Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Typhoon Soudelor Heading for Taiwan

Typhoon Soudelor moved steadily closer to Taiwan on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Typhoon Soudelor was located at latitude 20.6°N and longitude 129.7°E which put it about 450 miles (725 km) south-southeast of Okinawa and about 730 miles (1170 km) east-southeast of Taipei, Taiwan.  Soudelor was moving toward the west-northwest at 14 m.p.h. (23 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 952 mb.

Typhoon Soudelor went through an eyewall replacement cycle that resulted in temporary weakening while the inner eye dissipated and the outer eyewall contracted.  Soudelor appears to have completed the cycle and the convection in the new eyewall is growing.  The typhoon is in a very favorable environment.  The Sea Surface Temperature is near 30°C.  Upper level winds are very light and there is almost no vertical wind shear.  The circulation is very symmetrical with multiple rainbands.  Upper level divergence is pumping out mass in all directions.  Soudelor is likely to re-intensify during the next two days.

A subtropical ridge is steering Soudelor toward the west-northwest and that general steering pattern is expected to continue for another two or three days.  On its anticipated track Soudelor would reach Taiwan in less than 48 hours.  It could be a large and powerful typhoon when it gets there.  It is likely to bring strong winds and heavy rain.  Soudelor will weaken as it crosses Taiwan and then it will make a second landfall in China.

Typhoon Soudelor Becomes Equivalent of a Category 5 Hurricane

Typhoon Soudelor continued to intensify rapidly on Monday and it reached the equivalent of a Category 5 Hurricane on the Saffir-Simpson Scale.  At 5:00 p.m. EDT on Monday the center of Typhoon Soudelor was located at latitude 18.0°N and longitude 140.1°E which put it about 1020 miles (1640 km) east-southeast of Okinawa.  Soudelor was moving toward the west-northwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 175 m.p.h. (280 km/h) and there were wind gusts to 215 m.p.h. (350 km/h).  The minimum surface pressure was 907 mb.  The Hurricane Intensity Index (HII) for Soudelor was 40.4, the Hurricane Size Index was 13.6 and the Hurricane Wind Intensity Size Index was 54.0.  These indices mean that Soudelor is capable of producing regional catastrophic damage.

The upper level winds around Soudelor are very light and there is almost no vertical wind shear.  The typhoon has strong upper level divergence in all directions which is pumping out mass and causing the surface pressure to decrease rapidly.  It is over water where the Sea Surface Temperature is near 31°C and the circulation is extracting plenty of energy from the upper ocean.  The environment would support further intensification, but Soudelor is already a very powerful typhoon.  Soudelor rapidly completed an eyewall replacement cycle earlier today and future cycles could produce fluctuations in intensity.  Soudelor could remain a very intense typhoon for several more days.

A strong subtropical ridge is steering Typhoon Soudelor toward the west-northwest and that general steering pattern is expected to continue for the next few days.  On its anticipated track Soudelor could be near the southernmost islands of Japan in three days, near northern Taiwan in four days and near the coast of China in less than five days.  Although it is likely to weaken before it reaches any of those locations, it could still be a powerful typhoon at that time.

Typhoon Soudelor Intensifies Rapidly and Moves Over Saipan

Typhoon Soudelor intensified rapidly during the 12 hours before it moved directly over Saipan.  At 11:00 a.m. EDT on Sunday the center of Typhoon Soudelor was located at latitude 15.3°N and longitude 145.3°E which put it about 25 miles (40 km) west-northwest of Saipan.  It was moving toward the west-northwest at 11 m.p.h. (18 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 956 mb.  The airport on Saipan measured sustained wind to 54 m.p.h. (87 km/h) and wind gusts to 91 m.p.h. (147 km/h).  However, there were several observations when no wind speed was reported.  The minimum surface pressure reported was 958 mb.

Typhoon Soudelor organized quickly after the primary band wrapped completely around the center of circulation.  A tiny (4 mile wide) pinhole eye developed at the center of circulation and there are multiple bands of thunderstorms rotating around the center.   Soudelor is over warm Sea Surface Temperatures and there is little vertical wind shear.  Further intensification is likely and Soudelor could reach Super Typhoon status.

A subtropical ridge is steering Soudelor toward the west-northwest and that general motion is expected to continue for the next few days.  On its anticipated track Soudelor could approach the southernmost islands of Japan or Taiwan in four or five days.

