Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Tropical Storm Lionrock Forms Southeast of Hainan

Tropical Storm Lionrock formed over the South China Sea southeast of Hainan on Thursday. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Lionrock was located at latitude 17.5°N and longitude 111.0°E which put it about 95 miles (150 km) southeast of Lingshui, China. Lionrock was moving toward the north-northwest 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 994 mb.

The circulation around a low pressure system over the South China Sea strengthened on Thursday and the Japan Meteorological Agency designated the system as Tropical Storm Lionrock. There was a broad center of circulation in the middle of Tropical Storm Lionrock. Many of the thunderstorms were occurring in bands northeast and southwest of the broad center. Storms in the bands generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 150 miles (240 km) on the eastern side of Lionrock. Winds to tropical storm force extended out 75 miles (120 km) on the western side of the circulation.

Tropical Storm Lionrock will move through an environment somewhat favorable for intensification during the next 24 hours. Lionrock will move over water where the Sea Surface Temperatures are near 29˚C. It will move under the eastern side of a small upper level ridge. The ridge will produce northeasterly winds that will blow toward the top of Lionrock’s circulation. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. Tropical Storm Lionrock is likely to intensify slowly during the next 24 hours because of the broad center of circulation.

Tropical Storm Lionrock will move around the southwestern part of a subtropical high pressure system over the Western North Pacific Ocean during the next 24 hours. The subtropical high will steer Lionrock toward the north-northwest. On its anticipated track the center of Tropical Storm Lionrock will reach Hainan in 24 hours. Lionrock will bring gusty winds and locally heavy rain to Hainan. Heavy rain could cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, a tropical depression formed east of the Philippines. At 5:00 p.m. EDT on Thursday the center of the tropical depression was located at latitude 13.3°N and longitude 129.7°E which put it about 400 miles (645 km) east of Legazpi, Philippines. The tropical depression was moving toward the east-northeast 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 1002 mb.

Typhoon Mindulle Passes South of Tokyo

Typhoon Mindulle passed south of Tokyo on Thursday. At 5:00 p.m. EDT on Thursday the center of Typhoon Mindulle was located at latitude 31.1°N and longitude 140.0°E which put it about 340 miles (545 km) south of Tokyo, Japan. Mindulle was moving toward the northeast at 17 m.p.h. (28 km/h). The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 969 mb.

The core of Typhoon Mindulle passed well to the south of Tokyo on Thursday. However, the circulation around Typhoon Mindulle was so large, that bands of showers and thunderstorms on the northern periphery of Mindulle were bringing gusty winds and rain to parts of Honshu. Winds to typhoon force extended out 130 miles (210 km) on the eastern side of Typhoon Mindulle. Winds to typhoon force extended out 75 miles in the western half of Mindulle. Winds to tropical storm force extended out 310 miles (500 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 13.9. The Hurricane Size Index (HSI) was 37.6 and the Hurricane Wind intensity Size Index (HWISI) was 51.5.

Typhoon Mindulle weakened as it moved over cooler water and into a region where westerly winds in the upper levels caused more vertical wind shear. A larger eye was present at the center of Mindulle, but breaks were developing in the ring of thunderstorms around the eye. The upper level westerly winds in the middle latitudes were beginning to affect the structure of Typhoon Mindulle. Those winds were blowing toward the top of Mindulle’s circulation and they were causing increasing vertical wind shear. The strongest thunderstorms were occurring in bands north and east of the center of the typhoon. Bands south and west of the center consisted primarily of showers and lower clouds. The combination of cooler water and more wind shear was causing Typhoon Mindulle to start a transition to an extratropical cyclone.

The westerly winds in the upper levels will steer Typhoon Mindulle quickly toward the northeast during the next 48 hours. On its anticipated track the core of Mindulle will pass well to the east of Honshu and Hokkaido. Bands on the northern side of Typhoon Mindulle could bring gusty winds and heavy rain to coastal parts of northern Honshu and eastern Hokkaido. Big waves will affect shipping southeast of Japan. Mindulle will weaken gradually during the next 48 hours while it makes a transition to an extratropical cyclone.

Typhoon Mindulle Strengthens Back to Equivalent of a Major Hurricane

Typhoon Mindulle strengthened back to the equivalent of a major hurricane west-southwest of Iwo To on Tuesday. At 5:00 p.m. EDT on Tuesday the center of Typhoon Mindulle was located at latitude 23.0°N and longitude 135.6°E which put it about 390 miles (630 km) west-southwest of Iwo To. Mindulle was moving toward the north at 7 m.p.h. (11 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 950 mb.

