Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Tropical Storm Tembin Strengthens Over the Sulu Sea

Tropical Storm Tembin moved west of Mindanao and it strengthened over the Sulu Sea on Friday.  At 4:00 p.m. EST on Friday the center of Tropical Storm Tembin was located at latitude 8.0°N and longitude 120.8°E which put it about 200 miles (320 km) southeast of Puerto Princesa, Philippines.  Tembin was moving toward the west at 8 m.p.h. (13 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 992 mb.

Tropical Storm Tembin weakened when the center moved across Mindanao.  The center is back over water in the Sulu Sea and the circulation of Tembin is strengthening again.  There is a distinct low level center of circulation, but the distribution of thunderstorms is asymmetrical.  Most of the strong thunderstorms are occurring in bands in the western half of the circulation.  Bands in the eastern half of the circulation consist primarily of low clouds and showers.  The storms west of the center are generating upper level divergence which is pumping mass away to the west of the tropical storm.  The removal of mass has caused the surface pressure to decrease and the wind speeds have started to increase.

Tropical Storm Tembin will be moving through an environment that is favorable for intensification.  Tembin will move over water where the Sea Surface Temperature is near 29°C.  An upper level ridge north of Tropical Storm Tembin is producing easterly winds which are blowing toward the top of the circulation.   Those winds are causing vertical wind shear, which is probably the reason for the asymmetrical distribution of thunderstorms.  However, the shear is not strong enough to prevent Tropical Storm Tembin from intensifying.  Tembin could strengthen into a typhoon during the next day or two while is moves over the South China Sea.

The subtropical ridge north of Tembin is steering the tropical storm toward the west.  A general motion toward the west-northwest west is forecast for the next two or three days.  On its anticipated track Tropical Storm Tembin will move across Palawan in about 18 hours.  Tembin could reach the southern coast of Vietnam in about three days.  Tembin will bring gusty winds and heavy rain to Palawan.  Tembin could be a typhoon when it approaches southern Vietnam.

Elsewhere over the western North Pacific Ocean Tropical Depression Kai-tak is approaching the east coast of Malaysia.  At 4:00 p.m. EST on Friday the center of Tropical Depression Kai-tak was located at latitude 4.0°N and longitude 104.4°E which put it about 175 miles (285 km) north-northeast of Singapore.  Kai-tak was moving toward the southwest at 8 m.p.h. (13 km/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 1005 mb.  Tropical Depression Kai-tak will drop locally heavy rain over portions of Malaysia, which could cause floods and mudslides.

Tropical Storm Tembin Drops Heavy Rain on Mindanao

Tropical Storm Tembin dropped heavy rain on Mindanao on Thursday.  At 4:00 p.m. EST on Thursday the center of Tropical Storm Tembin was located at latitude 7.9°N and longitude 126.1°E which put it near Monkayo, Philippines.  Tembin was moving toward the west-southwest at 12 m.p.h. (19 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 990 mb.

Tropical Storm Tembin intensified on Thursday before it made landfall on Mindanao.  More thunderstorms developed near the core of the circulation and those storms generated stronger upper level divergence which pumped mass away from the tropical storm.  The removal of mass allowed the surface pressure to decrease and the wind speed to increase.  Although the circulation became much better organized, the distribution of thunderstorms was still asymmetrical.  There were far fewer thunderstorms forming in the eastern half of the circulation.

The center of Tropical Storm Tembin will be moving across Mindanao for another day or so.  The mountains on the island will disrupt the lower levels of the circulation and increased friction will slow the wind speed.  Tropical Storm Tembin will weaken while the center is over Mindanao.  However, the middle and upper parts of the circulation are likely to remain intact, and Tropical Storm Tembin will move through a favorable environment when it reaches the Sulu Sea.  Tembin will move over water where the Sea Surface Temperature is near 29°C.  An upper level ridge north of Tropical Storm Tembin is producing easterly winds which are blowing toward the top of the circulation.  The winds in the middle and lower levels are also blowing from the east and the vertical wind shear will not be strong enough to prevent intensification of Tropical Storm Tembin once the center gets back over water.  Temping could strengthen into a typhoon when it reaches the South China Sea.

