Category Archives: Tropical Cyclones

Information about tropical cyclones

Typhoon Dujan Making Landfall in China

Typhoon Dujuan moved across Taiwan on Monday and it is currently making another landfall on the east coast of China.  At 11:00 p.m. EDT the center of Typhoon Dujuan was located at latitude 25.3°N and longitude 118.6°E which put it near Putian, China.  Dujuan was moving toward the northwest at 13 m.p.h.  The maximum sustained wind speed was 85 m.p.h. (135 m.p.h.) and there were wind gusts to 105 m.p.h. (170 km/h).  The minimum surface pressure was 976 mb.

Dujuan brought strong winds and heavy rain when it moved across Taiwan.  It weakened as the center moved over the mountains on Taiwan, but its large size and intensity allow Dujuan to survive.  Dujuan was still a typhoon as it moved into the coast of eastern China near Putian.  It could produce heavy rainfall and flooding as it moves inland.  Dujuan should spin down gradually during the next few days as it moves farther into eastern China.

Recon Finds Marty a Hurricane, Mexico Issues Warnings

A reconnaissance plane investigated Marty on Monday afternoon and the data showed that Marty was a hurricane.  At 5:00 p.m. EDT on Monday the center of Hurricane Marty was located at latitude 16.7°N and longitude 102.1°W which put it about 75 miles (125 km) south-southwest of Zihuatanejo, Mexico.  Marty was moving toward the northeast at 6 m.p.h. (10 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. (155 km/h).  The minimum surface pressure was 986 mb.

The government of Mexico has issued a Hurricane Warning for the portion of the coast from Tecpan de Galeana to Lazaro Cardenas.  A Tropical Storm Warning has been issued for the coast from Tecpan de Galeana to Acapulco.  A Tropical Storm Watch has been issued for the portion of the coast from Lazaro Cardenas to Punta San Telmo.

Although an upper level trough over Mexico has been producing southwesterly flow and causing moderate vertical wind shear over Marty, the vertical integrity of the circulation has been maintained.  So, instead of blowing the top off the circulation, the southwesterly winds have pushed the entire circulation toward the northeast.  As Marty moved over water where the Sea Surface Temperature was near 30°C, it extracted enough energy from the water to intensify into a hurricane.  The southwesterly winds inhibited upper level divergence on the western side of the circulation, but the upper level divergence east of Marty pumped out mass and the pressure decreased.

The environment is not favorable for much more intensification.  The upper level trough is expected to continue to cause vertical wind shear.  In addition, Marty is close enough to the coast of Mexico that the hurricane will begin to pull in some drier air from land.  Marty could intensify a little more, but it is likely to weaken on Tuesday.  If Marty makes landfall, it will weaken quickly.

The upper level trough is pushing Marty northeastward toward the coast of Mexico.  Unless the shear blows the upper part of the circulation away from the lower portion, it will continue to move toward the coast.  Marty could make landfall in 12 to 24 hours, which is why the government of Mexico issued warnings for the coast.  Hurricane Marty could bring strong winds and locally heavy rainfall when it moves inland.

Large Dangerous Typhoon Dujuan Nearing Taiwan

Large and dangerous Typhoon Dujuan is nearing Taiwan.  At 11:00 p.m. EDT on Sunday the center of Typhoon Dujuan was located at latitude 23.5°N and longitude 123.2°W which put it about 185 miles (300 km) southeast of Taipei, Taiwan.  Dujuan was moving toward the west-northwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 912 mb.

Typhoon Dujuan is a very symmetrical storm with a large eye.  Winds to hurricane force extend out 60 miles from the center.  A weather station on Ishigaki Jima, Japan has reported winds over 54 m.p.h. (87 km/h) for the past five hours even though the center is passing south of that island.  The upper level winds around the typhoon are light and upper level divergence is pumping out mass in all directions  Typhoon Dujuan is likely to maintain its intensify until it makes landfall in Taiwan.  When the core of the typhoon moves over the mountains on Taiwan it will weaken.  However, given Dujuan’s size and intensity, it is likely to still be a typhoon when it moves west of Taiwan.

