Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Typhoon Goni Moving Closer to Northern Luzon and Taiwan

Typhoon Goni moved steadily westward on Wednesday and it got closer to northern Luzon and Taiwan.  At 11:00 p.m. EDT on Wednesday the center of Typhoon Goni was located at latitude 18.9°N and longitude 125.3°E which put it about 350 miles (565 km) southeast of Taipei, Taiwan.  Goni was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 937 mb.

Typhoon Goni intensified on Wednesday and it is a very well organized tropical cyclone.  It has a large well formed eye.  The circulation is symmetrical although there are more thunderstorms in the south half of the typhoon.  Upper level divergence is well developed and it is pumping out mass in all directions.  Goni remains over warm Sea Surface Temperatures and the upper level winds are relatively light.  Some further intensification is possible during the next day or so.  Goni could run into stronger upper level winds in two or three days which would create more vertical wind shear and start to weaken the typhoon.

A subtropical ridge has been steering Goni toward the west and it is expected to do so again on Thursday.  However, Goni is nearing the western end of the ridge and it is forecast to turn to the north on Friday.  Goni appears to have moved more slowly during the past few hours, which may be an indication that it is reaching the western end of the ridge.  An upper level trough northwest of Goni is expected to turn Goni toward the northeast during the weekend and then accelerate it toward western Japan.

On its anticipated track, the center of Goni is expected to pass northeast of Luzon.  However, the circulation is large enough that some of northern Luzon could experience strong winds and heavy rain.  The center of Goni is forecast to pass east of Taiwan, but it could also bring strong winds heavy rain to some locations there as well.  The core of Goni could pass very near Ishigaki Jima and bring very strong winds and heavy rain to the islands in that area.

Typhoon Atsani Reaches Equivalent of Cat. 5 Hurricane

Typhoon Atsani intensified over the past 24 hours and it is now the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.  At 8:00 a.m. EDT on Wednesday the center of Typhoon Atsani was located at latitude 19.6°N and longitude 151.3°E which put it about 1340 miles (2160 km) southeast of Tokyo, Japan.  Atsani was moving toward the northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 185 m.p.h. (300 km/h).  The minimum surface pressure was 918 mb.

Atsani is in an environment that is very favorable for tropical cyclones.  The Sea Surface Temperature (SST) is near 28°C.  The upper level winds are very light and there is almost no vertical wind shear.  Upper level divergence is pumping out mass in all directions and Atsani has a very circular appearance with a large eye evident on satellite imagery.  There are more rainbands and thunderstorms in the southern half of the circulation which is probably the result of warmer, moister air in area.

Atsani could maintain its current intensity for another 24 hours or so, although an eyewall replacement cycle will cause weakening if one occurs.  In another day or two the typhoon will start to move over cooler SSTs.  In addition as Atsani moves northward, it will start to be affected by the upper level westerlies in the middle latitudes.  Those winds will increase wind shear and weaken Atsani further.

Atsani is moving around the western end of a subtropical ridge which is steering it toward the northwest.  That general motion is expected to continue for another couple of days.  When Atsani reaches the western end of the ridge it will start moving toward the north.  Eventually, the upper level westerly winds will accelerate Atsani off to the northeast.  On its anticipated track Atsani would pass north of the Marianas and northeast of Iwo To.  At the current time the center of Atsani is forecast to pass about 100 miles east of ChiChi Jima.  However, a slight deviation of the track toward the west could bring Atsani closer to Chichi JIma and Iwo To.

 

Typhoon Goni Heading West

Typhoon Goni moved steadily westward away from the Mariana Islands on Monday.  At 11:00 p.m. EDT on Monday the center of Typhoon Goni was located at latitude 18.3°N and longitude 135.3°E which put it about 780 miles (1260 km) southeast of Okinawa.  Goni was moving toward the west at 19 m.p.h. (31 km/).  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 944 mb.

Goni appeared to go through an eyewall replacement cycle on Monday which resulted in a reduction in the maximum wind speed.  As the tiny pinhole inner eye weakened, the stronger winds were located in the larger outer eyewall.  The reduction in wind speed could be temporary, if the outer eye begins to contract.  Goni remains in a favorable environment.  It is moving over warm Sea Surface Temperature and the vertical wind shear is very modest.  The circulation is producing upper level divergence in all directions.  Goni will remain in a favorable environment for another two or three days and it should remain strong during that time period.

