Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Typhoon Nock-ten Moves South of Manila

Typhoon Nock-ten moved across southern Luzon and weakened on Sunday.  At 10:00 p.m. EST on Sunday the center of Typhoon Nock-ten was located at latitude 13.8°N and longitude 120.9°E which put it near Batangas and about 75 miles (120 km/h) south-southeast of Manila, Philippines.  Nock-ten was moving toward the west at 18 m.p.h.  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 956 mb.

Typhoon Nock-ten weakened when the center moved over parts of southern Luzon.  Increased friction slowed the wind and areas of higher terrain temporarily disrupted the lower level circulation.  In addition easterly winds in the upper levels appeared to increase.  The increased vertical wind shear contributed to making the circulation more asymmetrical.  More of the thunderstorms formed in the western half of the circulation and there were fewer storms east of the center of circulation.

Typhoon Nock-ten will remain in a favorable environment for another day or so.  When Nock-ten moves west of Luzon into the South China Sea, it will move over water where the Sea Surface Temperature is near 29°C.  Typhoon Nock-ten could maintain its intensity or weaken slowly during the next 24 hours.  After that time Typhoon Nock-ten will move into an environment where the upper level winds are stronger.  Increased vertical wind shear will weaken the circulation.

A subtropical ridge to the north of Nock-ten is steering the typhoon toward the west and that general motion is expected to continue for another day or two.  The center of Typhoon Nock-ten passed near Catanduanes Island.  The center then moved near Tabaco, Ligao, Burias Island, San Francisco, and Marinduque Island.  The center is near Batangas.  It will move across Lake Taal and Lubang Island before it passes into the South China Sea.  Typhoon Nock-ten will continue to produce gusty winds and locally heavy rain as the center passes south of Manila.

Strong Typhoon Nock-ten Makes Landfall in Luzon

Strong Typhoon Nock-ten made landfall in Luzon on Sunday after passing very close to Catanduanes Island.  At 10:00 a.m. EST on Sunday the center of Typhoon Nock-ten was located at latitude 13.5°N and longitude 123.5°E which put it near Tabaco and about 215 miles (345 km) east-southeast of Manila, Philippines.  Nock-ten was moving toward the west at 12 m.p.h. (19 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. (290 km/h).  The minimum surface pressure was 924 mb.

The circulation of Typhoon Nock-ten is very well organized.  There is a circular eye with a diameter of 14 miles (23 km) at the center of circulation.  A ring of very strong thunderstorms surrounds the eye and the strongest winds are occurring in those thunderstorms.  A second ring of thunderstorms nearly surrounds the inner eye and eyewall.  Nock-ten may have a double eyewall structure.  Additional bands of thunderstorms are occurring outside the core of the circulation.  Winds to typhoon force extend out about 50 miles (80 km) from the center.  The core of Typhoon Nock-ten is generating strong upper level divergence which is pumping out mass in all directions.

The Hurricane Intensity Index (HII) is 31.6.  The Hurricane Size Index (HSI) is 15.5 and the Hurricane Wind Intensity Size Index (HWISI) is 47.1.  The indices indicate that Typhoon Nock-ten is capable of causing regional significant wind damage.

Typhoon Nock-ten will be moving through an atmospheric and oceanic environment that is supportive of tropical cyclones.  When the center of Typhoon Nock-ten is over water, it will move across areas where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  At times the center of Typhoon Nock-ten will move over portions of southern Luzon.  Nock-ten will weaken each time the center moves over land.  In addition, if an eyewall replacement cycle occurs, the strongest winds will slow as the inner eyewall decays.  However, the broader outer eyewall will cause Nock-ten to retain typhoon intensity for a longer period of time.

A subtropical ridge to the north of Nock-ten is steering the typhoon toward the west and that general motion is expected to continue.  On its anticipated track the center of Typhoon Nock-ten will pass near Naga, Calauag, Lucena, San Pablo,  and Manila in southern Luzon.

Typhoon Nock-ten is capable of doing significant wind damage.  Wind blowing water toward the coast will also create significant storm surges in east facing bays and inlets as the center of Nock-ten approaches.  When the center of circulation moves past parts of southern Luzon, the wind will shift to a southwesterly direction and there will be storms surges in in westerly facing bays and inlets.  Typhoon Nock-ten will produce very heavy rain over parts of southern Luzon.  Serious flooding and mudslides could occur in areas with steeper slopes.

Dangerous Typhoon Nock-ten Threatens the Philippines

Dangerous Typhoon Nock-ten intensified to super typhoon status on Saturday and it posed a significant threat to the northern Philippines.  At 10:00 a.m. EST on Saturday the center of Typhoon Nock-ten was located at latitude 13.5°N and longitude 127.1°E which put it about 440 miles (715 km) east of Manila, Philippines.  Nock-ten was moving toward the west at 8 m.p.h. (13 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. (290 km/h).  The minimum surface pressure was 928 mb.