A subtropical ridge north of Dujuan is steering the typhoon toward the west-northwest and that general steering pattern is expected to continue.  On its anticipated track Dujuan will make landfall in northeastern Taiwan in less than 12 hours.  It will move across Taiwan and the center could reform northwest of that island.  Dujuan could make a landfall in China between Xiamen and Fuzhou in less than 24 hours.

Dujuan has the potential to be a very destructive typhoon.  It has a Hurricane Intensity Index of 29.9 and a Hurricane Size Index of 21.3.  Those numbers produce a Hurricane Wind Intensity Size Index of 51.2.  Those Indices suggest it is capable of producing widespread significant damage.  In addition to wind damage, Dujuan is capable of producing very heavy rainfall and floods.

Marty Intensifies and Mexico Issues a Tropical Storm Watch

Tropical Storm Marty intensified on Sunday and the government of Mexico issued a Tropical Storm Watch for a portion of the west coast.  At 2:00 p.m. EDT on Sunday the center of Tropical Storm Marty was located at latitude 15.0°N and longitude 102.8°W which put it about 235 miles (380 km) southwest of Acapulco, Mexico.  Marty was moving toward the north-northeast at 6 m.p.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 997 mb.  A Tropical Storm Watch has been issued for the portion of the coast from Acapulco to Lazaro Cardenas, Mexico.

The structure of Tropical Storm Marty improved on Sunday morning.  A long rainband stretched around the southern and eastern sides of the circulation and more thunderstorms developed near the center or circulation.  Marty is over water where the Sea Surface Temperature (SST) is near 30°C, which means there is a lot of energy in the upper ocean.  However, an upper level trough extends from the western Gulf of Mexico across northern Mexico.  The upper level trough is causing westerly winds, which could already be producing vertical wind shear over the northern half of the circulation of Tropical Storm Marty.  Very warm SSTs mean that the potential for intensification exists, but the vertical wind shear will limit how much intensification actually occurs.  If the upper level winds get stronger, they could shear the top half of the circulation away from the bottom half and cause Marty to dissipate.

The upper level trough is beginning to steer Marty toward the north-northeast and the tropical storm is likely to move in that direction over the short term.  The ultimate track of Marty will be determined by the vertical integrity of the circulation and the strength of the vertical wind shear.  If the wind shear is not too strong and the upper and lower portions of the circulation remain together, then the trough will steer all of Marty toward the northeast.  In that case it could make landfall on the Mexican coast in several days.  However, if the vertical wind shear blows then top off of the circulation, then the upper level portion will move northeast toward Mexico, while the lower part of the tropical storm is left behind.  The upper half of the circulation could still bring heavy rain and the potential for floods to parts of Mexico, even if the surface circulation does not make landfall.

Shear Hits Tropical Storm Niala and It Turns West

After intensifying earlier on Saturday, vertical wind shear began to affect Tropical Storm Niala and it turned westward.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Niala was located near latitude 16.9°N and longitude 152.8°W which put it about 245 miles (395 km) southeast of Hilo, Hawaii.  Niala was moving toward the west at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 992 mb.  A Tropical Storm Watch remains in effect for Hawaii County.

A large upper level trough centered northeast of Hawaii is causing southwesterly winds that are blowing over Tropical Storm Niala.  The wind shear is blowing the tops off the thunderstorms that try to form near the center of circulation.  As a result the low level circulation is exposed on satellite imagery.  The effect of the wind shear will be to weaken Niala even though it is over warm Sea Surface Temperatures.

Since there are not tall thunderstorms near the center of circulation, it is being steered toward the west by winds lower in the atmosphere.  A general westerly motion is expected for the next several days and Tropical Storm Niala is likely to pass south of Hawaii.