A subtropical ridge is steering Goni toward the west-northwest and that steering pattern is expect to continue for another 48 to 72 hours.  Later this week an upper level trough could approach the typhoon from the northwest.  Southwesterly winds on the eastern side of the trough could turn Goni toward the north later this week. On its anticipated track Goni could be near Taiwan, the northern Philippines or Okinawa when it makes that turn.

Typhoon Atsani Getting Bigger and Stronger

Typhoon Atsani continued to grow bigger and stronger on Monday.  At 11:00 p.m. EDT on Monday the center of Typhoon Atsani was located at latitude 16.3°N and longitude 155.8°E which put it about 1700 miles (2740 km) southeast of Tokyo, Japan.  Atsani was moving west-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 937 mb.

Typhoon Atsani has a very well organized circulation.  It is very symmetrical with a well formed eye and eyewall and it has multiple rainbands spiraling around the center of circulation.  Upper level divergence is pumping out mass in all directions, which is allowing the surface pressure to decrease.  There is little vertical wind shear and Atsani is moving over warm Sea Surface Temperatures.  Further intensification is likely, although eyewall replacement cycles could cause fluctuations in intensity.

A subtropical ridge is steering Atsani toward the northwest and that general steering pattern is expected to continue for the next few days.  On its anticipated track Atsani will pass north of the Marianas and it could be east of Iwo To in three or four days.

Goni Intensifies Rapidly Into a Strong Typhoon

Goni intensified rapidly from a tropical storm into a strong typhoon on Sunday.  At 11:00 p.m. EDT on Sunday the center of Typhoon Goni was located at latitude 16.7°N and longitude 141.1°E which put it about 265 miles (425 km) west of Anatahan.  Goni was moving toward the west-northwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 130 m.p.h. (215 km/h) which made Goni the equivalent of a major hurricane.  There were wind gusts to 160 m.p.h. (260 km/h) and the minimum surface pressure was 937 mb.

The circulation of Goni organized quickly on Sunday and it was able to intensify rapidly.  The primary rainband wrapped tightly around the center of circulation and a tiny pinhole eye formed in the center.  The band continued to wrap about the core of the circulation and it could be about to form a second, larger concentric eyewall.  The structure of Goni looks a lot like the circulation of Typhoon Soudelor did when it intensified rapidly.  Light easterly winds in the upper levels enhanced divergence to the west of Goni and pumped out mass allowing the pressure to fall rapidly.

Goni is moving over water where the Sea Surface Temperatures are warm.  The vertical wind shear is minimal and further intensification is possible.  If concentric eyewalls form, eyewall replacement cycles could produce fluctuations in intensity.

A subtropical ridge is steering Goni toward the west-northwest and that general steering pattern is expected to continue for another three or four days.  At that time Goni could be near the western end of the subtropical ridge.  An upper level trough in the mid-latitude westerlies could approach the typhoon from the northwest and turn it toward the north.

Tropical Storm Goni Brings Wind and Rain to the Marianas

Tropical Storm Goni brought wind and rain to the Northern Marianas on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Goni was located at latitude 15.1°N and longitude 144.4°E which put it about 60 miles (95 km) west of Tinian.  Goni was moving toward the northwest at 10 m.p.h. (16 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 982 mb.  A Tropical Storm Warning continues for Guam, Rota, Tinian, and Saipan and a Typhoon Watch continues for Saipan and Tinian.

The center of Tropical Storm Goni passed between Rota and Tinian on Saturday.  The tropical storm brought wind and rain to the northern Marianas.  The airport on Saipan reported a wind gust to 56 m.p.h. (90 km/h).  The stormy conditions could have setback the recovery from damage caused by Typhoon Soudelor.

The circulation around Goni continued to organize on Saturday.  A primary spiral band wrapped around the center of circulation and there have been indications that an eye may be forming in the center.  An upper level ridge east of Goni is causing some easterly winds over the circulation and is creating some vertical wind shear.  The shear is limiting thunderstorm activity on the eastern side of the circulation.  As Goni moves farther west, the wind shear will decrease.  It is moving over water where the Sea Surface Temperature is near 29°C.  The favorable environment will cause intensification and a period of rapid intensification is possible.

A subtropical ridge is steering Goni toward the west-northwest and that general steering pattern is expected to continue for the next few days.  Goni will move farther west of the Marianas on Sunday and conditions there should gradually improve.

Tropical Storm Goni Prompts Watches for Marianas

Tropical Storm Goni formed east of the Marianas on Friday and watches were issued for some of the islands because of the imminent threat it posed.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Goni was located at latitude 13.0°N and longitude 148.0°E which put it about 235 miles (370 km) southeast of Saipan.  Goni was moving toward the west-northwest at 10 m.p.h. (16 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.  A Typhoon Watch has been issued for Saipan and Tinian.  A Tropical Storm Watch has been issued for Guam and Rota.

