Tag Archives: Japan

Tropical Storm Chanthu Passes East of Tokyo

Tropical Storm Chanthu brought wind and rain to the east coast of Honshu as the center passed east of Tokyo on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Tropical Storm Chanthu was located at latitude 37.4°N and longitude 141.6°E which put it about 105 miles (170 km) northeast of Tokyo, Japan.  Chanthu was moving toward the north-northeast at 12 m.p.h. (19 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 995 mb.

Tropical Storm Chanthu is starting the transition from a tropical cyclone to an extratropical cyclone.  It is still moving over water where the Sea Surface Temperature (SST) is near 26°C, but Chanthu will move over colder water during the next 24 hours.  An upper level trough west of Japan will sweep northwesterly winds over the top of Tropical Storm Chanthu.  The increased vertical wind shear will tilt the circulation of Chanthu toward the northeast.  The trough also contains cooler air.  A combination of cooler SSTs, more vertical wind shear and cooler air aloft will alter the structure of Chanthu and it will begin to look more like an extratropical cyclone on Wednesday.

The upper level trough will steer Chanthu in a generally north-northeasterly direction during the next 24 hours.  On its anticipated track Tropical Storm Chanthu will move roughly parallel to the coast of Honshu.  Chanthu is expected to move across Hokkaido later on Wednesday.

The rainbands in Tropical Storm Chanthu are capable of producing locally heavy rainfall.  Some flooding is possible in eastern Honshu and Hokkaido.  Wind damage should be minimal although fishing boats and other vessels along the northeast coast of Japan will have to deal with wind and waves.

Tropical Storm Chanthu Forms South of Japan

A center of circulation consolidated near a cluster of thunderstorms south of Japan on Saturday and the system was designated as Tropical Storm Chanthu.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Chanthu was located at latitude 21.2°N and longitude 143.1°E which put it about 295 miles (475 km) south-southeast of Iwo To.  Chanthu was moving toward the northeast at 14 m.p.h. (23 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 998 mb.

Although a distinct center of circulation exists in the lower levels of Tropical Storm Chanthu, the storm is not well organized.  Southwesterly winds in the upper levels are causing vertical wind shear which is tilting the upper portion of the circulation toward the northeast.  Most of the thunderstorms associated with Tropical Storm Chanthu are occurring in the northeastern quadrant of the circulation.  Several broken rainbands extend into the southern portion of the circulation, but there are few thunderstorms in the western half of Chanthu.

Tropical Storm Chanthu is moving through an environment that is marginally favorable for intensification.  Chanthu is moving over water where the Sea Surface Temperature is near 30°C.  However, an upper level trough west of Chanthu is causing the southwesterly winds which are blowing across the top of the tropical storm.  Moderate vertical wind shear will inhibit intensification in the short term.  As Tropical Storm Chanthu moves farther north, it could move into a region where the upper level winds are not as strong.  If the vertical wind shear decreases, then Chanthu could intensify.

Winds from the upper level trough are steering Tropical Storm Chanthu toward the northeast.  As the tropical storm moves farther north, a subtropical ridge located east of Chanthu will steer it more toward the north.  On its anticipated track, the center of Tropical Storm Chanthu is expected to pass east of Iwo To in about 24 hours.  Tropical Storm Chanthu could be approaching the coast of Japan near Tokyo in about three or four days.

Tropical Storm Omais Forms over the Northern Marianas

A very broad area of low pressure developed enough of the characteristics of a tropical cyclone to be classified as Tropical Storm Omais on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Omais was located at latitude 19.5°N and longitude 146.2°E which put it about 380 miles (615 km) north-northeast of Guam.  Omais was moving toward the north at 3 m.p.h. (5 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 996 mb.

The circulation of Tropical Storm Omais is not well organized.  Several clusters of thunderstorms exist about 100 miles (160 km) east and south of the center of the very broad low pressure system.  No thunderstorms are occurring in the western half of the low or near the center of the circulation.  An inner core does not exist at this time and the strongest winds are occurring in the clusters of thunderstorms well removed from the center.

Tropical Storm Omais is in an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  The upper level environment is also somewhat favorable for intensification.  An upper level low is northwest of Omais and an upper level ridge is east of the tropical storm.  Those two features are generating southwesterly winds which are blowing over the top of Tropical Storm Omais.  The vertical wind shear is inhibiting the organization and intensification of Omais.

