Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Tropical Depression 35W Drops Heavy Rain on the Philippines

Tropical Depression 35W dropped heavy rain on parts of the Philippines on Friday.  At 10:00 a.m. EST on Friday the center of Tropical Depression 35W was located at latitude 10.7°N and longitude 127.3°E which put it about 135 miles (215 km) east of Tacloban, Philippines.  It was moving toward the west at 7 m.p.h. (11 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 1001 mb.

The distribution of rain around Tropical Depression 35W was asymmetrical.  Most of the heavy rain was falling in thunderstorms northwest of the center of circulation.  A few thunderstorms were developing northeast of the center, but most of the bands in the rest of the tropical depression consisted of showers and lower clouds.  Tropical Depression 35W was located southwest of a strong subtropical ridge over the Western North Pacific Ocean.  The ridge was producing strong upper level winds which were blowing from the east-southeast.  Those winds were blowing across the top of the tropical depression and they were causing strong vertical wind shear.  The strong wind shear was the reason why most of the heavy rain was falling northwest of the center of circulation.

Tropical Depression 35W will move through an environment marginally favorable for intensification.  It will move over water where the Sea Surface Temperature is near 29°C.  The subtropical ridge will continue to cause vertical wind shear.  However, the tropical depression could move under slightly weaker upper level winds when it moves a little farther to the west.  If it moves under weaker upper level winds, then Tropical Depression 35W could strengthen into a tropical storm.

The subtropical ridge will steer Tropical Depression 35W westward for another 24 to 36 hours.  When the depression moves west of the Philippines, it will encounter strong northeasterly winds blowing around a high pressure system over Asia.  Those winds will steer Tropical Depression 35W toward the southwest when it moves over the South China Sea.

Tropical Depression 35W will drop heavy rain over parts of the Philippines.  The heaviest rain is likely to fall over Samar, Cebu, Bohoi, Panay, Mindoro and the southeastern part of Luzon.  The heavy rain will cause flash floods, and mudslides could occur in regions of steeper terrain.

Tropical Storm Usagi Makes Landfall South of Ho Chi Minh City

Tropical Storm Usagi made landfall south of Ho Chi Minh City, Vietnam on Saturday night.  At 10:00 p.m. EST on Saturday the center of Tropical Storm Usagi was located at latitude 10.2°N and longitude 107.1°E which put it about 60 miles (995 km) south-southeast of Ho Chi Minh City, Vietnam.  Usagi was moving toward the west at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 984 mb.

Former Typhoon Usagi weakened as it approached the coast of southern Vietnam.  Moderate vertical wind shear caused by upper level winds blowing from the east caused Usagi to weaken slowly.  The core of Tropical Storm Usagi was still relatively intact.  A ring of strong thunderstorms surrounded the remnants of the small eye.  The strongest winds were occurring in that ring of storms.  Heavy rain was falling just to the southwest of the center of circulation.  Thunderstorms were also dropping heavy rain in a couple of bands on the northeastern periphery of the circulation.

Tropical Storm Usagi will bring gusty winds to the areas south and west of Ho Chi Minh City.  Some places in southern Vietnam and Cambodia will receive locally heavy rainfall and flash floods could occur in those areas.  Usagi will weaken slowly as it move inland over southern Vietnam.

Elsewhere over the Western North Pacific Ocean, Typhoon Man-yi was meandering slowly southeast of Okinawa.  At 10:00 p.m. EST on Saturday the center of Typhoon Man-yi was located at latitude 18.4°N and longitude 135.8°E which put it about 770 miles (1245 km) southeast of Okinawa.  Man-yi was moving toward the west at 2 m.p.h. (3 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 969 mb.

Usagi Strengthens to a Typhoon East of Southern Vietnam

Former Tropical Storm Usagi strengthened into a typhoon east of southern Vietnam on Friday night.  At 10:00 p.m. EST on Friday the center of Typhoon Usagi was located at latitude 9.6°N and longitude 109.2°E which put it about 205 miles (335 km) east-southeast of Ho Chi Minh City, Vietnam.  Usagi was moving toward the west-southwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 977 mb.