Typhoon Mindulle strengthened back to the equivalent of a major hurricane after it completed several Eyewall Replacement Cycles. A large circular eye with a diameter of 45 miles (75 km) was present at the center of Typhoon Mindulle. 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 Mindulle. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Mindulle grew even larger after it completed the Eyewall Replacement Cycles. Winds to typhoon force extended out 70 miles (110 km) from the center of Mindulle. Winds to tropical storm force extended out 235 miles (380 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 22.1. The Hurricane size Index (HSI) was 27.4 and the Hurricane Wind Intensity Size Index (HWISI) was 49.5.

Typhoon Mindulle will move through an environment capable of sustaining a powerful typhoon during the next 36 hours. Mindulle will move over water where the Sea Surface Temperatures are near 29˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Mindulle could strengthen gradually during the next 36 hours.

Typhoon Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next 48 hours. The high pressure system will steer Mindulle toward the north during the next 24 hours. Typhoon Mindulle will start to move toward the northeast after it moves around the western end of the high. On its anticipated track Typhoon Mindulle will pass west of Iwo To during the next 24 hours. Mindulle cold be south of Tokyo in 48 hours.

Typhoon Mindulle Develops Concentric Eyewalls

Large Typhoon Mindulle developed concentric eyewalls southwest of Iwo To on Sunday. At 11:00 p.m. EDT on Sunday the center of Typhoon Mindulle was located at latitude 19.9°N and longitude 136.4°E which put it about 445 miles (720 km) southwest of Iwo To. Mindulle moving toward the north at 3 m.p.h. (5 km/h). The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 150 m.p.h. (240 km/h). The minimum surface pressure was 947 mb.

Typhoon Mindulle developed concentric eyewalls on Sunday when the inner end of a rainband wrapped around an existing eye and eyewall. When the larger outer eyewall formed, much of the low level convergence of air shifted to the outer eyewall. The inner eyewall began to weaken because there was less low level convergence into it. Since the strongest winds were occurring in the existing inner eyewall, the maximum wind speed decreased when it weakened. The inner eyewall was still present, although it was much weaker. There was a break in the northwestern part of the outer eyewall. The existence of the two eyewalls was disrupting the inner core of Typhoon Mindulle.

The ongoing Eyewall Replacement Cycle was causing the circulation around Typhoon Mindulle to get larger. Winds to typhoon force extended out 65 miles (105 km) from the center of Mindulle. Winds to tropical storm force extended out 205 miles (330 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 23.6. The Hurricane size Index (HSI) was 23.2 and the Hurricane Wind Intensity Size Index (HWISI) was 46.8.

Typhoon Mindulle will move through an environment capable of sustaining a powerful typhoon during the next 36 hours. Mindulle will move over water where the Sea Surface Temperatures are near 30˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. The ongoing Eyewall Replacement Cycle will likely cause Typhoon Mindulle to weaken during the next 12 hours. If the inner eyewall dissipates and the outer eyewall becomes more well developed, then Mindulle could strengthen again. Typhoon Mindulle will move slowly. The strong winds in Mindulle could mix cooler water to the surface. Cooler water and an Eyewall Replacement Cycle could limit the potential for Typhoon Mindulle to intensify.

Typhoon Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next several days. The high will steer Mindulle slowly toward the north-northwest during the next 36 hours. On its anticipated track Typhoon Mindulle could be west of Iwo To in 48 hours. Mindulle could be south of Tokyo in four days.

Typhoon Mindulle Rapidly Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Mindulle rapidly intensified to the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Saturday night. At 11:00 p.m. EDT on Saturday the center of Typhoon Mindulle was located at latitude 18.7°N and longitude 136.8°E which put it about 510 miles (825 km) southwest of Iwo To. Mindulle moving toward the northwest at 4 m.p.h. (6 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 915 mb.

Typhoon Mindulle continued to intensify rapidly over the Western North Pacific Ocean on Saturday night. A circular eye with a diameter of 18 miles (29 km) was present at the center of Mindulle. 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 Mindulle. Storms near the core generated strong upper level divergence that pumped large quantities of mass away from the typhoon. The removal of large amounts of mass allowed the surface pressure to decrease rapidly.

The circulation around Typhoon Mindulle was more than twice as large as the circulation of Hurricane Sam which was over the Atlantic Ocean. Winds to typhoon force extended out 50 miles (80 km) from the center of Mindulle. Winds to tropical storm force extended out 210 miles (340 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 35.0. The Hurricane Size Index (HSI) was 19.4 and the Hurricane Wind Intensity Size Index (HWISI) was 54.4.

