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Tropical Storm Koto Weakens East of Vietnam

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Tropical Storm Koto weakened as it meandered over the South China Sea east of Vietnam on Sunday.  At 10:00 p.m. EST on Sunday the center of Tropical Storm Koto was located at latitude 14.7°N and longitude 111.6°E which put the center about 200 miles (320 km) east-northeast of Quy Nhon, Vietnam.  Koto was moving toward the southwest 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 1004 mb.

Tropical Storm Koto weakened on Sunday as it moved through a mass of drier air over the western part of the South China Sea.  The drier air caused thunderstorms near the center of Koto’s circulation to dissipate.  Many of the bands revolving around the center of Tropical Storm Koto consisted of showers and lower clouds.  Thunderstorms were still occurring in a couple of bands in the southern part of Koto’s circulation.

There were no thunderstorms near the center of Tropical Storm Koto to generate upper level divergence.  Mass was still converging in the lower levels of the atmosphere.  So, the surface pressure increased on Sunday.

The size of the circulation around Tropical Storm Koto decreased as Koto weakened on Sunday.  Winds to tropical storm force extended out 65 miles (105 km) from the center of Koto’s circulation.

Tropical Storm Koto will be in an environment that will be unfavorable for intensification during the next 24 hours.  Koto will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southeastern part of an upper level ridge that is over the Southeast Asia.  The upper level ridge will produce northeasterly winds that will blow toward the top of Koto’s circulation.  Those winds will cause strong vertical wind shear.  In addition, Tropical Storm Koto will continue to be in a region of drier air that is over the western part of the South China Sea.  The strong vertical wind shear and drier air will continue to cause Tropical Storm Koto to weaken during the next 24 hours.

Since there are no thunderstorms near the center of Tropical Storm Koto, Koto will be steered by the winds in the lower level of the atmosphere.  Koto will move around the southeastern side of a high pressure system that is over Southeast Asia.  The high pressure system will steer Koto toward the southwest during the next 24 hours.  On its anticipated track, Tropical Storm Koto will move toward southern Vietnam.

Tropical Storm Koto Stalls East of Vietnam

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Tropical Storm Koto stalled over the South China Sea east of Vietnam on Saturday.  At 4:00 p.m. EST on Saturday the center of Tropical Storm Koto was located at latitude 13.8°N and longitude 112.2°E which put the center about 200 miles (320 km) east of Quy Nhon, Vietnam.  Koto was moving toward the north at 3 m.p.h. (5 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 998 mb.

Tropical Storm Koto was showing signs of more organization on Saturday afternoon.  More thunderstorms developed near the center of Koto’s circulation.  New thunderstorms also formed in some of the bands revolving around the center of Tropical Storm Koto.  Storms near the center of Koto were not yet generating much upper level divergence.  Mass was still converging in the lower levels of the atmosphere.  So, the surface pressure was increasing.

The distribution of wind speeds around Tropical Storm Koto continued to be asymmetrical. Winds to tropical storm force extended out 125 miles (200 km) in the western side of Koto’s circulation.  Winds to tropical storm force extended out 65 miles (105 km) in the eastern side of Tropical Storm Koto.

Tropical Storm Koto will be in an environment that will be marginally favorable for intensification during the next 24 hours.  Koto will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern part of an upper level ridge that is over the South China Sea.  The upper level ridge will produce southeasterly winds that will blow toward the top of Koto’s circulation.  Those winds will cause some vertical wind shear.  In addition, Tropical Storm Koto will be in a region of drier air that is over the South China Sea.  The vertical wind shear and drier air will inhibit intensification.  Tropical Storm Koto is likely to maintain its intensity during the next 24 hours.  Koto could strengthen a little if the new thunderstorms near the center of circulation begin to generate more upper level divergence.

Tropical Storm Koto will start to move around the southern side of a high pressure system that is over China.  The high pressure system will begin to steer Koto toward the west during the next 24 hours.  On its anticipated track, Tropical Storm Koto will start to move toward Vietnam on Sunday.

Elsewhere, Tropical Depression Senyar was weakening south of Vietnam.  At 4:00 p.m. EST on Saturday the center of Tropical Depression Senyar was located at latitude 6.0°N and longitude 108.9°E which put the center about 380 miles (615 km) south-southeast of Ho Chi Minh City, Vietnam.  Senyar was moving toward the east-northeast at 12 m.p.h. (19 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 1006 mb.

Tropical Storm Koto Meanders East of Vietnam

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Tropical Storm Koto meandered over the South China Sea east of Vietnam on Friday.  At 4:00 p.m. EST on Friday the center of Tropical Storm Koto was located at latitude 13.0°N and longitude 112.5°E which put the center about 235 miles (380 km) east-northeast of Nha Trang, Vietnam.  Koto was moving toward the north at 3 m.p.h. (5 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 993 mb.