Soudelor Almost a Typhoon as It Nears the Marianas

Tropical Storm Soudelor intensified on Saturday and it has almost reached typhoon status.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Soudelor was located at latitude 14.8°N and longitude 147.7°E which put it about 170 miles (275 km) east-southeast of Saipan.  Soudelor was moving toward the west-northwest at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 70 m.p.h. (115 km/h) and there were gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 978 mb.  A Typhoon Warning has been issued for Saipan and Tinian.  A Tropical Storm Warning has been issued for Rota.  A Typhoon Watch has been issued for Agrihan, Pagan and Alamagan.

The structure of Tropical Storm Soudelor improved on Saturday.  A long spiral band wrapped almost entirely around the center of circulation and numerous other spiral bands were apparent on satellite imagery.  There are more thunderstorms on the western side of the circulation.  Soudelor is moving over water where the Sea Surface Temperature is near 30°C.  An upper level ridge north of the tropical storm is causing light easterly winds over the circulation.  However, the vertical wind shear is modest and upper level divergence is increasing.  Soudelor is in a favorable environment.  Further intensification is likely and rapid intensification is possible.  Soudelor will very likely be a typhoon when it moves through Marianas.

A subtropical ridge is steering Soudelor toward the west-northwest and that pattern is expected to continue during the next few days.  On its anticipated track Soudelor will be near Saipan and Tinian in about 12 hours.  It could bring strong winds to those locations and other nearby islands.

Typhoon Halola Nearing Ryukyu Islands

Typhoon Halola turned northwestward on Friday and it is nearing the Ryukyu Islands.  At 5:00 p.m. EDT on Friday the center of Typhoon Halola was located at latitude 25.8°N and longitude 130.2°E which put it about 185 miles (300 km) east-southeast of Okinawa and about 50 miles (80 km) west-southwest of Minamidiato Island.  Halola was moving toward the northwest at 7 m.p.h. (11 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.

Halala weakened on Friday, but it was still a typhoon at the time of this post.  It has a well defined low level circulation, but there are fewer thunderstorms in northwestern portion of Halola.  It appears as if some drier air is moving into the northwestern side of the typhoon.  Upper level winds from the northeast are creating some vertical wind shear, but Halola has well developed upper level divergence to the south of the center.  Halola will move over water where the Sea Surface Temperature (SST) is near 28°C as it passes just north of Okinawa and it could stay at typhoon intensity for another 12 to 24 hours.  After that time it will move over cooler SSTs and the upper level winds will increase.  Halola is likely to weaken to a tropical storm over the weekend.

Typhoon Halola is moving around the western end of a subtropical ridge, which is why it has turned toward the northwest.  It will turn northward on Saturday and then turn northeastward in about 36 hours as strong upper level winds from the southwest begin to push it in that direction.  On its anticipated track the center of Typhoon Halola could pass between Okinawa and Amami in to 18 hours.  It is likely to bring wind and heavy rain to some of the Ryukyu Islands.  The center of Halola could be near or just west of Kyushu in about 36 hours.

Typhoon Halola Heading Toward Okinawa

Typhoon Halola moved steadily toward the west-northwest on Wednesday and it moved to within 550 miles of Okinawa.  At 11:00 p.m. EDT on Wednesday the center of Typhoon Halola was located at latitude 24.4°N and longitude 135.4°E which put it about 525 miles (850 km) east-southeast of Okinawa.  Halola was moving toward the west-northwest at 10 m.p.h. (16 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 956 mb.

The organization of Typhoon Halola improved on Wednesday.  There is an inner eye and a primary rainband may be wrapping around the center as well.  The circulation is more symmetrical and more thunderstorms formed on the western side of the typhoon.  There is well developed upper level divergence over the southeastern half of Halola.  Upper level winds from the northeast are inhibiting some of the upper level divergence over the northwestern part of Halola.  Since the typhoon is still over warm Sea Surface Temperatures (SSTs), it has the potential to intensify further during the next several days.  If the primary rainband wraps entirely around the circulation and creates concentric eyewalls, then an eyewall replacement cycle could cause fluctuations in intensity.

A subtropical ridge is steering Halola toward the west-northwest and that general motion is expected to continue for another two days.  After about 48 hours Halola will reach the western end of the ridge and turn toward the north.  Halola could threaten southwestern Japan or South Korea over the weekend.  On its anticipated track Halola will approach Okinawa in about 48 hours.  It could be a significant typhoon at that time and bring strong winds and heavy rain to the islands around Okinawa.

Halola Becomes a Typhoon South of Japan

A tropical cyclone named Halola intensified a few hundred miles south of Japan on Tuesday and it reached typhoon intensity.  At 5:00 p.m. EDT on Tuesday the center of Typhoon Halola was located at latitude 23.1°N and longitude 140.2°E which put it about 840 miles (1360 km) east-southeast of Okinawa.  Halola was moving toward the west at 11 m.p.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).  The minimum surface pressure was 967 mb.