A small circular eye was visible at the center of Typhoon Usagi on both conventional and microwave satellite imagery.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Typhoon Usagi.  The strongest rain bands were in the western half of the typhoon.  Storms near the core of Usagi were generating upper level divergence which was pumping mass away from the typhoon.  Winds to typhoon force extended out about 30 miles (50 km) from the center of circulation.  Winds to tropical storm force extended out about 125 miles (200 km) from the center.

Typhoon Usagi will move through an environment favorable for intensification during the next 24 hours.  Usagi will move over water where the Sea Surface Temperature is near 29°C.  It will move south of an upper level ridge.  The ridge will produce easterly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear, which will reduce the rate of intensification.  Typhoon Usagi will strengthen on Saturday.

The ridge north of Typhoon Usagi will steer the typhoon a little to the south of due west.  On its anticipated track the center of Typhoon Usagi will approach the Mouths of the Mekong River in about 24 hours.  Usagi will bring strong winds and drop heavy rain on southern Vietnam.  Winds to tropical storm force could affect Ho Chi Minh City.  There could be a storm surge of 6 to 9 feet (2 to 3 meters) along the coast.  Locally heavy rain could cause floods over portions of southern Vietnam and Cambodia.

Elsewhere over the Western North Pacific Typhoon Man-yi started to weaken southeast of Okinawa.  At 10:00 p.m. EST on Friday the center of Typhoon Man-yi was located at latitude 18.1°N and longitude 135.4°E which put it about 760 miles (1230 km) southeast of Okinawa.  Man-yi was moving toward the north at 5 m.p.h. (8 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 969 mb.

Tropical Storm Usagi Forms East of Vietnam

Tropical Storm Usagi formed over the South China Sea east of Vietnam on Thursday.  At 10:00 a.m. EST on Thursday the center of Tropical Storm Usagi was located at latitude 11.2°N and longitude 113.7°E which put it about 350 miles (565 km) east of Lien Huong, Vietnam.  Usagi was moving toward the west at 18 m.p.h. (29 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.

More thunderstorms developed near the center of former Tropical Depression 33W and the Japan Meteorological Agency designated the system as Tropical Storm Usagi.  Satellite imagery indicated that the inner end of a rainband was wrapping around the center of circulation.  Several other bands of showers and thunderstorms were in the western half of Tropical Storm Usagi.  Bands in the eastern half of the circulation consisted primarily of showers and low clouds.  An upper level ridge north Usagi was producing southeasterly winds which were blowing toward the top of the circulation.  Those winds were causing moderate vertical wind shear and they were the reason why the stronger thunderstorms were developing west of the center of circulation.  Storms near the center were producing upper level divergence which was pumping mass away to the west of the tropical storm.

Tropical Storm Usagi will move through an environment favorable for intensification during the next 24 to 36 hours.  Usagi will move over water where the Sea Surface Temperature is near 29°C.  It will continue to move south of an upper level ridge and moderate vertical wind shear will continue to affect Tropical Storm Usagi.  The wind shear will slow intensification, but Usagi will strengthen during the next day or so.  It could intensify into a typhoon during the next 36 hours.

The ridge north of Tropical Storm Usagi will steer the tropical storm on a track a little to the south of due west.  On its anticipated track the center of Tropical Storm Usagi will approach the coast of southern Vietnam in about 36 hours.  Usagi could make landfall on the portion of the coast between Cam Ranh and Vung Tau.  Tropical Storm Usagi will bring gusty winds and it could drop locally heavy rain over southern Vietnam and Cambodia.  Heavy rain could cause flash foods in some locations.