Typhoon Nock-ten is a very strong, well organized typhoon.  Nock-ten has a small eye surrounded by a ring of strong thunderstorms.  A rainband is wrapping around the eye and concentric eyewalls could be forming.  Additional rainbands are rotating around the core of the circulation.  Winds to typhoon force extend out about 40 miles (65 km) from the center.  Thunderstorms in the core of the typhoon are generating strong upper level divergence which is pumping out mass in all directions.

Typhoon Nock-ten is moving through an environment that is favorable for tropical cyclones.  It is moving over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  If concentric eyewalls forms, then there could be a period of weakening as the inner eyewall dissipates and the inflow becomes concentrated in the outer eyewall.  Wind speeds could increase again if the outer eyewall starts to contract.  In either case Typhoon Nock-ten will be a dangerous typhoon when it reaches the Philippines

A subtropical ridge to the north of Nock-ten is steering the typhoon toward the west and that general motion is expected to continue.  On its anticipated track Typhoon Nock-ten will reach Catanduanes Island within 24 hours.  Nock-ten is expected to move across southern Luzon.

The Hurricane Intensity Index (HII) is 31.6 and the Hurricane Size Index (HSI) is 15.5.  The Hurricane Wind Intensity Size Index (HWISI) is 47.1.  Those indices indicate that Nock-ten is capable of producing regional significant wind damage.

Typhoon Nock-ten will cause significant wind damage when it moves across the Philippines.  It will also generate a significant storm surge in portions of the coast near the path of the center.  Nock-ten will cause heavy rain and create the potential for floods and mudslides over parts of Catanduanes Island and southern Luzon.

Typhoon Nock-ten Rapidly Intensifies Into Equivalent of a Major Hurricane

Typhoon Nock-ten intensified rapidly into the equivalent of a major hurricane on Friday.  At 10:00 p.m. EST on Friday the center of Typhoon Nock-ten was located at latitude 13.2°N and longitude 128.6°E which put it about 545 miles (880 km) east of Manila, Philippines.  Nock-ten was moving toward the west at 11 m.p.h. (18 km/h).  The maximum sustained wind speed was 125 m.p.h. (205 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 935 mb.

Nock-ten is a very well organized typhoon.  There is an eye with a diameter of 14 miles (23 km) at the center of Typhoon Nock-ten.  The eye is surrounded by a ring of strong thunderstorms.  Additional bands of thunderstorms surround the core of the circulation.  Winds to typhoon force extend out about 40 miles (65 km) from the center.  Thunderstorms around the center are generating strong upper level divergence in all directions.  The divergence is pumping out large amounts of mass which allowed the surface pressure to decrease rapidly.

The Hurricane Intensity Index (HII) is 23.6 and the Hurricane Size Index (HSI) is 15.5.  The Hurricane Wind Intensity Size Index (HWISI) is 39.1.  Those indices indicate that Typhoon Nock-ten is capable of causing major regional wind damage.

Typhoon Nock-ten will continue to move through an environment that is very favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Nock-ten could intensify more during the next 24 hours and it could become a super typhoon before it reaches the Philippines.

A subtropical ridge to the north of Nock-ten is steering the typhoon toward the west and that general motion is expected to continue.  On its anticipated track Typhoon Nock-ten could be near Catanduanes Island within 36 hours.  Nock-ten is likely to pass across southern Luzon and the center could move close to Manila.  Typhoon Nock-ten will be capable of causing major wind damage.  It will also bring heavy rain and create the potential for floods and mudslides.

Tropical Storm Nock-ten Strengthens on Its Way to the Philippines

Tropical Storm Nock-ten strengthened as it moved closer to the Philippines on Thursday.  At 10:00 p.m. EST on Thursday the center of Tropical Storm Nock-ten was located at latitude 12.0°N and longitude 132.7°E which put it about 850 miles (1370 km) east-southeast of Manila, Philippines.  Nock-ten was moving toward the west-northwest at 22 m.p.h. (35 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 987 mb.

Even though Tropical Storm Nock-ten moved quickly on Thursday the circulation continued to organized.  A mid-level eye appeared to develop on microwave satellite imagery.  Additional rainbands developed outside the core of the tropical storm.  Thunderstorms around the core of Nock-ten generated strong upper level divergence that pumped out mass in all directions.

Tropical Storm Nock-ten is moving through an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  An upper level ridge to the east of Nock-ten is producing southeasterly winds that are blowing toward the top of the circulation.  However, Tropical Storm Nock-ten is moving fairly rapidly toward the west-northwest.  The rapid motion is reducing the effective vertical wind shear, and so the wind shear is not inhibiting intensification.  Tropical Storm Nock-ten will continue to strengthen and it should become a typhoon within 12 to 24 hours.