The ridge north of Tembin is steering the tropical storm toward the west-southwest.  A general motion toward the west is expected during the next two to three days.  On its anticipated track Tropical Storm Tembin will move east to west over Mindanao during the next 24 hours.  Afterwards, Tropical Storm Tembin will move across the Sulu Sea toward Palawan.  Tembin could be near Palawan in about 48 hours and it could be over the South China Sea shortly thereafter.

Tropical Storm Tembin represents a serious hazard for Mindanao and nearby locations in the southern Philippines.  Tembin is dropping heavy rain and it has the potential to cause serious floods.  Water levels could rise quickly and flash floods could develop.  Saturated soils could result in mudslides in areas of steeper terrain.

Farther to the west, Tropical Storm Kai-tak continued to move across the South China Sea.  At 4:00 p.m. EST on Thursday the center of Tropical Storm Kai-tak was located at latitude 5.7°N and longitude 106.9°E which put it about 250 miles (400 km) east of Kuala Terengganu, Malaysia.  Kai-tak was moving toward the west-southwest at 5 m.p.h. (8 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.

Tropical Storm Tembin Forms East of the Philippines

Tropical Storm Tembin formed east of the Philippines on Wednesday.  At 1:00 p.m. EST on Wednesday the center of Tropical Storm Tembin was located at latitude 9.0°N and longitude 130.7°E which put it about 270 miles (435 km) east of Mindanao.  Tembin was moving toward the west at 12 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.

A more well organized center of circulation developed on the eastern edge of a cluster of thunderstorms east of the Philippines and the Japan Meteorological Agency classified the system as Tropical Storm Tembin.  The distribution of thunderstorms in Tembin is asymmetrical.  Most of the storms are forming in bands north and west of the center of circulation.  Those storms are generating upper level divergence which is pumping mass away from the core of Tembin.  There are a few thunderstorms in bands on the eastern periphery of the circulation, but most of the bands in the eastern half of Tropical Storm Tembin contain only low clouds and showers.

Tropical Storm Tembin will be moving through an environment favorable for intensification during the next several days.  Tembin will move over water where the Sea Surface Temperature is near 29°C.  An upper level ridge north of Tembin is producing easterly winds which are blowing toward the top of the circulation.  Those winds are causing moderate vertical wind shear and they are probably the reason why most of the thunderstorms are developing west of the center of circulation.  However, the shear has not been enough to prevent Tembin from organizing and Tembin is likely to strengthen during the next 24 hours.  The center of Tembin will move over Mindanao later on Thursday and it will weaken while the center is over land.  Tropical Storm Tembin will likely intensify once the center moves west of Mindanao.

A subtropical ridge north of Tembin is steering the tropical storm toward the west and a general westerly motion is expected to continue for several more days.  On its anticipated track the center of Tropical Storm Tembin could approach Mindanao in about 24 hours.  Tembin is then forecast to move over the Bohol Sea and Sulu Sea and on toward Palawan.  It currently looks like Tropical Storm Tembin will take a track a little to the south of the track taken by Tropical Storm Kai-tak across the Philippines last week.

Tropical Storm Tembin will drop heavy rain over parts of Mindanao, southern Leyte, Bohol, Cebu, Negros, Siargao, and Dinagat.  The heavy rain could cause floods and mudslides.  The northern part of Tropical Storm Tembin could drop heavy rain in some of the places affected by Tropical Storm Kai-tak last week.  Any additional rain in those locations would hamper efforts to recover from floods and mudslides caused by Kai-tak.

Tropical Storm Kai-Tak continue to move southwest over the South China Sea.  At 4:00 p.m. EST on Wednesday the center of Tropical Storm Kai-tak was located at latitude 6.4°N and longitude 111.1°E which put it about 440 miles (710 km) southeast of Ho Chi Minh City, Vietnam.  Kai-tak was moving toward the southwest at 7 m.p.h. (11 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 998 mb.

