Tag Archives: 01W

Vongfong Rapidly Intensifies Into a Typhoon East of Samar

Former Tropical Storm Vongfong rapidly intensified into a typhoon east of Samar on Wednesday.  At 11:00 a.m. EST on Wednesday the center of Typhoon Vongfong was located at latitude 12.3°N and longitude 127.6°E which put it about 140 miles (225 km) east of Dolores, Philippines.  Vongfong was moving toward the west-northwest at 7 m.p.h. (11 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 966 mb.

Typhoon Vongfong rapidly intensified on Wednesday from a strong tropical storm into a typhoon.  A small circular eye formed at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Vongfong.  Storms near the core were generating strong upper level divergence which was pumping mass away from the typhoon in all directions.  The removal of mass was allowing the surface pressure to decrease quickly, which caused the rapid intensification.

The circulation around Typhoon Vongfong was small.  Winds to typhoon force extended out 20 miles (30 km) from the center of circulation.  Winds to tropical storm force extended out 90 miles (145 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Vongfong was 17.8.  The Hurricane Size Index (HSI) was 6.4 and the Hurricane Wind intensity Size Index (HWISI) was 24.2.  Typhoon Vongfong was capable of causing localized serious damage.

Typhoon Vongfong will move through an environment favorable for intensification during the next 24 hours.  Vongfong will move over water where the Sea Surface Temperature is near 29.5°C.  It will move under a small upper level ridge east of the Philippines.  The upper level winds in the ridge are weak and there will be little vertical wind shear.  Typhoon Vongfong will continue to intensify rapidly in the short term.  Vongfong is likely to strengthen into the equivalent of a major hurricane during the next 6 to 12 hours.

Typhoon Vongfong will move around the western end of a high pressure system centered southeast of Japan.  The high will steer Vongfong toward the west-northwest during the next 24 hours.  Typhoon Vongfong will start to move more toward the north-northwest in a day or so, when it nears the western end of the high pressure system.  On its anticipated track the core of Typhoon Vongfong could approach northern Samar in about 18 hours.  Vongfong could approach Catanduanes Island and southeastern Luzon in about 24 hours.  Outer bands on the western side of Typhoon Vongfong could start to drop heavy rain over parts of Samar during the next 12 to 18 hours.

Tropical Storm Vongfong Develops East of the Philippines

Tropical Storm Vongfong developed east of the Philippines on Tuesday.  At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Vongfong was located at latitude 11.6°N and longitude 128.7°E which put it about 165 miles (270 km) east of Samar, Philippines.  Vongfong was moving toward the north-northwest at 7 m.p.h. (11 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 1002 mb.

Former Tropical Depression 01W strengthened on Tuesday and the Japan Meteorological Agency designated the low pressure system as Tropical Storm Vongfong.  The circulation around Vongfong was still organizing.  More thunderstorms were developing near the center of circulation.  Other thunderstorms were occurring in a primary rainband in the eastern side of Tropical Storm Vongfong.  Bands in the northern and western parts of the circulation consisted primarily of showers and lower clouds.  Storms near the center of circulation were generating upper level divergence which was pumping mass away from the tropical storm.  Winds to tropical storm force extended out 75 miles (120 km) from the center.

Tropical Storm Vongfong will move through an environment favorable for intensification during the next 36 hours.  Vongfong will move over water where the Sea Surface Temperature is near 29°C.  It will move under a small upper level ridge centered east of the Philippines.  The winds in upper ridge are weak and there will be little vertical wind shear.  Tropical Storm Vongfong will continue to intensify and it could strengthen to a typhoon within 24 to 36 hours.  A period of rapid intensification could occur after the inner part of the circulation becomes more organized.

Tropical Storm Vongfong will move around the western end of a high pressure system centered south of Japan.  The high pressure system is forecast to strengthen during the next 36 hours and it will steer Vongfong more toward the west-northwest on Wednesday.  On its anticipated track Tropical Storm Vongfong could approach northern Samar and southeastern Luzon in 36 to 48 hours.  Vongfong could be a typhoon at that time.  It could also drop locally heavy rain and cause flash floods over northeastern parts of the Philippines.

Tropical Depression Forms East of Philippines

A tropical depression formed east of the Philippines on Monday.  At 11:00 a.m. EDT on Monday the center of the tropical depression was located at latitude 8.6°N and longitude 129.0°E which put it about 165 miles (270 km) east of Mindanao.  It was moving toward the northwest at 5 m.p.h. (8 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. (75 km/h).  The minimum surface pressure was 1006 mb.

The circulation around a low pressure system east of the Philippines exhibited greater organization on Monday and the Japan Meteorological Agency classified the system as a tropical depression.  More thunderstorms formed near the center of the depression.  The strongest thunderstorms were east of the center of circulation.  Bands of showers and thunderstorms were occurring in the eastern and southern parts of the circulation.  Bands in the northern and western sides of the depression consisted mostly of showers and lower clouds.  Storms near the center of circulation began to generate upper level divergence which was pumping mass away from the tropical depression.

The tropical depression will move through an environment favorable for intensification during the next several days.  The depression will move over water where the Sea Surface Temperature is near 29°C.  It will move under a small upper level ridge that is between an upper trough west of the Philippines and another upper trough northeast of the Philippines.  The upper level winds are weaker in the small ridge and there will be less vertical wind shear.  The tropical depression is likely to intensify into a tropical storm during the next 24 hours and it could strengthen into a typhoon later this week.