Typhoon Mindulle will move through an environment capable of sustaining a powerful typhoon during the next 36 hours. Mindulle will move over water where the Sea Surface Temperatures are near 30˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Mindulle may be near its peak intensity. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. That structure would start an eyewall replacement cycle that could cause Typhoon Mindulle to weaken. Typhoon Mindulle will move slowly. The strong winds in Mindulle could mix cooler water to the surface. That would also cause Mindulle to weaken.

Typhoon Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next several days. The high will steer Mindulle slowly toward the northwest during the next several days. On its anticipated track Typhoon Mindulle could be west of Iwo To in three days.

Typhoon Mindulle Rapidly Intensifies to Equivalent of a Major Hurricane

Typhoon Mindulle rapidly intensified to the equivalent of a major hurricane on Saturday. At 11:00 a.m. EDT on Saturday the center of Typhoon Mindulle was located at latitude 18.3°N and longitude 137.3°E which put it about 525 miles (850 km) south-southwest of Iwo To. Mindulle moving toward the north-northwest at 16 m.p.h. (26 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 942 mb.

Typhoon Mindulle rapidly intensified to the equivalent of a major hurricane over the Western North Pacific Ocean on Saturday. A circular eye was present at the center of Mindulle. 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 Mindulle. Storms near the core generated upper level divergence that pumped large quantities of mass away from the typhoon. The removal of large amounts of mass allowed the surface pressure to decrease rapidly.

The circulation around Typhoon Mindulle was about twice as large as the circulation of Hurricane Sam which was over the Atlantic Ocean. Winds to typhoon force extended out 45 miles (75 km) from the center of Mindulle. Winds to tropical storm force extended out 160 miles (260 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 25.1. The Hurricane Size Index (HSI) was 16.0 and the Hurricane Wind Intensity Size Index (HWISI) was 41.1.

Typhoon Mindulle will move through an environment favorable for intensification during the next 24 hours. Mindulle will move over water where the Sea Surface Temperatures are near 30˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Mindulle will continue to intensify during the next 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. That structure would start an eyewall replacement cycle that could cause Typhoon Mindulle to weaken.

Typhoon Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next several days. The high will steer Mindulle slowly toward the northwest during the next several days. On its anticipated track Typhoon Mindulle could be west of Iwo To in three or four days.

Mindulle Strengthens to a Typhoon

Former Tropical Storm Mindulle strengthened to a typhoon south-southwest of Iwo To on Friday night. At 11:00 p.m. EDT on Friday the center of Typhoon Mindulle was located at latitude 17.1°N and longitude 138.1°E which put it about 565 miles (910 km) south-southwest of Iwo To. Mindulle moving toward the northwest at 4 m.p.h. (6 km/h). The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (150 km/h). The minimum surface pressure was 978 mb.

Former Tropical Storm Mindulle strengthened to a typhoon over the Western North Pacific Ocean on Friday night. A circular eye developed at the center of Typhoon Mindulle. A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Mindulle. Storms near the core generated upper level divergence that pumped mass away from the typhoon. Winds to typhoon force extended out 30 miles (50 km) from the center of Mindulle. Winds to tropical storm force extended out 145 miles (230 km) from the center of circulation.

Typhoon Mindulle will move through an environment favorable for intensification during the next 48 hours. Mindulle will move over water where the Sea Surface Temperatures are near 30˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Mindulle will continue to intensify during the next 48 hours. Mindulle could strengthen to the equivalent of a major hurricane.

Typhoon Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next several days. The high will steer Mindulle slowly toward the northwest during the next several days. On its anticipated track Typhoon Mindulle could be southwest of Iwo To by the end of the weekend.

Tropical Storm Mindulle Brings Wind and Rain to Marianas, Dianmu Hits Vietnam

Tropical Storm Mindulle brought wind and rain to the Marianas on Thursday and Tropical Storm Dianmu hit Vietnam. At 11:00 a.m. EDT on Thursday the center of Tropical Storm Mindulle was located at latitude 14.1°N and longitude 142.3°E which put it about 175 miles (280 km) west-northwest of Guam. Mindulle moving toward the west-northwest at 23 m.p.h. (37 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 Mindulle brought wind and rain to the Marianas including Guam on Thursday. Tropical Storm Warnings were in effect for Guam, Rota, Tinian and Saipan. Mindulle was intensifying as it moved across the Marianas. More thunderstorms developed about the center of circulation. Bands of showers and thunderstorms were revolving the center of Tropical Storm Mindulle. Storms near the center generated upper level divergence that pumped mass away from the tropical storm. The strongest winds were occurring in the northeastern part of Mindulle. Winds to tropical storm force extended out 150 miles (240 km) in the northeastern quadrant to Mindulle.