Tropical Storm Koto was maintaining its intensity on Friday.  New thunderstorms develop west of the center of Koto’s circulation.  Bands in the other parts of Tropical Storm Koto consisted primarily of showers and lower clouds.  Storms west of the center of Koto generated some upper level divergence that pumped mass away to the northwest of the tropical storm.  The removal of mass in the upper levels was nearly equal to the inflow of mass in the lower levels of the atmosphere.  So, the surface pressure was nearly steady.

The distribution of wind speeds around Tropical Storm Koto continued to be very asymmetrical.  Winds to tropical storm force extended out 180 miles (290 km) in the western side of Koto’s circulation.  Winds to tropical storm force extended out 65 miles (105 km) in the eastern side of Tropical Storm Koto.

Tropical Storm Koto will be in an environment that will be unfavorable for intensification during the next 24 hours.  Koto will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern part of an upper level ridge that is over the South China Sea.  The upper level ridge will produce southeasterly winds that will blow toward the top of Koto’s circulation.  Those winds will cause moderate vertical wind shear.  In addition, Tropical Storm Koto will continue to move through the region of drier air that is over the South China Sea.  Tropical Storm Koto in likely to maintain its intensity during the next 24 hours because of the moderate vertical wind shear and the effects of the drier air.

Tropical Storm Koto will continue to be in a region where the steering currents are weak during the next 24 hours.  On its anticipated track, Tropical Storm Koto will meander slowly over the South China Sea on Friday.

Elsewhere, Tropical Cyclone Senyar moved across Malaysia and over the extreme southwestern part of the Western North Pacific Ocean.  Both the U.S. Joint Typhoon Warning Center and the Japan Meteorological Agency were classifying Senyar as a tropical depression.  At 4:00 p.m. EST on Friday the center of Tropical Depression Senyar was located at latitude 4.8°N and longitude 105.5°E which put the center about 160 miles (260 km) east-northeast of Kuantan, Malaysia.  Senyar was moving toward the east-northeast at 7 m.p.h. (11 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 1003 mb.

Koto Weakens Back to a Tropical Storm

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Former Typhoon Koto weakened back to a tropical storm over the South China Sea on Thursday.  At 4:00 p.m. EST on Thursday the center of Tropical Storm Koto was located at latitude 12.3°N and longitude 113.5°E which put the center about 435 miles (705 km) southeast of Da Nang, Vietnam.  Koto was moving toward the south-southwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 986 mb.

Former Typhoon Koto moved into a region of drier air and weakened back to a tropical storm over the South China Sea on Thursday.  A high pressure system over China was pumping drier air over the South China Sea.  Many of the thunderstorms in Tropical Storm Koto weakened when the drier air was pulled into Koto’s circulation.  Most of the remaining thunderstorms were occurring in bands in the northwestern part of Tropical Storm Koto.  Bands in the other parts of Koto’s circulation consisted primarily of showers and lower clouds.

Storms near the center of Tropical Storm Koto generated less upper level divergence.  The removal of mass in the upper levels of Koto’s circulation was less than the inflow of mass in the lower levels of the atmosphere.  As a result, the surface pressure was increasing.

The distribution of wind speeds in Tropical Storm Koto continued to be very asymmetrical.  Winds to tropical storm force extended out 205 miles (335 km) in the northern side of Koto’s circulation.  Winds to tropical storm force extended out 70 miles (110 km) in the southern side of Tropical Storm Koto.

Tropical Storm Koto will move through an environment that will be unfavorable for intensification during the next 24 hours.  Koto will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the southern part of an upper level ridge that is over the Western North Pacific Ocean.  The upper level ridge will produce southeasterly winds that will blow toward the top of Koto’s circulation.  Those winds will cause moderate vertical wind shear.  In addition, Tropical Storm Koto will continue to move through the region of drier air that is over the western part of the South China Sea.  Moderate vertical wind shear and the effects of drier air will cause Tropical Storm Koto to continue to weaken during the next 24 hours.

Tropical Storm Koto will be in a region where the steering currents are weak during the next 24 hours.  On its anticipated track, Tropical Storm Koto is likely to meander slowly over the South China Sea on Friday.

Koto Intensifies to a Typhoon Over South China Sea

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Former Tropical Storm Koto intensified to a typhoon over the South China Sea on Wednesday.   At 4:00 p.m. EST on Wednesday the center of Typhoon Koto was located at latitude 13.2°N and longitude 114.5°E which put the center about 475 miles (765 km) east-southeast of Da Nang, Vietnam.  Koto was moving toward the northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 982 mb.