A subtropical ridge to the north of Nock-ten is steering the tropical storm toward the west-northwest.  That general motion is expected to continue for another 24 to 36 hours.  The subtropical ridge is expected to strengthen after that time and it will steer Nock-ten more toward the west.  On its anticipated track Nock-ten will approach southeast Luzon in about 48 hours.

Nock-ten is likely to be a strong typhoon when it reaches the Philippines.  It could be the equivalent of a major hurricane.  In addition to strong winds, Nock-ten will generate a storm surge  and produce locally heavy rains.  It will produce a risk of floods and mudslides.

Tropical Storm Nock-ten Forms Near Yap

Tropical Storm Nock-ten formed near Yap on Wednesday.  At 10:00 p.m. EST on Wednesday the center of Tropical Storm Nock-ten was located at latitude 9.1°N and longitude 138.4°E which put it about 85 miles (140 km) southeast of Yap.  Nock-ten was moving toward the northwest at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 993 mb.

A distinct center of circulation developed in an area of thunderstorms near Yap and the system was named Tropical Storm Nock-ten.  The circulation of Nock-ten is still organizing.  A small well defined center exists at the core of the circulation.  A band of thunderstorms is beginning to wrap around the center.  Several additional bands of thunderstorms formed in the northern part of the circulation.  Thunderstorms near the center are beginning to generate upper level divergence which is pumping mass out to the west of the center.

Tropical Storm Nock-ten will move through an environment that is moderately favorable for intensification.  Nock-ten will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge north of Nock-ten is producing southeasterly winds which are blowing across the top of the tropical storm.  Those winds are preventing upper level divergence to east of Nock-ten.  Those winds are also causing moderate vertical wind shear which is slowing the rate of intensification.  When Nock-ten moves a little farther west, the vertical wind shear is expected to diminish and faster intensification could occur.  Nock-ten could intensify into a typhoon during the next several days.

A subtropical ridge north of Nock-ten is steering the tropical storm toward the northwest.  That general motion is expected to continue for another day or two.  The ridge could strengthen during the weekend and it could turn Nock-ten more toward the west in a couple of days.  On its anticipate track Tropical Storm Nock-ten could approach the Philippines in three or four days.  Nock-ten could be a typhoon by the time it reaches the Philippines.

Tropical Storm Tokage Develops Over the Central Philippines

A distinct center of circulation developed within a cluster of thunderstorms over the central Philippines on Thursday and the Japan Meteorological Agency designated the system as Tropical Storm Tokage.  At 10:00 p.m. EST on Thursday the center of Tropical Storm Tokage was located at latitude 11.7°N and longitude 122.0°E which put it near the northwestern tip of Panay Island and about 235 miles (380 km) south-southeast of Manila, Philippines.  Tokage was moving toward the west-northwest at 13 m.p.h. (20 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 1000 mb.

The core of the circulation of Tropical Storm Tokage is still organizing.  An inner band of thunderstorms wraps around the western and southern sides of the center of circulation.  An outer rainband wraps around the northern side of the circulation from the northeastern to the southwestern quadrants.  Thunderstorms near the core of Tokage are generating upper level divergence which is pumping mass away to the west and north of the tropical storm.

Tropical Storm Tokage will be moving through an environment that is favorable for intensification.  Tokage will be moving over water where the Sea Surface Temperature is near 29°C.  An upper level ridge east of Tokage is producing southeasterly winds which are blowing against the tropical storm.  Although those winds are restricting upper level divergence on the southeast side of Tokage, the overall effect of the vertical wind shear is minor.  Tropical Storm Tokage is likely to intensify during the next day or two and it could reach typhoon intensity.

Tokage is moving around the southwestern portion of a subtropical ridge which is steering the tropical storm to the west-northwest.  That general motion is expected to continue for another 12 to 24 hours.   After that time Tropical Storm Tokage will reach the western end of the subtropical ridge and it will begin to move toward the north.  On its anticipated track Tropical Storm Tokage will pass near Mindoro Island and the Calamian Group during the next 12 hours.  It will bring gusty winds and heavy rain to those islands.  Tokage is likely to pass west of Luzon.

Tropical Storm Ma-On Forms East of the Northern Marianas

Tropical Depression 27W intensified into Tropical Storm Ma-On east of the Northern Marianas on Thursday.  At 10:00 a.m. EDT on Thursday the center of Tropical Storm Ma-On was located at latitude 17.7°N and longitude 153.7°E which put it about 405 miles (655 km) south-southeast of Minami Tori Shima.  Ma-On was moving toward the west at 15 m.p.h. (24 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 1003 mb.