The circulation of Tropical Storm Goni is still organizing.  Most of the thunderstorms are developing in the western half of the circulation.  An upper level ridge is generating easterly winds which are blowing across Goni and those winds are inhibiting the development of convection in the eastern part of the tropical storm.  Goni is moving over water where the Sea Surface Temperatures (SSTs) are near 29°C.  The environment supports intensification and Goni could intensify more rapidly in a day or two when the circulation is more well organized.  Goni could reach typhoon intensity within 48 hours.

A subtropical ridge is steering Goni toward the west-northwest and that general motion is expected to continue during the next few days.  On its anticipated track, the center of Goni could be very near Saipan in about 24 hours.  Goni could be a strong tropical storm on the verge of becoming a typhoon at that time.  Saipan is still recovering from the effects of Typhoon Soudelor.  Strong winds and heavy rain could set back those recovery efforts.

 

Typhoon Soudelor Making Landfall in China

Typhoon Soudelor crossed the Taiwan Strait and it is making landfall on the east coast of China near Quanzhou.  At 11:00 a.m. EDT on Saturday the center of Typhoon Soudelor was located at latitude 24.9°N and longitude 118.9°E which put it about 50 miles east of Quanzhou.  Soudelor was moving to the northwest at 10 m.p.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.

Soudelor weakened when it moved across Taiwan on Friday, but it was still a large typhoon when it made landfall in China.  Soudelor is expected to move toward the northwest while it moves farther inland over China.  Soudelor produced heavy rain when it moved over Taiwan and it could cause locally heavy rainfall over parts of eastern China before it dissipates.

Typhoon Soudelor Making Landfall in Taiwan

Powerful Typhoon Soudelor is making landfall on the east coast of Taiwan.  At 5:00 p.m. EDT on Friday the center of Typhoon Soudelor was located at latitude 23.8°N and longitude 122.1°E which put it about 125 miles (200 km) southeast of Taipei, Taiwan.  Soudelor was moving toward the northwest at 15 m.p.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 944 mb.

Soudelor is a large and powerful typhoon.  Winds to hurricane force extend out to 45 miles (70 km) from the center and tropical storm force winds extend out up to 250 miles (400 km) from the center.  Chiang Kai Shek airport reported winds to 53 m.p.h. (85 km/h) with gusts to 87 m.p.h. (140 km/h) when the center was still 125 miles away.  The Hurricane Intensity Index (HII) for Soudelor is 22.1, the Hurricane Size Index (HSI) is 17.7 and the Hurricane Wind Intensity Size Index (HWISI) is 39.8, which means that Soudelor is capable of causing regional major damage.  The HWISI for Soudelor is most similar to that for Hurricane Dennis when it hit the northwest Florida in 2005.  Soudelor is not quite as strong as Dennis was, but it is larger.  In addition to strong winds, heavy rain and the mountainous terrain of Taiwan create the potential for serious flooding.

Soudelor will weaken as it moves across Taiwan, but it could still be a typhoon when it emerges over the Taiwan Strait.  On its anticipated track, Typhoon Soudelor could make a second landfall near Fuzhou, China in 12 to 18 hours.  It could also bring strong winds and heavy rains to part of eastern China.

Strong Typhoon Soudelor Approaching Taiwan

Typhoon Soudelor continued to move steadily toward Taiwan on Thursday.  At 11:00 p.m. EDT on Thursday the center of Typhoon Soudelor was located at latitude 22.1°N and longitude 125.2°E which put it about 340 miles (550 km) south-southwest of Okinawa and about 420 miles (670 km) east-southeast of Taipei, Taiwan.  Soudelor was moving toward the west-northwest at 12 m.p.h. (19 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 944 mb.

Soudelor is a large symmetrical typhoon with multiple rainbands.  It has well-developed upper level divergence.  Soudelor completed an eyewall replacement cycle and it is now intensifying again.  The typhoon is moving over water where the Sea Surface Temperature is near 29°C and there is little vertical wind shear.  It is in a favorable environment and further intensification is possible before it makes landfall in Taiwan.  Soudelor will weaken while it moves across Taiwan.

A subtropical ridge is steering Soudelor toward the west-northwest and that general motion is expected to continue for another day or two.  On its anticipated track Soudelor will make landfall in Taiwan within 24 hours.  It will bring strong winds and heavy rainfall to Taiwan.  Soudelor has the potential to be a destructive typhoon.