Powerful Typhoon Dujuan Heads Toward Taiwan

Powerful Typhoon Dujuan turned west on Saturday and headed for Taiwan.  At 11:00 p.m. EDT on Saturday the center of Typhoon Dujuan was located at latitude 22.3°N and longitude 127.0°E which put it about 380 miles (610 km) east-southeast of Taipei, Taiwan and about 300 miles (480 km) south of Okinawa.  Dujuan was moving toward the west at 9 m.p.h. (15 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 925 mb.

Dujuan continued to intensify on Saturday and it is a powerful well organized typhoon.  Dujuan has a large symmetrical eye which is surrounded by strong thunderstorms.  Upper level divergence is pumping out mass and the surface pressure is decreasing.  Dujuan is over warm Sea Surface Temperatures and there is not much vertical wind shear.  Further intensification is possible, although if concentric eyewalls form, it could disrupt the intensification trend.

An upper level ridge north of Dujuan steered the typhoon a little north of due west on Saturday.  That general motion is expected to continue for another day or two.  On its anticipated track Dujuan will pass near the southwestern Ryukyu Islands in about 24 hours.  It will approach Taiwan in about 30 hours and it could reach China in less than two days.  Dujuan is a large powerful typhoon and it will bring strong winds and heavy rain.  It could produce flooding in parts of Taiwan and eastern China.

Niala Prompts Tropical Storm Watch for Hawaii

Tropical Storm Niala organized quickly southeast of Hawaii on Friday and the Central Pacific Hurricane Center issued a Tropical Storm Watch for Hawaii County.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Niala was located at latitude 15.7°N and longitude 150.4°W which put it about 415 miles (665 km) southeast of Hilo, Hawaii.  Niala was moving toward the northwest at 7 m.p.h. (11km/h).   The maximum sustained wind speed was 45 m.p.h. (70 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1001 mb.

The circulation inside Niala consolidated quickly around the core of the tropical storm on Friday.  A primary rainband wrapped around the eastern and northern side of the circulation creating a small eyelike feature at the center of circulation.  At least three additional rainbands formed in the eastern half of the tropical storm.  There are fewer thunderstorms in the western half of the circulation which could indicated the presence of drier, more stable air in that part of Niala.

Niala is over water where the Sea Surface Temperatures are nearly 29°C.  The upper level winds are not too strong and the thunderstorms around the core of the circulation are generating upper level divergence,  Niala could strenthen during the next day or so.  A large upper level trough extends from northeast of Hawaii to the islands.  As Niala moves toward the northwest, it will start to move under strong southwesterly winds on the eastern side of the trough.  Those winds will create strong vertical wind shear and Niala will weaken as it approaches Hawaii.

A subtropical ridge is steering Niala toward the northwest and that general motion is expected to continue for another 24 hours.  When the wind shear weakens Niala, the circulation will not extend as high into the atmosphere.  After that time the winds lower in the atmosphere will steer the weakening Niala toward the west.

Dujuan Reaches Typhoon Intensity South of Okinawa

Tropical Storm Dujuan continued to strengthen on Thursday and it reached typhoon intensity.  At 11:00 p.m. EDT on Thursday the center of Typhoon Dujuan was located at latitude 19.4°N and longitude 132.1°E which put it about 575 miles (930 km) south-southeast of Okinawa.  Dujuan was moving toward the north-northwest at 4 m.p.h. (6 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 980 mb.

The circulation around Typhoon Dujuan is becoming increasingly well organized.  A spiral band wrapped entirely around the center of circulation creating a large eye in the middle of the typhoon.  Additional spiral bands are forming, especially in the southern half of the circulation.  Thunderstorms in the eyewall are generating upper level divergence which is increasing with time.  Recent satellite images suggest that they eye may be contracting which would be another sign of intensification.

Dujuan is in an environment that favors intensification.  The Sea Surface Temperatures are warm and the speed of the upper level winds is decreasing.  An upper level ridge west of Dujuan is producing some northerly winds over the top of the typhoon, but the vertical wind shear is decreasing.  Intensification is likely and a period of rapid intensification is possible.  Dujuan could become the equivalent of a major hurricane in 24 to 48 hours.