Former Tropical Storm Koto intensified to a typhoon on Wednesday.  Thunderstorms continued to develop around the center of Typhoon Koto.  Bands of showers and thunderstorms were revolving around the center of Koto’s circulation.  Storms near the center of Koto generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the surface pressure to decrease.

The distribution of wind speeds around Typhoon Koto was asymmetrical.  Winds to typhoon force extended out 30 miles from the center of Koto’s circulation.  Winds to tropical storm force extended out 205 miles (335 km) in the northern side of Koto’s circulation.  Winds to tropical storm force extended out 70 miles (110 km) in the southern side of Typhoon Koto.

Typhoon Koto will move through an environment that will become unfavorable for intensification during the next 24 hours.  Koto will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the southern part of an upper level ridge that is over the Western North Pacific Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Koto’s circulation.  Those winds will cause the vertical wind shear to increase.  In addition, Typhoon Koto will move into a region of drier air that is flowing over the western part of the South China Sea.  Some of the drier air is likely to get pulled into the western side of Koto’s circulation.  More vertical wind shear and the effects of drier air will cause Typhoon Koto to start to weaken during the next 24 hours.

Typhoon Koto will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Koto toward the west during the next 24 hours.  On its anticipated track, Typhoon Koto will move closer to Vietnam.  A second high pressure system over China and Southeast Asia that is transporting the drier air over the western part of the South China Sea will impede the progress of Koto later this week.  Koto could meander over the South China Sea for several days at the end of the week.

Typhoon Kalmaegi Strikes Central Vietnam

Typhoon Kalmaegi struck central Vietnam on early on Thursday.  At 4:00 a.m. EST on Thursday the center of Typhoon Kalmaegi was located at latitude 13.6°N and longitude 109.9°E which put the center about 50 miles (80 km) southeast of Quy Nohn, Vietnam.  Kalmaegi was moving toward the west-northwest at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 951 mb.

The center of Typhoon Kalmaegi made landfall on the coast of central Vietnam near Song Cau early on Thursday.  Kalmaegi was the equivalent of a major hurricane at the time of landfall.  The maximum sustained wind speed was 125 m.p.h. (200 km/h) at the time of landfall.

At the time of landfall winds to typhoon force extended out 45 miles (75 km) from the center of Kalmaegi’s circulation.  Winds to tropical storm force extended out 160 miles (260 km) from the center center of Typhoon Kalmaegi.

The Hurricane Intensity Index (HII) for Typhoon Kalmaegi at the time of landfall was 23.6.  The Hurricane Size Index (HSI) was 18.4 and the Hurricane Wind Intensity Size Index (HWISI) was 42.0.  Typhoon Kalmaegi was similar in size and intensity to Hurricane Milton when Milton hit Florida in 2024.

Typhoon Kalmaegi will move around the southern side of a high pressure system that is over China.  The high pressure system will steer Kalmaegi toward the west during the next 24 hours.  On its anticipated track, Typhoon Kalmaegi will move inland over central Vietnam during the next few hours.  Kalmaegi will then move near the border between Laos and Cambodia.

Typhoon Kalmaegi will continue to bring strong winds and heavy rain to central Vietnam during the next few hours.  Heavy rain will cause flash floods in some locations.

Typhoon Kalmaegi will weaken steadily as it moves farther inland over Southeast Asia.  Kalmaegi will also drop heavy rain over southern Laos, Cambodia, and northern Thailand.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Fung-wong continued to strengthen gradually east of Yap.  At 4:00 a.m. EST on Thursday the center of Tropical Storm Fung-wong was located at latitude 9.9°N and longitude 140.62E which put the center about 170 miles (280 km) east of Yap.  Fung-wong was moving toward the west-northwest at 3 m.p.h. (5 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 992 mb.  Tropical Storm Fung-wong is forecast to intensify to a typhoon.

Typhoon Kalmaegi Intensifies to Equivalent of a Major Hurricane

Typhoon Kalmaegi intensified to the equivalent of a major hurricane east of Vietnam on Wednesday.  At 4:00 p.m. EST on Wednesday the center of Typhoon Kalmaegi was located at latitude 13.4°N and longitude 113.6°E which put the center about 335 miles (540 km) east-southeast of Quy Nohn, Vietnam.  Kalmaegi was moving toward the west-northwest at 21 m.p.h. (33 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (235 km/h).  The minimum surface pressure was 960 mb.

