Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Tropical Depression Forms South of Hainan Island

A tropical depression formed just to the south of Hainan Island on Friday night. At 11:00 p.m. EDT on Friday the center of Tropical Depression 05W was located at latitude 18.3°N and longitude 109.5°E which put it about 35 miles (55 km) south of Sanya, China. The depression was moving toward the west at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1000 mb.

Thunderstorms developed closer to the center of a low pressure system south of Hainan Island on Friday night and both the Japan Meteorological Agency and the Joint Typhoon Warning Center designated the system as a tropical depression. The distribution of thunderstorms around Tropical Depression 05W was asymmetrical. The strongest thunderstorms were occurring in bands southwest of the center of the tropical depression. Bands in the other parts of the circulation consisted primarily of showers and lower clouds. An upper level ridge centered over southern China was producing moderate northeasterly winds that were blowing toward the top of the depression. Those winds were causing moderate vertical wind shear and they were also causing the asymmetrical distribution of thunderstorms.

The center of Tropical Depression 05W will move near Hainan Island during the next few hours. The northern half of the circulation around the tropical depression will be over Hainan Island, which will inhibit intensification. Tropical Depression 05W will move into an environment favorable for intensification when it moves west of Hainan Island. The tropical depression will move over an area where the Sea Surface Temperatures are near 30°C. The upper level ridge over southern China will continue to produce moderate vertical wind shear. Even with the moderate wind shear, Tropical Depression 05W is likely to intensify to a tropical storm during the next 24 hours.

Tropical Depression 05W will move around the southern part of a subtropical high pressure system over the Western North Pacific Ocean during the next 36 hours. The high pressure system will steer the tropical depression toward the west-northwest. On its anticipated track the center of Tropical Depression 05W will pass near the southern part of Hainan Island. Since the strongest thunderstorms are in the southwestern part of the circulation, the tropical depression will cause mainly gustier winds over Hainan Island. Tropical Depression 05W could approach northern Vietnam in 24 hours. It could bring gusty winds and locally heavy rain to parts of northern Vietnam. Heavy rain could cause flash floods in some locations.

Tropical Storm Choi-wan Moves Toward Taiwan

Tropical Storm Choi-wan moved toward Taiwan on Thursday. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Choi-wan was located at latitude 20.0°N and longitude 118.9°E which put it about 185 miles (300 km) south-southwest of Taiwan. Choi-wan was moving toward the north-northeast at 10 m.p.h. (16 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 1002 mb.

Tropical Storm Choi-wan turned toward the north-northeast on Thursday which put it on a track towards southern Taiwan. The distribution of thunderstorms around Choi-wan was asymmetrical. The strongest thunderstorms were occurring in bands in the southwestern quadrant of Tropical Storm Choi-wan. Bands in the other quadrants of Choi-wan consisted primarily of showers and lower clouds. The distribution of wind speeds around Tropical Storm Choi-wan was also asymmetrical. Winds to tropical storm force extended out 125 miles (200 km) on the western side of Choi-wan. Winds to tropical storm force only extended out 65 miles (105 km) on the eastern side of the circulation.

Tropical Storm Choi-wan will move through an area that is mostly unfavorable for intensification during the next 36 hours. The center of Choi-wan will move over an area where the Sea Surface Temperatures are near 30°C. However, an upper level ridge centered over southern China will produce moderate northeasterly winds that will blow toward the top of the tropical storm. Those winds will cause moderate vertical wind shear and they are already responsible for the asymmetrical distribution of thunderstorms. The moderate vertical wind shear will likely prevent intensification of Tropical Storm Choi-wan.

Tropical Storm Choi-wan will move around the northwestern part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Choi-wan toward the north-northeast during the next 24 hours. On its anticipated track the center of Tropical Storm Choi-wan will reach southern Taiwan in 12 hours. Choi-wan could drop locally heavy rain over parts of southern Taiwan. Flash floods could occur in some locations. Tropical Storm Choi-wan could approach the southern Ryuku Islands in 24 hours. Choi-wan could bring a period of gusty winds to southern Taiwan and the southern Ryukyu Islands.