Elsewhere over the Western North Pacific, Typhoon Man-yi was moving away from the Marianas after causing power outages in southern Guam.  At 10:00 a.m. EST on Thursday the center of Typhoon Man-yi was located at latitude 13.5°N and longitude 137.8°E which put it about 1155 miles (1860 km) southeast of Okinawa.  Man-yi was moving toward the northwest at 21 m.p.h. (34 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 969 mb.

Man-yi Strengthens to a Typhoon Southwest of Guam

Former Tropical Storm Man-yi strengthened to a typhoon southwest of Guam on Wednesday.  At 10:00 p.m. EST on Wednesday the center of Typhoon Man-yi was located at latitude 11.1°N and longitude 141.1°E which put it about 300 miles (485 km) southwest of Guam.  Man-yi was moving toward the west-northwest at 27 m.p.h. (44 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. (170 km/h).  The minimum surface pressure was 973 mb.

Typhoon Man-yi strengthened quickly on Wednesday.  An inner band of thunderstorms wrapped around the center of circulation.  A small eye appeared intermittently on satellite imagery.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Other bands of showers and thunderstorms were revolving around the core of Typhoon Man-yi.  Storms near the core were generating upper level divergence which was pumping mass away from the typhoon.  Winds to typhoon force extended out about 40 miles (65 km) from the center of circulation.  Winds to tropical storm force extended out about 145 miles (230 km) from the center.

Typhoon Man-yi will move through an environment somewhat favorable for intensification on Thursday.  Man-yi 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 further intensification.  Typhoon Man-yi will move south of an upper level ridge.  The ridge will produce strong east-southeasterly winds which will blow toward the top of the circulation.  Those winds will produce moderate vertical wind shear.  The wind shear will inhibit upper level outflow to the east of the typhoon and they will slow the rate of intensification.  Despite the moderate vertical wind shear, Typhoon Man-yi is likely to strengthen during the next 24 hours and it could become the equivalent of a major hurricane.

The ridge will steer Typhoon Man-yi rapidly toward the northwest during the next 24 to 36 hours.  On its anticipated track Typhoon Man-yi will move quickly away from Guam and the Marianas.  Man-yi could move southeast of Okinawa this weekend.

Elsewhere over the rest of the Western North Pacific Ocean, Tropical Depression 33W was moving quickly westward over the South China Sea.  At 10:00 p.m. EDT on Wednesday the center of Tropical Depression 33W was located at latitude 11.1°N and longitude 116.2°E which put it about 505 miles (815 km) east of Cam Ranh, Vietnam.  It was moving toward the west at 25 m.p.h. (40 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 1004 mb.

Tropical Storm Man-yi Forms Southeast of Chuuk

Tropical Storm Man-yi formed southeast of Chuuk on Tuesday.  At 7:00 a.m. EST on Tuesday the center of Tropical Storm Man-yi was located at latitude 4.8°N and longitude 154.2°E which put it about 245 miles (395 km) southeast of Chuuk.  Man-yi was moving toward the west 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 1000 mb.

A Tropical Storm Watch was issued for Guam and Rota.  Tropical Storm Warnings were in effect for Chuuk Lagoon, Lukunor, Losap, Fananu, Ulul, Pulawat and Satawal.  Typhoon Watches were issued for Faraulep and Pulawat.

Tropical Depression 34W exhibited greater organization on satellite imagery and the Japan Meteorological Agency designated the system as Tropical Storm Man-yi.  More thunderstorms developed near the center of circulation.  The strongest thunderstorms were occurring in a band west of the center.  Other bands of showers and thunderstorms were developing around Tropical Storm Man-yi.  Storms near the center of circulation were generating upper level divergence which was pumping mass away to the west of the tropical storm.

Tropical Storm Man-yi will move through an environment favorable for intensification.  Man-yi will move over water where the Sea Surface Temperature is near 29°C.  It will move south of an upper level ridge.  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 Man-yi will intensify and it could strengthen into a typhoon in a day or two.