More thunderstorms developed near the center of a system originally designated Tropical Depression 27W and the Japan Meteorological Agency named it Tropical Storm Ma-On on Thursday.  Although many of the thunderstorms are still developing east of the center of circulation, a few stronger thunderstorms are forming around the center.  The thunderstorms around the center are beginning to generate upper level divergence which is pumping out mass.  Some additional rainbands appear to be forming in the eastern half of the circulation.

Tropical Storm Ma-On is moving through an environment that is favorable for intensification.  Ma-On is moving over water where the Sea Surface Temperature is near 30°C.  Ma-On is moving under the western end of an upper level ridge.  The upper level winds in that part of the ridge are not too strong and the ridge may be enhancing upper level divergence.  Tropical Storm Ma-On could intensify during the next day or so.  When Ma-On gets farther west, it will approach an upper level trough moving off of Asia.  There are stronger southwesterly winds on the eastern side of the trough and the vertical wind shear will increase at that time.

Tropical Storm Ma-On is moving along the southwestern end of a subtropical high pressure system.  The subtropical high is expected to steer Ma-On in a general west-northwesterly direction during the next two or three days.  On its anticipated track Tropical Storm Ma-On could approach the northernmost Marianas in about 36 hours.  It could bring gusty winds and locally heavy rain.

Typhoon Meari Passing Northwest of the Marianas

Typhoon Meari moved northwest of the Marianas on Saturday.  At 11:00 p.m. EDT on Saturday the center of Typhoon Meari was located at latitude 20.2°N and longitude 143.2°E which put it about 240 miles (390 km) west-northwest of Agrihan.  Meari was moving toward the northeast 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. (205 km/h).  The minimum surface pressure was 963 mb.

Typhoon Meari strengthened on Saturday.  An eye appeared on visible satellite imagery.  The eyewall is thicker on the southwestern side and thinner on the northeastern side.  There are also more rainbands in the southwestern part of the circulation.  Winds to typhoon force extend out about 70 miles (110 km) from the center of circulation.  Thunderstorms around the core of Typhoon Meari are generating upper level divergence which is pumping out mass.

Typhoon Meari will be moving through a favorable environment for another 12 to 24 hours.  Meari is moving over water where the Sea Surface Temperature is near 30°C.  The typhoon is moving along the transition zone between an upper level trough to its west and an upper level ridge to its east.  There are southwesterly winds blowing across the western side of Typhoon Meari, but those winds are actually enhancing the upper level divergence.  Vertical wind shear will increase when the upper level trough moves closer to the typhoon and Meari will start to weaken early next week.

The upper level trough is steering Typhoon Meari toward the northeast and that general motion is expected to continue for the next several days.  On its anticipated track the center of Typhoon Meari will pass northwest of the northernmost Marianas.  Meari will pass southeast of Iwo To as it moves toward the northern Pacific.

Tropical Storm Meari Intensifies Into a Typhoon

A well organized core developed at the center of Tropical Storm Meari on Friday and it intensified into a typhoon.  At 5:00 p.m. EDT on Friday the center of Typhoon Meari was located at latitude 17.0°N and longitude 140.0°E which put it about 425 miles (685 km) west-northwest of Saipan.  Meari was moving toward the north-northeast at 10 m.p.h. (16 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 979 mb.

A strong center of circulation finally developed within a broader area of low pressure that contained Tropical Storm Meari.  An inner rainband wrapped around the center and an eye appeared on microwave satellite imagery.  The formation of a tight inner core allowed Meari to strengthen into a typhoon.  There are some rainbands east of the center of Typhoon Meari, but most of the stronger thunderstorms are occurring in bands south and west of the center.  Thunderstorms in the core of Typhoon Meari are now generating upper level divergence which is pumping out mass.  Typhoon Meari is now a well organized tropical cyclone.

Typhoon Meari is moving through an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  An upper level ridge is over Meari which is resulting in light winds in the upper levels and little vertical wind shear.  In fact the upper level ridge is enhancing the divergence generated by the typhoon.  Typhoon Meari should continue to strengthen during the next 24 hours.  Since a well formed core now exists at the center, a period of rapid intensification is quite possible.

Typhoon Meari is moving around the western end of a subtropical ridge which is steering it toward the north-northeast.  That general motion is expected to continue for another day or so.  When Typhoon Meari gets farther north, westerly winds from the middle latitudes will push it toward the northeast more quickly.  On its anticipated track, Typhoon Meari could be near the northernmost Marianas in about 36 hours.  Meari could be a strong typhoon at that time.  Although no warnings are currently in effect, people on Alamagan, Pagan and Agrihan need to monitor the movement of Typhoon Meari.