The environment should allow Tropical Storm Omais to intensify, but the large circulation will reduce the rate of intensification.  As the wind field contracts and the strongest winds move closer to the center of circulation, the structure of Tropical Storm Omais will move closely resemble a typical tropical cyclone.  When an inner core forms at the center of circulation, the rate of intensification may increase.

Tropical Storm Omais is near the western end of a subtropical ridge.  The steering currents are weak, but Omais is likely to move slowly toward the north in the short term.  A faster motion is expected over the weekend.  On its anticipated track Tropical Storm Omais will move near the northernmost Marianas and pass east of Iwo To.

Weakened Tropical Storm Nepartak Still Bringing Rain to Parts of China and Taiwan

Although Tropical Storm Nepartak was weakened significantly during its passage over the mountains on Taiwan, it is still producing heavy rain over portions of eastern China and Taiwan.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Nepartak was located at latitude 24.0°N and longitude 119.0°E which put it about 100 miles (160 km) east-southeast of Xiamen, China.  Nepartak was moving toward the northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 70 m.p.h. (115 km/h) and there were wind gusts to 85 m.p.h. (140 km/h).  The minimum surface pressure was 978 mb.

Typhoon Nepartak brought damaging winds and heavy rainfall to Taiwan when the core of the tropical cyclone passed over that area.  The mountains on Taiwan significantly disrupted the lower levels of the circulation.  There are some indications on satellite imagery that the upper portion of the circulation is located northwest of the surface center.  When a typhoon crosses Taiwan, the mountains can cause the original center of circulation to weaken and a new center can sometimes form over the water on the downstream side of the island.

In any case, crossing over Taiwan caused Nepartak to weaken to a tropical storm and the circulation no longer exhibits a tight inner core.  However, there are still rainbands that are producing heavy rain and wind speeds to almost typhoon force.   Because Nepartak no longer has a tight inner core, it is unlikely to intensify significantly before the centers moves into eastern China.

A ridge northeast of Nepartak is steering the tropical storm toward the northwest and that general motion is expected to continue for the next 12 to 24 hours.  After that time Nepartak is expected to turn toward the north.  On its anticipated track Tropical Storm Nepartak will make landfall in China between Xiamen and Fuqing on Saturday.

Tropical Storm Nepartak could produce locally heavy rainfall over portions of eastern China.  Some of that region has already received a lot of rain from other weather systems.  So, the potential for additional flooding is high in some areas.

Typhoon Nepartak Pounding Taiwan

Typhoon Nepartak is pounding Taiwan with strong winds and heavy rain.  The eye will make landfall during the next few hours near T’aitung.  At 5:00 p.m. EDT on Thursday the center of Typhoon Nepartak was located at latitude 22.7°N and longitude 121.4°E which put it about 185 miles (305 km) south of Taipei, Taiwan.  Nepartak was moving toward the west-northwest at 10 m.p.h. (16 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 926 mb.

Typhoon Nepartak is the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  The Hurricane Intensity Index (HII) for Nepartak is 31.5.  The Hurricane Size Index (HSI) is 20.5, and the Hurricane Wind Intensity Size Index (HWISI) is 52.0.  These indices mean that Typhoon Nepartak is capable of causing widespread significant damage as it crosses Taiwan.

In addition to the strong winds locally heavy rain could cause flash floods, especially in the mountains of Taiwan.

The circulation of Typhoon Nepartak is very well organized.  It has a well formed eye which is surrounded by a ring of strong thunderstorms.  Numerous rainbands are rotating around the typhoon.

The atmospheric environment is favorable for strong tropical cyclones.  The winds in the upper levels are weak and there is little vertical wind shear.  However, the mountains on Taiwan will disrupt the lower part of the circulation and Typhoon Nepartak will weaken significantly when it crosses the island.  It will take about 12 hours for the typhoon to move across Taiwan.  Nepartak could still be a typhoon when the center emerges over the Taiwan Strait on Friday.

Typhoon Nepartak is expected to also make landfall on the east coast of China between Xiamen and Fuzhou.  Although it will be much weaker, Nepartak could cause some wind damage when it reaches China.  However, heavy rain will be a greater risk because it cause significant flooding in parts of eastern China.