Tropical Storm Choi-wan Drops Rain on Luzon

Tropical Storm Choi-wan dropped rain on parts of Luzon around Manila on Wednesday. At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Choi-wan was located at latitude 15.5°N and longitude 119.6°E which put it about 85 miles (135 km) west-northwest of Manila, Philippines. Choi-wan was moving toward the northwest at 16 m.p.h. (26 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 1002 mb.

The center of Tropical Storm Choi-wan passed just south of Manila before the tropical storm moved west of Luzon. Bands near the center of Choi-wan dropped rain on parts of Luzon near Manila. Other bands in the southern half of Tropical Storm Choi-wan dropped rain on Mindoro. Choi-wan was still producing a few winds that were blowing at tropical storm force, but Manila did not report any winds that were that strong.

Tropical Storm Choi-wan exhibited an organized circulation on Wednesday afternoon. The inner end of a rainband wrapped around the western, southern and eastern sides of the center of Choi-wan. Other bands of thunderstorms were in the southern half of the tropical storm. Bands in the northern half of Tropical Storm Choi-wan consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 35 miles (55 km) from the center of Choi-wan.

Tropical Storm Choi-wan will move through an area that is marginally favorable for intensification during the next 24 hours. The center of Choi-wan will move over the South China Sea where the Sea Surface Temperatures are near 30°C. However, an upper level ridge centered over southern China will cause moderate vertical wind shear. The wind shear will limit the potential for intensification, but Tropical Storm Choi-wan could get a little stronger during the next 24 hours.

Tropical Storm Choi-wan will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Choi-wan toward the north during the next 24 hours. On its anticipated track the center of Tropical Storm Choi-wan will move northwest of Luzon during the next 24 hours. Choi-wan will turn toward the northeast on Friday after it moves around the western end of the high pressure system. Tropical Storm Choi-wan could approach the southern end of Taiwan in 36 hours.

Tropical Storm Choi-wan Brings Rain to Philippines

Tropical Storm Choi-wan brought rain to the central Philippines on Tuesday. At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Choi-wan was located at latitude 13.1°N and longitude 121.9°E which put it about 155 miles (250 km) southeast of Manila, Philippines. Choi-wan was moving toward the west-northwest at 17 m.p.h. (28 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1002 mb.

The center of Tropical Storm Choi-wan made an initial landfall on the east coast of Samar and then it moved west-northwest across the central Philippines. Choi-wan moved across the Sibuyan Sea and it was centered southeast of Manila on Tuesday night. The circulation around Tropical Storm Choi-wan weakened when the center passed over Samar, but it was still producing a small area of tropical storm force winds. Winds to tropical storm force extended out 35 miles (55 km) from the center of Choi-wan.

Tropical Storm Choi-wan dropped locally heavy rain over parts of Samar, Masbate, Panay and Mindoro on Tuesday. An upper level ridge centered over southern China was producing northeasterly winds which were blowing toward the top of Choi-wan. Those winds were producing moderate vertical wind shear and they causing the heavier rain to fall in bands in the southern half of Tropical Storm Choi-wan. Bands in the northern half of the tropical storm consisted primarily of showers and lower clouds.

Tropical Storm Choi-wan will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Choi-wan toward the north-northwest during the next several days. On its anticipated track the center of Tropical Storm Choi-wan could pass just south of Manila in 12 hours. Choi-wan could drop locally heavy rain on Mindoro and western Luzon. Heavy rain could cause flash floods in some locations.

Tropical Storm Choi-wan will move through an environment that is mostly unfavorable for intensification. Choi-wan will move over water where the Sea Surface Temperatures are near 30°C. However, the upper level ridge center over southern China will continue to cause moderate vertical wind shear. The wind shear will limit the potential for intensification. The eastern side of the circulation around Tropical Storm Choi-wan will be over Luzon during the next 24 hours, which will also be unfavorable for intensification.

Tropical Storm Choi-wan Nears the Philippines

Tropical Storm Choi-wan neared the central Philippines on Monday night. At 11:00 p.m. EDT on Monday the center of Tropical Storm Choi-wan was located at latitude 10.4°N and longitude 126.9°E which put it about 100 miles (160 km) east-southeast of Guiuan, Philippines. Choi-wan was moving toward the west-northwest at 11 m.p.h. (17 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 997 mb.

