Category Archives: Tropical Cyclones

Information about tropical cyclones

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.

Tropical Storm Felicia Forms Southwest of Baja California

A center of circulation finally developed in an area of thunderstorms southwest of Baja California and the system has been designated as Tropical Storm Felicia.  At 11:00 a.m. EDT on Thursday the center of Tropical Storm Felicia was located at latitude 19.1°N and longitude 114.9°W which put it about 415 miles (670 km) southwest of the southern tip of Baja California.  The maximum sustained wind speed was 40 m.p.h. (60 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1004 mb.

Felicia is not a particularly well organized tropical storm.  Most of the thunderstorms are forming in the southern half of the circulation and it does not have many spiral bands.  Recent satellite images seem to indicate that upper level divergence is beginning to occur.  Felicia is over water where the Sea Surface Temperature (SST) is near 27°C and the upper level winds do not appear to be too strong.  The potential for some intensification will exist for about another 24 hours.  In a day or so, Felicia will start to move over cooler SSTs and it will likely weaken by the weekend.

A subtropical ridge is steering Felicia toward the northwest and that general steering pattern is expected to continue as long as the vertical integrity of the circulation remains intact.  When Felicia moves over cooler SSTs, the height of the circulation will decrease and the storm will be steered by winds in the lower levels.  Those winds are expected to turn Felicia more toward the west in a day or two.  Felicia poses no threat to land at this time.

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.

Dolores Becomes a Major Hurricane

Hurricane Dolores intensified rapidly on Tuesday night and it has reached Major Hurricane status.  At 11:00 a.m. EDT on Wednesday the center of Hurricane Dolores was located at latitude 18.4°N and longitude 110.2°W which put it about 310 miles (500 km) south of Cabo San Lucas, Mexico.  The maximum sustained wind speed was 130 m.p.h. (215 km/h) which made Dolores a Category 3 hurricane on the Saffir-Simpson Scale.  There were wind gusts to 160 m.p.h. (260 km/h) and the minimum surface pressure was 946 mb.

Dolores is currently over water where the Sea Surface Temperature (SST) is around 29°C.  It is generating well developed upper level outflow which is pumping out mass and there is not much vertical wind shear.  Dolores could strengthen some more during the next 24 hours, although eyewall replacement cycles could produce fluctuations in intensity.  When Dolores moves north of latitude 20°N, it will move over cooler SSTs and it should start to weaken.  Given its size and intensity, it could take several days for the circulation around Dolores to spin down.

A ridge in the middle levels is steering Dolores toward the west-northwest.  That general steering pattern is expected to continue during the next few days and Dolores poses no current threat to land.

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.

Tropical Storm Claudette Forms Southeast of New England

An area of low pressure off the East Coast of the U.S. rapidly acquired tropical characteristics on Monday and it was classified as Tropical Storm Claudette by the National Hurricane Center.  At 1:00 p.m. EDT on Monday the center of Tropical Storm Claudette was located at latitude 37.4°N and longitude 68.1°W which put it about 290 miles (465 km) south-southeast of Nantucket Island, Massachusetts and about 550 miles (885 km) south-southwest of Halifax, Nova Scotia.  Claudette was moving toward the northeast at 15 m.p.h. (24 km/h).  The maximum sustained wind speed as 50 m.p.h. (85 km/h) and there were gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1004 mb.

Claudette began as a small low pressure system along a nearly stationary frontal boundary off the East Coast of the U.S.  Moderate wind shear kept the system looking non-tropical for much of the weekend.  The wind shear decreased on Monday morning and as the low moved over the warmer water of the Gulf Stream, thunderstorms developed near the center of circulation.  The stationary frontal boundary dissipated and the system took on a more tropical appearance.  Latent energy released in thunderstorms near the center produced the development of a warm core and some banding developed in the eastern portion of the circulation.  As a result of those changes, the system was classified as Tropical Storm Claudette.

Claudette could strengthen in the short term.  It is still over the Gulf Stream and the upper level winds are not too strong.  However, once the tropical storm moves north of latitude 40°N, it will move over cooler Sea Surface Temperatures.  In addition, stronger upper level winds will increase the vertical wind shear in a day or two.  Claudette could make a transition to an extratropical cyclone within 48 hours.

A combination of a trough approaching the eastern U.S, and a ridge over the Atlantic are expected to steer Claudette toward the northeast.  On its anticipated track, Claudette could approach eastern Nova Scotia in about 24 hours and Labrador in 30 hours.

Tropical Storm Dolores Forms South of Mexico

A low level circulation organized in a large area of thunderstorms south of Acapulco, Mexico on Sunday and the system was classified as Tropical Storm Dolores.  At 2:00 p.m. EDT on Sunday the center of Tropical Storm Dolores was located at latitude 15.6°N and longitude 102.1°W which put it about 145 miles (230 km) south-southwest of Zihuatanejo, Mexico and about 295 miles (475 km) southeast of Manzanillo, Mexico.  Dolores was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 55 m.p.h. (90 km/h).  The minimum surface pressure was 1002 mb.  The government of Mexico has issued a Tropical Storm Watch for the portion of the coast from Lazaro Cardenas to Cabo Corrientes.

The circulation around Dolores is not particularly well organized.  Most of the strong thunderstorms are occurring in the eastern half of the circulation.  There are few thunderstorms in the southwestern part of the tropical storm.  Upper level winds are light over Dolores and the tropical storm is producing strong upper level divergence which is pumping out mass.  Dolores is over water where the Sea Surface Temperatures are near 30°C and there is plenty of energy in the upper ocean to support intensification.  Dolores is close enough to Mexico that it could be pulling in some drier air from land, which may be inhibiting intensification at this time.  The environmental factors would support intensification and rapid intensification may be possible if Dolores moves farther away from the coast of Mexico.

A strong mid-level ridge over Texas and Mexico is steering Dolores toward the west-northwest.  That general steering pattern is expected to continue for the next few days.  On its anticipated track the center of Dolores is forecast to stay west of the coast of Mexico.  However, the proximity of Dolores to the coast prompted the issuance of a Tropical Storm Watch for a portion of the coast.

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.