Dangerous Super Typhoon Nepartak Closing In On Taiwan

Dangerous Super Typhoon Nepartak closed in on Taiwan on Wednesday.  At 11:00 a.m. EDT on Wednesday the center of Typhoon Nepartak was located at latitude 20.5°N and longitude 126.3°E which put it about 480 miles (775 km) southeast of Taipei, Taiwan. Nepartak was moving toward the west-northwest at 19 m.p.h. (31 km/h).  The maximum sustained wind speed was 175 m.p.h. (280 km/h) and there were wind gusts to 210 m.p.h. (335 km/h).  The minimum surface pressure was 911 mb.

Typhoon Nepartak is the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.  The Hurricane Intensity Index (HII) for Nepartak was 40.3.  The Hurricane Size Index (HSI) was 18.8 and the Hurricane Wind Intensity Size Index (HWISI) was 59.1.  These indices mean that Typhoon Nepartak is capable of producing regional catastrophic damage.  As a point of comparison, Typhoon Nepartak is almost as strong as and slightly smaller than Hurricane Rita was when Rita was a Category 5 hurricane over the Gulf of Mexico in 2005.

The circulation of Typhoon Nepartak is very well organized.  It is symmetrical and winds to typhoon force extend out about 45 miles (75 km) from the center.  There is a very small eye at the center of Nepartak and the eye is surrounded by a ring of very strong thunderstorms.  The thunderstorms around the eye are generating strong upper level divergence which is offsetting the flow of mass into the typhoon near the surface.  The upper level divergence is allowing the pressure to stay low and strong winds to persist.  Spiral bands of thunderstorms are rotating around the core of the typhoon.

Typhoon Nepartak is in an ideal environment for a tropical cyclone.  It is moving over water where the Sea Surface Temperature (SST) is near 31°C.  The upper level winds are weak and there is almost no vertical wind shear.  Typhoon Nepartak is likely to maintain its intensity as it approaches the coast of Taiwan.

A subtropical ridge northeast of Nepartak is steering the typhoon toward the west-northwest and that general motion is expected to continue for another 24 to 36 hours.  On its anticipated track Typhoon Nepartak will make landfall along the central portion of the east coast of Taiwan in 12 to 18 hours.  After it moves across Taiwan, Nepartak is expected to make another landfall on the east coast of China.

Nepartak is a strong and dangerous typhoon.  It is capable of causing catastrophic damage over portions of Taiwan.  Nepartak will also produce very rainfall which is likely to cause flash floods and mudslides.  Nepartak will weaken when it moves over Taiwan, but it could still be a typhoon when it reaches the east coast of China.  Nepartak could also bring heavy rain and floods to parts of eastern China.

Typhoon Nepartak Rapidly Intensifies As It Moves Toward Taiwan

Typhoon Nepartak intensified rapidly on Tuesday and it is now the equivalent of a major hurricane.  At 11:00 a.m. EDT on Tuesday the center of Typhoon Nepartak was located at latitude 17.6°N and longitude 132.7°E which put it about 945 miles (1525 km) east-southeast of Taipei, Taiwan.  Nepartak was moving toward west-northwest at 21 m.p.h. (34 km/h).  The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (270 km/h).  The minimum surface pressure was 933 mb.

Tyyphoon Nepartak is the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  The Hurricane Intensity Index (HII) for Nepartak is 28.3.  The Hurricane Size Index (HSI) is 16.6 and the Hurricane Wind Intensity Size Index (HWISI) is 44.9.  These indices mean that Nepartak is capable of causing regionalized significant damage.

Typhoon Nepartak is very well organized.  It has a well formed eye, which is surround by a ring of strong thunderstorms.  Additional spiral bands of thunderstorms are rotating around the core of the circulation.  Nepartak is generating strong upper level divergence which is pumping out a lot of mass and is allowing the surface pressure to decrease rapidly.

Typhoon Nepartak is in an environment that is favorable for further intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 31°C.  The upper level winds are weak and there is very little vertical wind shear.  Nepartak could intensify into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale during the next 24 to 36 hours.  If one of the rainbands wraps around the existing eye, then concentric eyewalls could form.  If concentric eyewalls develop, then an ensuing eyewall replacement cycle could cause fluctuations in the intensity of Typhoon Nepartak.

A subtropical ridge northeast of Nepartak is steering the typhoon toward the west-northwest and that general motion is expected to continue for another day or two.  On its anticipated track Typhoon Nepartak could be very near the southernmost islands of Japan and the coast of Taiwan in 36 to 48 hours.  It is likely to be a strong typhoon at that time.  Nepartak could cause significant wind damage.  It could also produce heavy rain that could lead to flash floods and mudslides.