Typhoon Kalmaegi continued to strengthen on Wednesday as it moved over the South China Sea east of Vietnam.  A small circular eye was at the center of Kalmaegi’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Typhoon Kalmaegi.  Storms near the center of Kalmaegi generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The circulation around Typhoon Kalmaegi was relatively small. Winds to typhoon force extended out 30 miles (50 km) from the center of Kalmaegi’s circulation. Winds to tropical storm force extended out 115 miles (185 km) from the center of Typhoon Kalmaegi.

The Hurricane Intensity Index (HII) for Typhoon Kalmaegi was 20.6.  The Hurricane Size Index (HSI) was 12.5 and the Hurricane Wind Intensity Size Index (HWISI) was 33.1.  Typhoon Kalmaegi was similar in size and intensity to Hurricane Delta when Delta hit Louisiana in 2020.

Typhoon Kalmaegi will move through an environment somewhat favorable for intensification during the next 18 hours.  Kalmaegi will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the southern part of an upper level ridge that is over China.  The upper level ridge will produce easterly winds that will blow toward the top of Kalmaegi’s circulation.  Those winds will cause some vertical wind shear. The vertical wind shear will inhibit intensification but the wind shear may not be enough to prevent intensification.  There is drier air to the north of Kalmaegi.  Typhoon Kalmaegi could intensify during the next 18 hours if the drier air remains north of the typhoon.

Typhoon Kalmaegi will move around the southern side of a high pressure system that is over China.  The high pressure system will steer Kalmaegi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Kalmaegi will reach the coast of central Vietnam in 18 hours.

The center of Typhoon Kalmaegi is likely to make landfall on the coast of Vietnam near Quy Nohn.  Kalmaegi will bring strong winds and heavy rain to central Vietnam.  Heavy rain will cause flash floods in some locations.  Typhoon Kalmaegi could also cause a storm surge of up to 10 feet (3 meters) along parts of the coast.

Typhoon Kalmaegi will also drop heavy rain over southern Laos, Cambodia, and northern Thailand.

Elsewhere over the Western North Pacific Ocean, former Tropical Depression 32W strengthened to Tropical Storm Fung-wong east of Yap.  At 4:00 p.m. EST on Wednesday the center of Tropical Storm Fung-wong was located at latitude 9.7°N and longitude 140.6°E which put the center about 190 miles (305 km) east of Yap.  Fung-wong was moving toward the west-northwest at 14 m.p.h. (22 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.  Tropical Storm Fung-wong is forecast to intensify to a typhoon.

Typhoon Kalmaegi Moves over South China Sea

Typhoon Kalmaegi moved over the South China Sea on Wednesday.  At 10:00 a.m. EST on Wednesday the center of Typhoon Kalmaegi was located at latitude 12.7°N and longitude 115.2°E which put the center about 450 miles (725 km) east-southeast of Quy Nohn, Vietnam.  Kalmaegi was moving toward the west-northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 970 mb.

Typhoon Kalmaegi strengthened again on Wednesday as it moved over the South China Sea.  A new, small circular eye formed at the center of Kalmaegi’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Typhoon Kalmaegi.  Storms near the center of Kalmaegi generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The circulation around Typhoon Kalmaegi was relatively small.  Winds to typhoon force extended out 35 miles (55 km) from the center of Kalmaegi’s circulation.  Winds to tropical storm force extended out 140 miles (225 km) from the center of Typhoon Kalmaegi.

The Hurricane Intensity Index (HII) for Typhoon Kalmaegi was 17.8.  The Hurricane Size Index (HSI) was 12.0 and the Hurricane Wind Intensity Size Index (HWISI) was 29.8.  Typhoon Kalmaegi was similar in size and intensity to Hurricane Sally when Sally hit South Alabama in 2020.

Typhoon Kalmaegi will move through an environment somewhat favorable for intensification during the next 24 hours.  Kalmaegi will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the southern part of an upper level ridge that is over China.  The upper level ridge will produce easterly winds that will blow toward the top of Kalmaegi’s circulation.  Those winds will cause some vertical wind shear.  The vertical wind shear will inhibit intensification but the wind shear may not be enough to prevent intensification.  There is drier air to the north of Kalmaegi.  Typhoon Kalmaegi could intensify during the next 24 hours if the drier air remains north of the typhoon.  Kalmaegi could strengthen to the equivalent of a major hurricane.

Typhoon Kalmaegi will move around the southern side of a high pressure system that is over China.  The high pressure system will steer Kalmaegi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Kalmaegi will reach the coast of central Vietnam in 24 hours.