Tropical Storm Mindulle will move through an environment favorable for intensification during the next few days. Mindulle will move over water where the Sea Surface Temperatures are near 30˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Storm Mindulle will continue to intensify during the next 36 hours. Mindulle could strengthen to a typhoon in 24 hours. Mindulle could intensify more rapidly after an inner core becomes more well developed. It could intensify to the equivalent of a major hurricane during the weekend.

Tropical Storm Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next several days. The high will steer Mindulle toward the northwest during the next 48 hours. On its anticipated track Tropical Storm Mindulle will move quickly away from the Marianas. Mindulle could approach the Ryukyu Islands in a few days.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Dianmu bought wind and rain to central Vietnam. At 11:00 a.m. EDT on Thursday the center of Tropical Storm Dianmu was located at latitude 15.4°N and longitude 108.3°E which put it about 15 miles (25 km) southeast of Tam Ky, Vietnam. Dianmu was moving toward the 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 1000 mb. Tropical Storm Dianmu will weaken as it moves inlands over Southeast Asia. Dianmu will bring gusty winds and locally heavy rain to central Vietnam, southern Laos and northern Cambodia. Heavy rain could cause flash floods in some locations.

Tropical Depression 20W Forms Southeast of Guam

Tropical Depression Twenty-W formed southeast of Guam on Wednesday. At 11:00 a.m. EDT on Wednesday the center of Tropical Depression Twenty-W was located at latitude 11.5°N and longitude 148.1°E which put it about 305 miles (490 km) east-southeast of Guam. The tropical depression moving toward the west-northwest at 10 m.p.h. (16 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). T he minimum surface pressure was 1005 mb.

Tropical Depression Twenty-W developed over the Western North Pacific Ocean southeast of Guam on Wednesday. The circulation around the tropical depression was organizing quickly. Thunderstorms formed near the center of the tropical depression. Other thunderstorms developed in bands revolving around the center of circulation. Storms near the center began to generate upper level divergence that pumped mass away from the depression.

Tropical Depression Twenty-W will move through an environment favorable for intensification during the next few days. The tropical depression will move over water where the Sea Surface Temperatures are near 30˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Depression Twenty-W could strengthen to a tropical storm during the next 12 hours. It could intensify more rapidly after an inner core becomes more well developed. It could intensify to a typhoon within 36 hours.

Tropical Depression Twenty-W will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next several days. The high will steer the tropical depression toward the northwest during the next 36 hours. On its anticipated track the tropical depression could reach the Marianas in less than 24 hours. Tropical Depression Twenty-W could intensify to a tropical storm before it reaches the Marianas. It will bring gusty winds and locally heavy rain to the Marianas including Guam.

Elsewhere over the Western North Pacific Ocean, Tropical Depression Twentyone-W formed over the South China Sea east of Vietnam. At 11:00 a.m. EDT on Wednesday the center of Tropical Depression Twentyone-W was located at latitude 12.9°N and longitude 112.8°E which put it about 400 miles (605 km) east-southeast of Da Nang, Vietnam. The tropical depression moving toward the west-northwest at 13 m.p.h. (20 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). T he minimum surface pressure was 1005 mb. Tropical Depression Twentyone-W is forecast to move toward the west-northwest and to strengthen to a tropical storm. It could reach the coast of Vietnam south of Da Nang in about 24 hours.

Tropical Storm Chanthu Brings Gusty Winds and Rain to Japan

Tropical Storm Chanthu brought gusty winds and rain to parts of Japan on Friday. At 6:00 a.m. EDT on Friday the center of Tropical Storm Chanthu was located at latitude 33.7°N and longitude 130.6°E which put it about 10 miles (15 km) east of Fukuoka, Japan. Chanthu was moving toward the east-northeast at 17 m.p.h. (28 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 990 mb.

Tropical Storm Chanthu brought gusty winds to northern Kyushu and western Honshu on Friday. Winds to tropical storm force extended out 115 miles (185 km) from the center of Chanthu. The strongest winds were occurring in the parts of Chanthu’s circulation that were over water and in the mountains of western Japan. The heaviest rain was falling on the eastern side of Tropical Storm Chanthu.

Tropical Storm Chanthu will be steered quickly toward the east-northeast by the westerly winds in the middle latitudes. Tropical Storm Chanthu will move across Honshu during the next two days. The center of Tropical Storm Chanthu could be near Kyoto in 24 hours and near Tokyo in 36 hours. The upper level westerly winds will cause moderate vertical wind shear. The wind shear and movement across land will cause Chanthu to weaken gradually during the next 48 hours.