. The rain will fall on saturated surfaces and floods will occur in those areas.