Nepartak Intensifies Into a Typhoon

Tropical Storm Nepartak intensified into a typhoon on Monday as it moved west of Guam.  At 11:00 p.m. EDT on Monday the center of Typhoon Nepartak was located at latitude 15.8°N and longitude 136.0°E which put it about 870 miles (1400 km) southeast of Okinawa.  Nepartak was moving toward the west-northwest at 20 m.p.h. (32 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 974 mb.

The Hurricane Intensity Index (HII) for Typhoon Nepartak was 10.4.  The Hurricane Size Index (HSI) was 3.7 and the Hurricane Wind Intensity Size Index (HWISI) was 14.1.

The structure of Typhoon Nepartak improved on Monday.  A circular area of strong thunderstorms developed at the center of circulation.  Those thunderstorms generated upper level divergence that pumped out mass in all directions, which allowed the surface pressure to decrease.  Several other bands of thunderstorms spiraled around the core of Nepartak.

Typhoon Nepartak is moving over water where the Sea Surface Temperature (SST) is near 31°C.  Nepartak moved into an area where the upper level winds were weaker and the vertical wind shear was reduced.  The combination of very warm water and reduced shear allowed Nepartak to organize and strengthen into a typhoon.  It is expected to remain in an environment favorable for intensification, and Nepartak will grow into a stronger typhoon during the next several days.

A ridge of high pressure northeast of Nepartak is steering the typhoon toward the west-northwest and that general motion is expected to continue for the next several days.  On its anticipated track Typhoon Nepartak could be approaching the southernmost islands of Japan and Taiwan in 48 to 60 hours.  It could be a very strong typhoon at that time.

Tropical Storm Nepartak Develops South of Guam

A center of circulation organized within an area of thunderstorms south of Guam and the system was designated Tropical Storm Nepartak.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Nepartak was located at latitude 12.2°N and longitude 141.4°E which put it about 215 miles (345 km) west-southwest of Guam.  Nepartak was moving northwest at 16 m.p.h. (26 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 989 mb.

The circulation of Tropical Storm Nepartak is still organizing.  A primary rainband wrapped around the center and a circular area of thunderstorms formed at the core of the circulation.  The area of thunderstorms is generating upper level divergence which is pumping out mass and allowing the surface pressure to decrease.  Winds to tropical storm force extend our about 100 miles (160 km) from the center of circulation.

An upper level low located north of Nepartak is producing southwesterly winds which area blowing over the top of the tropical storm.  Those winds are creating some vertical wind shear, which is slowing the intensification of Nepartak.  However, the upper low is also enhancing upper level divergence to the northeast of the tropical storm.  Nepartak is moving over water where the Sea Surface Temperature is near 30°C.  The environment is favorable for intensification and Nepartak could become a hurricane during the next several days.

A subtropical ridge located northeast of Nepartak is steering the tropical storm toward the northwest.  That general motion is expected to continue during the next few days.  On its anticipated track, Nepartak could be approaching the southernmost islands of Japan in three or four days.  It is likely to be a typhoon at that time.

In-Fa Weakens to a Tropical Storm on Its Way to Iwo To

In-Fa weakened below typhoon intensity on Tuesday as it moved toward Iwo To.  At 10:00 p.m. EST on Tuesday the center of Tropical Storm In-Fa was located at latitude 20.1°N and longitude 135.3°E which put it about 540 miles (870 km) southwest of Iwo To.  In-Fa was moving toward the northeast at 10 m.p.h. (16 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 994 mb.

A large upper level trough that extends south of Japan is producing strong southwesterly winds over the top of Tropical Storm In-Fa.  Those winds are causing strong vertical wind shear which is tilting the upper portion of the circulation of the tropical storm toward the northeast.  The stronger thunderstorms are all located northeast of the center of In-Fa.  It also appears drier air is wrapping around the southwestern part of the circulation.  The strong vertical wind shear will continue to weaken Tropical Storm In-Fa.  As it moves into a cooler environment In-Fa will gradually make a transition to an extratropical cyclone during the next 48 hours.

The upper level trough will continue to steer Tropical Storm In-Fa toward the northeast while it makes the transition to an extratropical cyclone.  On its anticipated track In-Fa could bring tropical storm force winds to Iwo To in 24 to 36 hours.