Typhoon Dujuan is between a subtropical ridge to its northeast and another ridge to its northwest.  As a result, it moved slowly toward the northwest on Thursday.  Dujuan is expected to continue to move in a general northwesterly direction for another day or two.  The ridge west of Dujuan is expected to extend north of the typhoon during the weekend.  When the ridge extends north of Dujuan, it will steer the typhoon more toward the west.

On its anticipated track Typhoon Dujuan could approach the southwestern Ryukyu Islands including Ishigaki JIma in 60 to 72 hours.  Dujuan could be near Taiwan in about three and a half days and it could reach the coast of China in less than five days.  Dujuan could be a large and powerful typhoon capable of bringing strong winds and heavy rain by the time it reaches those areas.

Tropical Storm Dujuan Intensifying Southeast of Okinawa

After several days where vertical wind shear pushed most of the thunderstorms west of the core of the circulation, Tropical Storm Dujuan began to intensify on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Dujuan was located at latitude 18.9°N and longitude 132.7°E which put it about 620 miles (1000 km) southeast of Okinawa.  Dujuan was moving toward the west-northwest 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 988 mb.

The circulation near the core of Tropical Storm Dujuan is showing more organization.  Thunderstorms are developing closer to the center of circulation, although most of the stronger storms are still south and southwest of the center.  The distribution of thunderstorms is an indication that an upper level ridge west of Dujuan is still generating northeasterly winds over the top of the tropical storm.  Some of the storms closer to the center of circulation are starting to generate upper level divergence.

Dujuan is over water where the Sea Surface Temperatures are near 30°C.  Intensification is likely but vertical wind shear could limit the rate of intensification in the short term.  The wind shear is likely to decrease in a day or two as Dujuan moves into an area where the upper level winds are lighter.  Dujuan could become a typhoon within 24 to 36 hours and it could reach the equivalent of a major hurricane during the weekend.

Tropical Storm Dujuan is being steered toward the west-northwest by a subtropical ridge located to its northeast,  That general steering patter is expected to continue for another 24 to 36 hours.  At that time Dujuan will be between the ridge to its east and another upper level ridge to its west, and it could turn toward the northwest for a day or so.  The western ridge is expected to build north of Dujuan and turn it more toward the west in three or four days.  On its anticipated track Dujuan could approach the southern islands of Japan in three or four days.  It could be near Taiwan in five days.  Dujuan could be a strong typhoon by that time.

Tropical Depression 16E Could Bring Heavy Rain to Southwest U.S.

A center of circulation organized within a cluster of thunderstorms west of Baja California on Sunday and the system was designated Tropical Depression Sixteen-E.  At 5:00 p.m. EDT on Sunday the center of Tropical Depression Sixteen-E (TD16E) was located at latitude 25.0°N and longitude 113.7°W which put it about 90 miles (145 km) west of Cabo San Lazaro, Mexico.  TD16E was moving toward the north-northwest at 14 m.p.h. (22 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. (70 km/h).  The minimum surface pressure was 1003 mb.

Tropical Depression 16E has only a few hours before it will move over the central part of Baja California.  Although it is over water where the Sea Surface Temperature is near 27°C little, if any, intensification is expected.  When TD16E crosses Baja California, the terrain and increased vertical wind shear are likely to blow the upper portion of the circulation northward faster than the lower portion of the circulation.  The high clouds could reach parts of the southwestern U.S. within 24 hours.  Moving over mountains will disrupt the lower part of the circulation, but the rotation in the middle levels could persist for several days as it moves northward.

An upper level ridge centered over Texas and an upper level low west of Baja California are combining to steer TD16E northward and that general motion should continue for the next several days.  On its anticipated track TD16E could reach the coast of Baja California near Punta Abreojos in about 12 hours.  It could then move across Baja and the Gulf of California and make a second landfall on the coast west of Hermosillo on Monday morning.  TD16E or its remnants could be approaching southern Arizona later on Monday.  Convection and a flow of moisture associated with TD16E could produce locally heavy rainfall when it is forced to rise of mountains.  It could cause flooding in parts of Baja California, northwestern Mexico and the southwestern U.S.