Tropical Storm Kai-tak Moves Over South China Sea

Tropical Storm Kai-tak moved west of the Philippines and over the South China Sea on Tuesday.  At 10:00 p.m. EST on Tuesday the center of Tropical Storm Kai-tak was located at latitude 8.2°N and longitude 112.0°E which put it about 425 miles (685 km) east-southeast of Ho Chi Minh City, Vietnam.  Kai-tak was moving toward the west-southwest at 12 m.p.h. (19 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 organization of the circulation of Tropical Storm Kai-tak improved on Tuesday.  More thunderstorms developed near the center of circulation.  The two stronger rainbands were north and west of the center.  However, thunderstorms also developed in a couple of bands southeast of the center of circulation.  These storms were the first to form in the eastern half of the circulation in several days.  The distribution of the rainbands was still asymmetrical, but storms were occurring in more quadrants of Kai-tak.  The storms in the two stronger rainbands were generating some upper level divergence which was pumping mass away to the west of the tropical storm.

Tropical Storm Kai-tak will be moving through an environment somewhat favorable for intensification during the next day or two.  Kai-tak will move over water where the Sea Surface Temperature is near 29°C.  Kai-tak is moving near the southwestern portion of a subtropical ridge.  The ridge is producing easterly winds which are blowing toward the top of the circulation.  The easterly winds are causing moderate vertical wind shear, but they have weakened somewhat during the past 24 hours.  Less wind shear has allowed Tropical Storm Kai-tak to become better organized.  Tropical Storm Kai-tak could strengthen during the next 24 to 36 hours.

The western end of the subtropical ridge is strengthening and the ridge is steering Tropical Storm Kai-tak toward the west-southwest.  A general motion toward the west-southwest is expected to continue for the next two or three days.  On its anticipated track the center of Tropical Storm Kai-tak is expected to pass south of the southern tip of Vietnam.  Kai-tak is forecast to stay north of Borneo.  The center of Tropical Storm Kai-tak could approach the region near the border between Thailand and Malaysia in about 72 hours.

Tropical Storm Kai-tak Weakens Over the Philippines

Tropical Storm Kai-tak weakened as it passed over the Philippines.   Kai-tak dropped heavy rain which caused floods and mudslides before it weakened.  At 10:00 p.m. EST on Sunday the center of Tropical Storm Kai-tak was located at latitude 10.5°N and longitude 119.1°E which put it about 75 miles (120 km) northeast of Puerto Princesa, Philippines.  Kai-tak was moving toward the west-southwest 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 1000 mb.

Moving over islands of the central Philippines disrupted parts of the circulation of Tropical Storm Kai-tak.  In addition an upper level ridge produced strong easterly winds which blew across the top of the circulation.  Those winds caused moderate vertical wind shear.  The strong upper level winds periodically weakened the thunderstorms near the core of the circulation.  The upper level winds slowed at times and more storms developed near the center of Tropical Storm Kai-tak.  The persistent vertical wind shear weakened the low level circulation.

More thunderstorms developed near the center of Tropical Storm Kai-tak during recent hours, but the circulation remains asymmetrical.  The new storms were forming west of the center of circulation.  There were only a few thin bands of showers in the eastern half of the circulation.  The strongest winds were occurring in the thunderstorms west of the center of Tropical Storm Kai-tak.  The Japan Meteorological Agency was maintaining a classification of a tropical storm.

Tropical Storm Kai-tak will move through an environment only marginally favorable for intensification.  Kai-tak will move over water where the Sea Surface Temperature is near 29°C.  The upper level ridge will continue to produce strong easterly winds and there will continue to be moderate vertical wind shear.  Tropical Storm Kai-tak could maintain its intensify, if the wind shear does not increase.  However, if the upper level winds get stronger, then they could blow the top off of the circulation.

Tropical Storm Kai-tak is moving south of a subtropical ridge which is steering the tropical storm toward the west-southwest.  The west-southwesterly motion is forecast to continue for another day or two.  On its anticipated track Tropical Storm Kai-tak will move across Palawan and over the South China Sea.

Tropical Storm Kai-tak Drops Heavy Rain on Philippines

Tropical Storm Kai-tak dropped heavy rain on places in the Philippines during the past several days.  At 4:00 p.m. EST on Friday the center of Tropical Storm Kai-tak was located at latitude 12.1°N and longitude 126.8°E which put it about 150 miles (240 km) east-northeast of Tacloban, Philippines.  Kai-tak was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 996 mb.