Tropical Storm Choi-wan was approaching Samar in the central Philippines on Monday night. An upper level ridge centered near Hong Kong was producing northeasterly winds that were blowing toward the top of Choi-wan. Those winds were causing moderate vertical wind shear and they were affecting the structure of the tropical storm. The stronger thunderstorms were occurring bands southwest of the center of Tropical Storm Choi-wan. The bands in the other parts of Choi-wan consisted mainly of showers and lower thunderstorms. Winds to tropical storm force extended out 65 miles (105 km) from the center of circulation.

Tropical Storm Choi-wan will move through an environment only marginally favorable for intensification during the next 12 hours. Choi-wan will move over water where the Sea Surface Temperatures are near 30°C. However, the upper level ridge will continue to cause moderate vertical wind shear. The wind shear will limit the potential for intensification. The center of Tropical Storm Choi-wan will move over land later on Tuesday.

Tropical Storm Choi-wan will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Choi-wan during the next 36 hours. On its anticipated track the center of Tropical Storm Choi-wan will reach Samar in 12 hours. Choi-wan will bring gusty winds and locally heavy rain to Samar. Heavy rain could cause flash floods in some locations. The center of Tropical Storm Choi-wan could reach the southeastern part of Luzon in 24 hours.

TD 04W Strengthens to Tropical Storm Choi-wan East of Mindanao

Tropical Depression 04W strengthened to Tropical Storm Choi-wan east of Mindanao on Sunday. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Choi-wan was located at latitude 8.2°N and longitude 130.4°E which put it about 260 miles (420 km) east of Mindanao. Choi-wan was moving toward the northwest at 9 m.p.h. (15 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 997 mb.

The circulation around former Tropical Depression 04W exhibited more organization on Sunday night and the Japan Meteorological Agency named the system as Tropical Storm Choi-wan. Although the circulation around Choi-wan exhibited more organization, the distribution of thunderstorms was asymmetrical. The strongest thunderstorms were occurring in bands in the western side of Tropical Storm Choi-wan. Bands in the eastern half of the tropical storm consisted of showers and lower clouds. Storms west of the center of Choi-wan generated upper level divergence that pumped mass away to the west and south of the tropical storm. Winds to tropical storm force extended out 85 miles (135 km) from the center of circulation.

Tropical Storm Choi-wan will move through an environment favorable for intensification during the next 24 hours. Choi-wan 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 northeast of the Philippines. The ridge will produce easterly winds which will blow toward the top of the tropical storm. Those winds are the reason for the asymmetrical distribution of thunderstorms and they will continue to cause vertical wind shear. The wind shear will not be enough to prevent intensification, but the shear will limit the rate of intensification. Tropical Storm Choi-wan will likely intensify during the next 24 hours.

Tropical Storm Choi-wan will move around the western side of a subtropical high pressure system over the Western North Pacific Ocean. The high will steer Choi-wan toward the northwest during the next 36 hours. On its anticipated track Tropical Storm Choi-wan could approach the central Philippines in 36 hours.

Tropical Depression 04W Forms Southwest of Palau

Tropical Depression 04W formed southwest of Palau on Saturday. At 11:00 p.m. EDT on Saturday the center of Tropical Depression 04W was located at latitude 6.8°N and longitude 133.5°E which put it about 75 miles (120 km) southwest of Palau. It was moving toward the west-northwest at 8 m.p.h. (13 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.

The circulation around Tropical Depression 04W was still organizing on Saturday night. Bands of thunderstorms were revolving around the center of the depression. The strongest rainbands were in the western half of the circulation. Bands on the eastern side of the tropical depression consisted mainly of showers and lower clouds. Storms near the center of circulation began to generate upper level divergence that pumped mass away to the west and north of the depression.

Tropical Depression 04W will move through an environment favorable for intensification during the next 24 hours. The tropical depression will move over water where the Sea Surface Temperatures are near 30°C. It will move under the southern side of an upper level ridge east of the Philippines. The ridge will produce easterly winds which will blow toward the top of the depression. Those winds will cause vertical wind shear. The wind shear will not be enough to prevent intensification, but the shear will limit the rate of intensification. Tropical Depression 04W will likely intensify into a tropical storm during the next 24 hours.