The upper level ridge will steer Tropical Storm Man-yi toward the west-northwest during the next 12 to 24 hours.  A weakness is forecast to develop in the ridge, which would allow Man-yi to move more toward the northwest.  On its anticipated track Tropical Storm Man-yi will move near Chuuk in 12 to 24 hours.  It will bring gusty winds and drop heavy rain.  Man-yi could be southeast of Guam in 36 to 48 hours.

Elsewhere over the Western North Pacific Ocean Tropical Depression 33W was dropping rain over parts of the central Philippines and Tropical Depression Toraji was moving over the Gulf of Thailand.  At 4:00 a.m. EST on Tuesday the center of Tropical Depression 33W was located at latitude 10.9°N and longitude 126.8°E which put it about 160 miles (260 km) east-southeast of Tacloban, Philippines.  It was moving toward the west-northwest at 13 m.p.h. (20 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 1004 mb.

At 4:00 a.m. EDT the center of Tropical Depression Toraji was located at latitude 8.1°N and longitude 101.1°E which put it about 100 miles (160 km) east of Hua Sai, Malaysia.  Toraji was moving toward the west-southwest at 5 m.p.h. (8 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 1002 mb.

Tropical Storm Teraji Develops East of Vietnam

Tropical Storm Teraji developed east of Vietnam on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Storm Teraji was located at latitude 11.1°N and longitude 110.1°E which put it about 100 miles (160 km) east of Lien Huong, Vietnam.  Teraji was moving toward the west at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1004 mb.

A distinct low level center of circulation developed in an area of thunderstorms over the South China Sea east of southern Vietnam on Saturday and the Japan Meteorological Agency designated the system as Tropical Storm Teraji.  The circulation around Teraji was exhibiting evidence of vertical wind shear.  The center of circulation was on the eastern edge of a cluster of thunderstorms.  Tropical Storm Teraji was south of an upper level ridge.  The ridge was producing easterly winds which were causing moderate vertical wind shear.  The stronger thunderstorms were occurring in bands west of the center of circulation, which was likely an effect of the wind shear.

The ridge north of Tropical Storm Teraji will steer the tropical storm westward into southern Vietnam.  On its anticipated track Teraji will move over southern Vietnam on Sunday.  Tropical Storm Teraji will move across southern Cambodia early next week.  Thunderstorms in rainbands in the western half of Teraji could drop locally heavy and floods could occur in some locations.

Elsewhere over the Western North Pacific Ocean Tropical Depression 34W formed southeast of Palau.  At 10:00 p.m. EST on Saturday the center of Tropical Depression 34W was located at latitude 6.6°N and longitude 135.5°E which put it about 90 miles (145 km) southeast of Palau.  It was moving toward the west-southwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts tot 45 m.p.h. (75 km/h).  The minimum surface pressure was 1004 mb.

Typhoon Yutu Brings Wind and Rain to Luzon

Typhoon Yutu brought wind and rain to Luzon on Monday.  At 5:00 p.m. EDT on Monday the center of Typhoon Yutu was located at latitude 16.8°N and longitude 122.4°E which put it about 45 miles (75 km east of Ilagan, Philippines.  Yutu was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 949 mb.

The center of Typhoon Yutu made landfall near Palanan Point on the northeast coast of Luzon late on Monday.  Yutu had a large circulation.  Winds to typhoon force extended out about 80 miles (130 km) from the center of circulation.  Winds to tropical storm force extended out about 270 miles (435 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Yutu was 17.8.  The Hurricane Size Index (HSI) was 25.5 and the Hurricane Wind Intensity Size Index (HWISI) was 43.3.  Typhoon Yutu is capable of causing widespread serious damage.

Typhoon Yutu could cause a storm surge of up to 10 feet (3 meters) on the northeast coast of Luzon.  It will also produce destructive winds as it moves across northern Luzon.  Yutu will move westward across Luzon.  It will move into the South China Sea south of Vigan, Philippines.  Typhoon Yutu will drop very heavy rain over parts of northern Luzon and flash flooding will be very likely.  Rapid runoff into the Cagayan River could cause it to flood.