Typhoon Halola is moving over water where the Sea Surface Temperature (SST) is near 28°C.  The circulation is relatively well organized and an eye has been visible intermittently on satellite imagery.  There are many more thunderstorms in the eastern half of the circulation and there have been breaks in the western side of the eyewall at times.  It could be that there is some drier air to the northwest of the center.  Halola is currently moving through a region where the upper level winds are relatively light and there has not been much vertical wind shear today.  The lack of wind shear has allowed upper level outflow to become well developed to the east and south of the center of circulation.  Halola has the potential to intensify further during the next 48 hours while it is a region of modest vertical wind shear.

A subtropical ridge is steering Halola toward the west and a general west-northwestward movement is expected to continue during the next several days.  In two or three days Halola will reach the western end of the subtropical ridge and it will turn toward the north.  Guidance from numerical models varies on the strength of the subtropical ridge and the timing of the northward turn.  It is possible that Halola could threaten southwestern Japan later this week.

Typhoon Nangka Making Landfall in Japan

Typhoon Nangka has reached the coast of Japan and it is making landfall.  At 11:00 a.m. EDT on Thursday the center of Typhoon Nangka was located at latitude 33.4°N and longitude 134.3°E which put it about 20 miles (35 km) southeast of Kochi, Japan.  Nangka was moving toward the north at 12 m.p.h. (19 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.

Nangka will bring strong winds and locally heavy rain to parts of Shikoku and Honshu during the next 24 hours.  It will weaken to tropical storm intensity as it moves across those islands.  Nangka is likely to emerge over the Sea of Japan on Friday.  It will be over cooler Sea Surface Temperatures at that time.  In addition, stronger westerly winds in the upper levels will create strong vertical wind shear.  Nangka will weaken further as those westerly winds turn it toward the east.

Typhoon Nangka Moving Toward Japan

Typhoon Nangka has moved steadily northward toward Japan during the past several days.  At 5:00 p.m. EDT on Tuesday the center of Typhoon Nangka was located at latitude 26.0°N and longitude 136.4°E which put it about 580 miles (935 km) south of Kobe, Japan.  Nangka was moving toward the north at 13 m.p.h. (21 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 956 mb.

Typhoon Nangka went through several eyewall replacement cycles in recent days which produced fluctuations in its intensity.  It currently has a circular, slightly ragged eye.  The circulation is still fairly symmetrical although the thunderstorms appear to be taller and stronger in the eastern half of the circulation.  There is strong upper level divergence to the east of the circulation.  Nangka remains over water where the Sea Surface Temperature (SST) is near 28°C.  There is little vertical wind shear and the typhoon has the potential for some intensification during the next 24 hours.

A subtropical ridge located east of Nangka is steering it toward the north and that general steering pattern is expected to continue during the next two days.  On its anticipated track Nangka could approach the island of Shikoku in about 48 hours.  The typhoon will move over cooler SSTs when it nears Japan, which will weaken it somewhat.  However, Nagka is a large powerful typhoon.  It has a Hurricane Intensity Index of 17.8 and a Hurricane Size Index of 26.7, which gives it a Hurricane Wind Intensity Size Index of 44.5.  At its current size and intensity Nanga is capable of producing widespread serious damage.

Typhoon Chan-hom Approaching Shanghai

Large Typhoon Chan-hom is moving northward toward Shanghai, China.  At 5:00 p.m. EDT on Friday the center of Typhoon Chan-hom was located at latitude 28.2°N and longitude 123.1°E which put it about 300 miles (500 km) south-southeast of Shanghai, China.  Chan-hom was moving to the northwest at 10 m.p.h. (16 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 956 mb.

Chan-hom still has a very symmetrical circulation, but the intensity of the thunderstorms appears to have weakened in recent hours.  The typhoon is moving over water where the Sea Surface Temperatures (SSTs) are cooler and that is the most likely cause for the decreased intensity of the thunderstorms.  As it nears the coast of China, more of the western half of the circulation will be over land and increased friction will further reduce the wind speeds.  Vertical wind shear may also increase as Chan-hom moves farther north.

Chan-hom is moving around the western end of the subtropical ridge which has been steering it toward the northwest.  As it moves around the end of the ridge, Chan-hom will first turn toward the north and then it could accelerate toward the northeast when it begins to be affected by the mid-latitude westerlies.  On its anticipated track the center of Chan-hom will be near Shanghai in about 24 hours.  Given the large size of Chan-hom, the typhoon could bring strong winds and locally heavy rain to the region near Shanghai.