The distribution of thunderstorms around Tropical Storm Kai-Tak remains asymmetrical.  Kai-tak is south of an upper level ridge which is producing easterly winds which are blowing toward the top of the tropical storm.  Those winds are causing moderate vertical wind shear and most of the thunderstorms are developing in the western half of the circulation.  The magnitude of the vertical wind shear fluctuates as the speed of the upper level winds increases or decreases.  Changes in the magnitude of the wind shear contributes to fluctuations in the intensity of the thunderstorms.  When the shear is stronger, most of the storms develop in the outer portion of the circulation of Kai-tak.  When the upper level winds slow, thunderstorms are able to develop closer to the western core of the tropical storm.  Daytime warming of the surface of some of the islands in the Philippines may increase the local instability, which also contributes to the formation of storms over those islands.

Tropical Storm Kai-tak moved very little during the past two days.  As a result, heavy rain fell repeatedly over portions of Samar, Leyte, Bohol, Cebu, Negros, Panay, Masbate and southeastern Luzon.  The heavy rain is creating the potential for floods and mudslides in those areas.

Tropical Storm Kaitak will move through an environment that is only marginally favorable for development.  Kai-tak will move over water where the Sea Surface Temperature is near 29°C.  However, the upper level ridge will continue to cause moderate vertical wind shear.  Tropical Storm Kai-tak could intensify a little during the next 24 hours, but the wind shear will limit the potential for strengthening.  Tropical Storm Kai-tak is likely to weaken when the center of circulation passes over islands in the Philippines.

The subtropical ridge north of Kai-tak is steering the tropical storm toward the northwest.  The ridge is forecast to strengthen during the weekend and it is likely to steer Tropical Storm Kai-tak more toward the west during the next 24 to 36 hours.  On its anticipated track the center of Kai-tak could reach Samar in the next 12 to 18 hours.  The center could then move near Masbate and Panay.

Tropical Storm Kai-tak will continue to drop locally heavy rain on places in Samar, Leyte, Bohol, Cebu, Panay, Negros, Masbate and southern Luzon for several more days.  The heaviest rain will fall in locations where the wind pushes air up the slopes of mountains.  The potential for floods and mudslides will increase as more rain falls.

Tropical Storm Kai-tak Develops East of the Philippines

A tropical depression east of the Philippines strengthened on Wednesday and the Japan Meteorological Agency designated the system as Tropical Storm Kai-tak.  At 10:00 p.m. EST on Wednesday the center of Tropical Storm Kai-tak was located at latitude 11.2°N and longitude 127.2°E which put it about 150 miles (240 km) east of Tacloban, Philippines.  Kai-tak was moving toward the west-northwest at 4 m.p.h. (6 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 circulation of Tropical Storm Kai-tak strengthened on Wednesday, but the distribution of thunderstorms was still asymmetrical.  Most of the stronger storms were occurring in bands in the western half of the circulation.  There were few thunderstorms in the eastern half of Kai-tak.  The center of circulation was located near the eastern edge of the strong thunderstorms.  The storms in the western half of the circulation were generating upper level divergence which was pumping mass away to the west of the tropical storm.

Tropical Storm Kai-tak will move through an environment that is marginally favorable for intensification.  Kai-tak 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 an upper level ridge east of the Philippines is producing easterly winds which are blowing toward the top of the circulation.  Those winds are causing moderate vertical wind shear and the shear is probably the reason for the asymmetrical distribution of thunderstorms.  The moderate shear will limit the intensification of Tropical Storma Kai-tak.  Kai-tak could intensify slowly during the next day or two.  The center of Kai-tak will pass over some of the Philippines and the interaction with those islands will weaken the tropical storm.

The winds at the steering levels are weaker than the upper level easterlies.  Tropical Storm Kai-tak is forecast to move slowly toward the west-northwest during the next several days, but it could be nearly stationary at times.  On its anticipated track the center of Tropical Storm Kai-tak could move very near Samar during the next 24 to 48 hours.

Tropical Storm Kai-tak is already dropping heavy rain over parts of Samar and Leyte.  The slow movement of Kai-tak could result in prolonged periods of heavy rain in that region.  The heavy rain has the potential to cause serious floods and mudslides.

Tropical Storm Kirogi Brings Rain to Southern Vietnam

Tropical Storm Kirogi brought locally heavy rain to southern Vietnam on Saturday night.  At 10:00 p.m. EST on Saturday night the center of Tropical Storm Kirogi was located at latitude 10.4°N and longitude 109.8°E which put it about 220 miles (355 km) east of Ho Chi Minh City, Vietnam.  Kirogi was moving toward the west at 13 m.p.h. (21 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 1001 mb.