Tropical Depression 04W will move around the western side of a subtropical high pressure system over the Western North Pacific Ocean. The high will steer the tropical depression toward the northwest during the next 48 hours. On its anticipated track Tropical Depression 04W will move farther away from Palau. The tropical depression is forecast to pass east of the Philippines.

Tropical Depression Drops Rain on Mindanao

Tropical Depression 03W dropped rain on Mindanao on Thursday. At 11:00 p.m. EDT on Thursday the center of Tropical Depression 03W was located at latitude 7.7°N and longitude 124.7°E which put it about 45 miles (75 km) northwest of Davao, Philippines. The tropical depression was moving toward the west at 12 m.p.h. (19 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 1004 mb.

Tropical Depression 03W made landfall on the east coast of Mindanao near Manay on Thursday. The depression generated showers and thunderstorms as it moved over Mindanao. Some of the rainbands revolving around the center of the tropical depression dropped heavy rain over parts of Mindanao. The circulation around Tropical Depression 03W weakened steadily after it moved over land. It is likely to continue to weaken as it moves west across the southern Philippines.

Tropical Depression Forms East of Mindanao

Tropical Depression 03W formed east of Mindanao on Wednesday. At 5:00 p.m. EDT on Wednesday the center of Tropical Depression 03W was located at latitude 7.1°N and longitude 129.6°E which put it about 275 miles (475 km) east of Davao, Philippines. The tropical depression was moving toward the west-northwest 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.

More thunderstorms formed near the center of a small low pressure system east of Mindanao on Wednesday and the Joint Typhoon Warning Center designated the system as Tropical Depression 03W. More thunderstorms were also forming in bands that were revolving around center of the depression. Storms near the center of circulation were began to generate upper level divergence that pumped mass away from the tropical depression.

Tropical Depression 03W will move through an environment favorable for intensification during the next 24 hours. The depression will move over water where the Sea Surface Temperatures are near 30°C. It will move under the middle of a small upper level ridge east of the Philippines. The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear. Tropical Depression will intensify during the next 24 hours and it is likely to strengthen to a tropical storm.

Tropical Depression 03W will move south of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer the depression toward the west-northwest during the next 48 hours. On its anticipated track, Tropical Depression 03W will approach the east coast of Mindanao in a little over 24 hours. It will likely be a tropical storm when it approaches the coast. The system will drop locally heavy rain over Mindanao and flash floods could occur.

Typhoon Surigae Moves away from the Philippines

Typhoon Surigae started to move away from the Philippines on Wednesday. At 5:00 p.m. EDT on Wednesday the center of Typhoon Surigae was located at latitude 19.6°N and longitude 124.9°E which put it about 240 miles (385 km) east-northeast of Aparri, Philippines. Surigae was moving toward the north at 6 m.p.h. (10 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 952 mb.

Typhoon Surigae weakened slowly on Wednesday as it started to move farther away from the Philippines. A large circular eye with a diameter of 70 miles (110 km) was present at the center of Surigae. The eye was surrounded by a ring of strong thunderstorms and the stronger winds were occurring in that ring of storms. Several bands of showers and thunderstorms were revolving around the core of Typhoon Surigae. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

Typhoon Surigae still had a large circulation on Wednesday. Winds to typhoon force extended out 60 miles (95 km) from the center of Surigae. Winds to tropical storm force extended out 200 miles (320 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Surigae was 22.1. The Hurricane Size Index (HSI) was 22.1 and the Hurricane Wind Intensity Size Index (HWISI) was 44.2. Surigae was still the equivalent of a major hurricane.

Typhoon Surigae will move into an environment that will become less favorable for a strong typhoon during the next several days. Surigae will move over cooler water northeast of the Philippines where the Sea Surface Temperatures is near 26°C. In addition, an upper level trough over China will move toward Typhoon Surigae. The trough will produce westerly winds which will blow toward the top of the typhoon. Those winds will cause the vertical wind shear to increase. The combination of cooler water and more wind shear will cause Typhoon Surigae to weaken during the next 48 hours.

The upper level trough will steer Typhoon Surigae toward the east-northeast during the next several days. On its anticipated track Surigae will move away from the Philippines and it will stay southeast of Taiwan and the Ryukyu Islands. Surigae could approach Iwo To by the end of the weekend.