Typhoon Yutu will move over the Sierra Madre mountains and the Cordillera Central when it moves across northern Luzon.  Those two mountain ranges will disrupt the lower levels of the circulation and Yutu will be weaker when it reaches the South China Sea.  Yutu could still be a typhoon when it moves back over water, but it may weaken to a tropical storm by then.

Typhoon Yutu will move around the western end of a ridge of high pressure over the Western North Pacific Ocean when it reaches the South China Sea.  Yutu will move toward the north when it reaches the western end of the ridge and it could approach China in four or five days.

Powerful Typhoon Yutu Threatens Northern Luzon

Powerful Typhoon Yutu continued to pose a threat to northern Luzon on Saturday.  At 11:00 p.m. EDT on Saturday the center of Typhoon Yutu was located at latitude 18.0°N and longitude 129.6°E which put it about 475 miles (765 km) east of Cape Engano, Philippines.  Yutu was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h).  The minimum surface pressure was 929 mb.

There were minor fluctuations in its intensity on Saturday, but Typhoon Yutu remains a very powerful tropical cyclone.  A circular eye is at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring of storms.  Several bands of showers and thunderstorms are revolving around the core of Typhoon Yutu.  Storms around the core are generating strong upper level divergence which is pumping mass away from the typhoon in all directions.

Typhoon Yutu has a large circulation.  Winds to typhoon force extend out about 75 miles (120 km) from the center of circulation.  Winds to tropical storm force extend out about 250 miles (400 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Yutu is 31.6.  The Hurricane Size Index (HSI) is 28.3 and the Hurricane Wind Intensity Size Index (HWISI) is 59.9.  Typhoon Yutu is capable of causing wide spread significant damage.

Typhoon Yutu will continue to move south of a ridge of high pressure over the Western North Pacific Ocean.  The ridge will steer Yutu in a generally westerly direction for another 36 to 48 hours.  On its anticipated track Typhoon Yutu will reach northern Luzon in about 36 to 42 hours.  Yutu will create a storm surge at the coast.  It will cause significant wind damage over northern Luzon.  Yutu will also drop locally heavy rain and cause flash floods over parts of northern Luzon.

Powerful Typhoon Yutu Churns Toward Northern Luzon

Powerful Typhoon Yutu churned toward northern Luzon on Friday.  At 5:00 p.m. EDT on Friday the center of Typhoon Yutu was located at latitude 17.7°N and longitude 135.9°E which put it about 900 miles (1450 km) east of Cape Engano, Philippines.  Yutu was moving toward the west-northwest at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 920 mb.

After completing an eyewall replacement cycle Typhoon Yutu strengthened again on Friday.  Yutu is once again the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.  The eyewall replacement cycle also caused an increase in the size of Typhoon Yutu’s circulation.  Winds to typhoon force extend out about 80 miles (130 km) from the center of circulation.  Winds to tropical storm force extend out about 260 miles (420 km) from the center.  The Hurricane Intensity Index (HII) is 35.0.  The Hurricane Size Index (HSI) is 28.9 and the Hurricane Wind Intensity Size Index (HWISI) is 63.9.

Typhoon Yutu has a large, very well organized circulation and it will remain in an environment capable of supporting a powerful typhoon for several more days.  Yutu will move over water where the Sea Surface Temperature is near 31°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Yutu could strengthen a little more during the next 12 to 24 hours.  At some point another rainband is likely to wrap around the existing eye and eyewall, and another eyewall replacement cycle could occur.  If there is another eyewall replacement cycle, then Yutu would weaken, at least temporarily.

Typhoon Yutu will move south of a ridge of high pressure over the Western North Pacific Ocean.  The ridge will steer Yutu in a generally westward direction.  On its anticipated track Typhoon Yutu could reach northern Luzon in about four days.  Yutu is very likely to be a strong typhoon when it approaches Luzon.