Monthly Archives: December 2016

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 Cyclone Yvette Turns Toward Western Australia

Tropical Cyclone Yvette turned toward western Australia on Friday.  At 1:00 p.m. EST on Friday the center of Tropical Cyclone Yvette was located near latitude 15.1°S and longitude 117.3°E which put it about 370 miles (600 km) north-northwest of Port Headland, Australia.  Yvette was moving toward the east-southeast at 8 m.p.h. (13 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 992 mb.

An upper level ridge located to the northeast of Yvette is generating strong northeasterly winds which are blowing across the top of the tropical cyclone.  Those winds are creating strong vertical wind shear and for a time the strong upper levels winds sheared the top off of the circulation.  The upper level winds weakened slightly and new thunderstorms developed near the center of Tropical Cyclone Yvette.  The circulation of Yvette is very asymmetrical.  Most of the new thunderstorms are forming west of the center of circulation, although a few storms recently formed east of the center.  The upper level winds are also preventing upper level divergence to the east of Yvette.

Tropical Cyclone Yvette will be moving through an environment that will be only marginally favorable for intensification.  Yvette will move over water where the Sea Surface Temperature is near 29°C.  So, there is enough energy in the upper ocean to support intensification.  However, the strong upper level winds and vertical wind shear will inhibit intensification.  It is possible that the shear could decrease when Yvette moves east and gets closer to the core of the upper level ridge.  If the shear decreases, then some intensification may occur before Yvette reaches western Australia.

A subtropical ridge is steering Tropical Cyclone Yvette toward the east-southeast and that general motion is expected to continue.  On its anticipated track Tropical Cyclone Yvette will reach the coast of Western Australia in about 36 hours.  Landfall will likely occur between Cape Leveque and De Grey.  The highest probability is for a landfall near Bidyadanga.  Tropical Cyclone Yvette will produce locally heavy rain near where the center makes landfall.  Heavy rain could create the potential for flash floods.

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 Cyclone Yvette Develops Northwest of Australia

The circulation of a tropical low northwest of Australia continued to organize on Wednesday and the Australian Bureau of Meteorology named the system Tropical Cyclone Yvette.  At 7:00 a.m. EST on Wednesday the center of Tropical Cyclone Yvette was located at latitude 14.2°N and longitude 114.2°E which put it about 515 miles (830 km) northwest of Port Headland, Australia.  Yvette was making a slow clockwise loop and it was basically stationary.  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 991 mb.

The circulation of Tropical Cyclone Yvette is asymmetrical.  It has a well developed low level circulation but most of the thunderstorms are developing southwest of the center.  An upper level ridge over Australia is generating northeasterly winds which are blowing across the top of the circulation.  The moderate vertical wind shear is probably the reason why most of the thunderstorms are southwest of the center of circulation.  The upper level winds are inhibiting divergence to the east of Yvette, but they are enhancing the divergence to the west of the tropical cyclone.

The environmental factors are marginally favorable for intensification.  Tropical Cyclone Yvette will be moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are forecast to weaken and the vertical wind shear could decrease during the next several day.  As a result, Tropical Cyclone Yvette could slowly strengthen.

Winds at the steering level are currently variable around Yvette and as a result the tropical cyclone has made several clockwise loops.  The upper level ridge over Australia is forecast to extend west and the ridge is expected to steer Tropical Cyclone Yvette toward Western Australia.  On its anticipated track Tropical Cyclone Yvette is expected to approach the coast of Western Australia in three or four days.

Tropical Cyclone Yvette could bring gusty winds and locally heavy rain when it makes landfall.  Yvette could also generate a storm surge near where the center makes landfall.

Tropical Cyclone Vardah Nears Somalia

Tropical Cyclone Vardah neared landfall in Somalia late on Sunday.  At 7:00 p.m. EST on Sunday the center of Tropical Cyclone Vardah was located at latitude 8.9°N and longitude 51.2°E which put it about 80 miles (130 km) east of Eyl, Somalia.  Vardah was moving toward the west at 17 m.p.h. (27 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 1005 mb.

Tropical Cyclone Vardah has a small but well organized circulation.  A couple of rainbands wrap tightly near the center of circulation.  The are several other thin bands of showers.  Thunderstorms near the center are generating upper level divergence.  There is a distinct low level circulation, but it only extends about 120 miles (195 km) from the center.

Tropical Cyclone Vardah is being steering a little south of due west by a subtropical ridge north of the cyclone.  That general motion is expected to continue and Vardah could make landfall on the coast of Somalia in about 12 hours.  Tropical Cyclone Vardah could bring gusty winds and locally heavy rain where the center moves into Somalia.

Tropical Cyclone Vardah Moves Closer to Somalia

Tropical Cyclone Vardah moved closer to Somalia on Saturday.  At 7:00 p.m. EST on Saturday  the center of Tropical Cyclone Vardah was located at latitude 9.3°N and longitude 56.9°E which put it about 465 miles (745 km) east of Eyl, Somalia.  Vardah was moving toward the west-southwest at 18 m.p.h. (28 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 1004 mb.

Tropical Cyclone Vardah has a small but well defined circulation.  Several rainbands wrap close to the center.  However, the rainbands are thin and thunderstorms are scattered along them.  It appears that the circulation is pulling in drier air from the surrounding environment.  The thunderstorms near the core of the circulation are generating some upper level divergence.

Environmental conditions around Tropical Cyclone Vardah contain both positive and negative factors.  Vardah is moving over water where the Sea Surface Temperature is near 27°C.  So, there is enough energy in the upper ocean to support intensification.  The winds in the upper levels are not very strong and there is little vertical wind shear.  Drier air seems to be the primary negative factor that is preventing intensification of Tropical Cyclone Vardah.  The drier air could prevent significant intensification of Vardah, but the low level circulation could be strong enough to persist for several more days.

A strong subtropical ridge north of Vardah is steering the tropical cyclone toward the west-southwest and that general motion is expected to continue for several more days.  On its anticipated track Tropical Storm Vardah could approach the coast of Somalia in a little over 24 hours.

Tropical Cyclone Vardah is small.  It could produce gusty winds when it reaches the coast.  Isolated areas could also receive locally heavy rain.