Kirogi is a small tropical storm.  Winds to tropical storm force extend out about 90 miles (145 km) from the center of circulation.  The circulation is compact and circular.  Most of the strong storms are in the western half of the circulation.  There are numerous bands of lighter showers in eastern half of the circulation.  An upper level ridge north of Kirogi is producing easterly winds which are blowing toward the top of the circulation.  The vertical wind shear is causing the asymmetrical distribution of the stronger storms.

The ridge is steering Tropical Storm Kirogi toward the west.  The center of Tropical Storm Kirogi will make landfall on the coast of Vietnam near Ham Thuan Nam in a few hours.  Kirogi will continue moving west toward Ho Chi Minh City and then over southeastern Cambodia.  Tropical Storm Kirogi will drop locally heavy rain along the coast from Nha Trang to the Mouths of the Mekong River.  Kirogi will also be capable of producing heavy heavy over parts of the southern Cambodia.  The rainfall could be heavy enough to cause flooding in some locations.

Tropical Storm Kirogi Forms West of the Philippines

Tropical Storm Kirogi formed west of the Philippines on Friday.  At 4:00 p.m. EST on Friday the center of Tropical Storm Kirogi was located at latitude 10.9°N and longitude 115.7°E which put it about 465 miles (745 km) east of Nha Trang, Vietnam.  Kirogi was moving toward the west-northwest at 18 m.p.h. (30 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.

A low level center of circulation developed near the eastern edge of an area of showers and thunderstorms west of the Philippines on Friday and the Japan Meteorological Agency designated the system as Tropical Storm Kirogi.  The distribution of showers and thunderstorms in Kirogi was asymmetrical.  A primary rainband wrapped around the western side of the center of circulations and most of the stronger storms were west of the center.  There were only bands of low clouds and showers east of the center of Kirogi.  An upper level ridge north of Kirogi was producing easterly winds which were blowing across the top of the tropical storm.  The vertical wind shear created by those winds was causing the asymmetrical distribution of showers and thunderstorms.

Tropical Storm Kirogi will move through an environment that will be somewhat favorable for intensification.  Kirogi will move over water where the Sea Surface Temperature is near 29°C.  The upper level ridge will continue to cause vertical wind shear.  The shear may be strong enough to slow intensification, but it may not strong enough to prevent Tropical Storm Kirogi from strengthening.  The forecast is for Tropical Storm Kirogi to intensify during the next 24 to 36 hours.

The ridge is steering Tropical Storm Kirogi toward the west-northwest and a general westerly motion is expected to continue.  On its anticipated track Tropical Storm Kirogi will move across the South China Sea toward Vietnam.  Kirogi could reach the coast of Vietnam near Nha Trang in about 36 hours.  Kirogi will bring gusty winds and locally heavy rain when it reaches the coast.  The locally heavy rain could cause flash floods.  There could also be a storm surge of 3 to 6 feet (1 to 2 meters) where the wind blows water toward the coast of Vietnam.

Remnants of Tropical Storm Haikui Make Landfall in Vietnam

The remnants of Tropical Storm Haikui made landfall near Da Nang, Vietnam late on Monday.  At 10:00 p.m. EDT on Monday the center of Tropical Depression Haikui were located at latitude 17.0°N and longitude 108.2°E which put it about 20 miles (30 km/h) north of Da Nang, Vietnam.  Haikui was moving toward the west at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 25 m.p.h. (40 km/h) and there were wind gusts to 35 m.p.h. (55 km/h).  The minimum surface pressure was 1003 mb.

The remnants of Tropical Storm Haikui consists of primarily of a low level counterclockwise circulation.  There are several thin bands of low clouds and showers.  Stronger thunderstorms were forming near the core of the circulation.  It appeared that winds blowing toward the coast were converging due to increased friction caused by the land.  The convergence was causing stronger rising motion which was contributing to the development of strong thunderstorms near and to the west of the center of circulation.

The remnants of Tropical Storm Haikui will move inland before significant intensification can occur.  The remnants of Haikui could drop locally heavy rainfall over portions of Vietnam, southern Laos and northeastern Thailand.  Locally heavy rainfall could cause flooding in some places.