The tropical depression will move around the western end of a high pressure system centered south of Japan.  The high will steer the depression slowly toward the northwest during the next few days.  On its anticipated track the depression could approach the northern Philippines later this week.  It could be a typhoon by the time it approaches the northern Philippines.

Tropical Storm Bolaven Forms Over the South China Sea

Tropical Storm Bolaven formed over the South China Sea near the Spratly Islands on Tuesday.  At 10:00 p.m. EDT on Tuesday the center of Tropical Storm Bolaven was located at latitude 10.4°N and longitude 115.1°E which put it about 620 miles (1000 km) east of Ho Chi Minh City, Vietnam.  Bolaven was moving toward the west-northwest at 21 m.p.h. (33 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 1002 mb.

A low level center of circulation developed on the eastern side of a cluster of thunderstorms that moved across the southern Philippines on Monday.  The center exhibited greater organization on Tuesday and the Japan Meteorological Agency designated the system as Tropical Storm Bolaven.  The structure of Tropical Storm Bolaven is asymmetrical.  The strongest thunderstorms are occurring northwest of the center of circulation.  Thin bands of low clouds and showers were revolving around the center of circulation in the other quadrants of Tropical Storm Bolaven.

Tropical Storm Bolaven is moving around the southern side of an upper level ridge centered east of the Philippines.  The ridge is generating strong southeasterly winds which are blowing across the top of the circulation.  Those winds are causing moderate vertical wind shear.  The wind shear is probably the reason why most of the stronger storms are occurring northwest of the center of circulation.  Although Bolaven will move over water where the Sea Surface Temperature is near 28°C, the vertical wind shear will likely prevent intensification.  In fact if the shear increases, then Bolaven could weaken to a tropical depression.

The ridge north of Bolaven is steering the tropical storm toward the west-northwest and that general motion is expected to continue for several more days.  On its anticipated track Tropical Storm Bolaven could reach the coast of South Vietnam in 24 to 36 hours.  Bolaven will bring gusty winds and locally heavy rain to parts of southern Vietnam.

Tropical Depression 01W Redevelops East of Vietnam

More thunderstorms developed on Saturday around the circulation previously designated Tropical Depression 01W earlier this week when it moved through the southern Philippines.  At 10:00 p.m. EST the center of Tropical Depression 01W was located at latitude 9.4°N and longitude 109.1°E which put it about 220 miles (355 km) east-southeast of Ho Chi Minh City, Vietnam.  The depression was moving toward the west at 6 m.p.h. (10 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. (75 km/h).  The minimum surface pressure was 1002 mb.

After persisting mainly as a low level circulation during the past few days as it moved westward across the South China Sea, more thunderstorms developed in the depression on Saturday.  Most of the thunderstorms developed in bands north and west of the center of circulation.  There were bands of low clouds and showers in the southeastern portion of the circulation. The depression has a well defined low level center of circulation.  Thunderstorms were starting to generate some upper level divergence which was pumping mass away to the northwest of the depression.

The depression will be moving through an environment that is marginal for intensification.  It will be moving over water where the Sea Surface Temperature is near 26°C to 27°C.  So, there will be enough energy in the upper ocean to support intensification.  An upper level ridge to the east of the depression is generating southeasterly winds which are blowing across the top of the circulation.  The moderate vertical wind shear will inhibit intensification.  If the shear does not increase, the depression could maintain its intensity or strengthen slightly during the next 24 hours.

A ridge north of the depression is steering it toward the west and that general motion is expected to continue for another day or two.  On its anticipated track the depression will move toward the southernmost part of Vietnam.  The depression could bring locally heavy rain to southern Vietnam.  The rain could be heavy enough to cause flooding in some areas.

Tropical Depression 01W Forms Near Mindanao

A center of circulation formed within a cluster of thunderstorms east of Mindanao on Saturday and the system was designated Tropical Depression 01W.  At 10:00 p.m. EST on Saturday the center of Tropical Depression 01W was located at latitude 9.2°N and longitude 126.5°E which put it about 200 miles (320 km) east-southeast of Cebu, Philippines.  The depression was moving toward the northwest at 10 m.p.h.  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1000 mb.

Although there is a distinct center of circulation in Tropical Depression 01W, the distribution of thunderstorms is asymmetrical.  Most of the stronger thunderstorms are forming in the northern half of the circulation and there are few thunderstorms in the southern half of the circulation.  The thunderstorms in the northern half of the circulation are generating upper level divergence that is pumping out mass toward the northeast and northwest of the tropical depression.

Tropical Depression 01W will be moving through an oceanic and atmospheric environment that is somewhat favorable for intensification.  It will move over water where the Sea Surface Temperature is near 28°C.  An upper level ridge is generating southeasterly winds which are blowing across the top of the depression, but the vertical wind shear is not too strong.  However, the center of Tropical Depression 01W will move over some of the islands of the southern Philippines.  Increases friction and high topography will disrupt the circulation each time the center moves over land.  The intermittent passages overland will cause weakening and the intensity of Tropical Depression 01W is likely to fluctuate during the next several days.

A subtropical ridge north of the depression is steering it toward the northwest.  The ridge is forecast to strengthen and it is predicted to steer Tropical Depression 01W in a general westerly direction during the next several days.  On its anticipated track the center of Tropical Depression 01W will pass near northern Mindanao, Siargao Island, Dinogat Island, Leyte, Bohol Island, Cebu, Negros, and Panay Island.

Heavy rain associated will be the greatest threat with Tropical Depression 01W.  The heaviest rain will fall north of where the center moves.  The heavy rain could cause flooding and mudslides,