The center of Typhoon Kalmaegi is likely to make landfall on the coast of Vietnam near Quy Nohn.  Kalmaegi will bring strong winds and heavy rain to central Vietnam.  Heavy rain will cause flash floods in some locations.  Typhoon Kalmaegi could also cause a storm surge of up to 10 feet (3 meters) along parts of the coast.

Typhoon Kalmaegi will also drop heavy rain over southern Laos, Cambodia, and northern Thailand.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 32W  was slowly becoming more organized east of Yap.  At 10:00 a.m. EST on Wednesday the center of Tropical Depression 32W was located at latitude 8.9°N and longitude 142.3°E which put the center about 300 miles (485 km) east of Yap.  The tropical depression was moving toward the west at 8 m.p.h. (13 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 998 mb.  It is forecast to strengthen.

Tropical Storm Fengshen Moves Toward Vietnam

Tropical Storm Fengshen moved toward Vietnam on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Fengshen was located at latitude 17.3°N and longitude 112.2°E which put the center about 290 miles (465 km) east-northeast of Da Nang, Vietnam.  Fengshen was moving toward the southwest at 8 m.p.h. (13 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 993 mb.

Drier air was pulled around the western and southern sides of Tropical Storm Fengshen on Monday.  Bands in the western and southern sides of Fengshen’s circulation consisted primarily of showers and lower clouds.  Thunderstorms were still occurring in bands in the northern and eastern sides of Tropical Storm Fengshen.  Storms near the center of Fengshen still generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass in the upper levels was nearly equal to the inflow of mass in the lower levels of the atmosphere.  So, the surface pressure remained relatively constant on Monday.

The circulation around the northern side of Tropical Storm Fengshen was interacting with a high pressure system over China.  So, tropical storm force winds extended out much farther in the northern half of Fengshen.  Winds to tropical storm force extended out 250 miles (400 km) in the northern side of Tropical Storm Fengshen.  Winds to tropical storm force extended out 140 miles (225 km) in the southern half of Fengshen’s circulation.

Tropical Storm Fengshen will move through an environment marginally favorable for intensification during the next 24 hours.  Fengshen will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the middle of an upper level ridge that is over the South China Sea.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Drier air will continue to be pulled around the northern and western sides of Fengshen’s circulation.  The drier air will inhibit intensification.  Tropical Storm Fengshen is likely to maintain its intensity during the next 24 hours.

Tropical Storm Fengshen will move around the southern side of a high pressure system that is over China.  The high pressure system will steer Fengshen toward the west-southwest during the next 24 hours.  On its anticipated track, Tropical Storm Fengshen will approach the coast of Vietnam near Da Nang in 36 hours.

Tropical Storm Fenshen will bring gusty winds and locally heavy rain to central Vietnam.  Heavy rain could cause floods in some locations.

Halong Strengthens to a Typhoon

Former Tropical Storm Halong strengthened to a typhoon west of the Ogasawara Islands south of Japan on Sunday night.  At 5:00 a.m. EDT on Monday the center of Typhoon Halong was located at latitude 25.9°N and longitude 140.5°E which put the center about 665 miles (1075 km) south of Tokyo, Japan.  Halong was moving toward the west at 7 m.p.h. (11 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 977 mb.

Former Tropical Storm Halong strengthened to a typhoon on Sunday night.  A small circular eye formed at the center of Halong’s circulation.  The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Thunderstorms were also occurring in bands in the eastern side of Typhoon Halong.  Bands in the western side of Halong’s circulation consisted primarily of showers and lower clouds.  Storms near the center of Halong generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The distribution of wind speeds in Typhoon Halong was relatively symmetrical.  Winds to typhoon force extended out 25 miles (40 km) from the center of Halong’s circulation.  Winds to tropical storm force extended out 115 miles (185 km) from the center of Typhoon Halong.

Typhoon Halong will move through an environment that is mostly favorable for intensification during the next 24 hours.  Halong will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the middle of an upper level ridge that is south of Japan.  The upper level winds are weak near the middle of the upper level ridge and there will be little vertical wind shear.  However, Halong will move into a region of drier air.  The drier air will inhibit the formation of thunderstorms in the western part of Halong’s circulation.  Typhoon Halong is likely to intensify during the next 24 hours if the drier air does not get pulled into the core of Halong.

Typhoon Halong will move around the southwestern part of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Halong toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Halong will move a little closer to Japan.

Elsewhere, the center of Tropical Storm Matmo moved over northeastern Vietnam.  At 5:00 a.m. EDT on Monday the center of Tropical Storm Matmo was located at latitude 22.4°N and longitude 106.2°E which put the center about 25 miles (40 km) east of Na Phac, Vietnam.  Matmo was moving toward the west-northwest 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 1000 mb.