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Typhoon Sinlaku Batters Tinian and Saipan

Typhoon Sinlaku battered Tinian and Saipan on Tuesday.  At 11:00 a.m. EDT on Tuesday the center of Typhoon Sinlaku was located at latitude 15.1°N and longitude 145.7°E which put the center about 20 miles (30 km) south of Saipan.   Sinlaku was moving toward the northwest at 5 m.p.h. (8 km/h).   The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 175 m.p.h. (285 km/h).  The minimum surface pressure was 930 mb.

Typhoon Warnings are in effect for Rota, Tinian, Saipan, Pagan, Alamagan, and Agrihan.

A Tropical Storm Warning is in effect for Guam.

A Typhoon Watch is also in effect for Guam.

A weather station at the international airport in Saipan reported a sustained wind speed of 82 m.p.h. (132 km) and a wind gust of 130 m.p.h. (210 km/h) as the eyewall of Typhoon Sinlaku passed over it.

Typhoon Sinlaku began an eyewall replacement cycle just before it reached Tinian and Saipan.  A larger, outer eyewall formed around the smaller, original eyewall.  The low level convergence began to be intercepted by the outer eyewall and the original inner eyewall began to weaken.  The weakening of the inner eyewall caused the strongest winds in Typhoon Sinlaku to diminish very gradually.

The remnant of the original inner eyewall was still visible on satellite and radar images of Typhoon Sinlaku.  The larger outer eyewall appeared to be becoming the predominant feature in the core of Sinlaku’s circulation.  Bands of showers and thunderstorms were revolving around the core of Typhoon Sinlaku.  Storms near the core of Sinlaku generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels of the atmosphere was less than the strong convergence of mass in the lower levels.  So, the surface pressure was increasing gradually.

The circulation around Typhoon Sinlaku was large.  Winds to typhoon force extended out 75 miles (120 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 265 miles (425 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku is 29.9.  The Hurricane Size Index (HSI) is 27.4 and the Hurricane Wind Intensity Size Index (HWISI) is 57.3. Typhoon Sinlaku is similar in size and intensity to Hurricane Helene when Helene hit Florida in 2024.

Typhoon Sinlaku started to move more slowly as it began the eyewall replacement cycle.  The slower movement was prolonging the period destructive wind and rain in Tinian and Saipan.  Sinlaku was capable of causing severe damage.  Prolonged heavy rain is likely to cause flash floods.

Flood Watches are in effect for Guam, Rota, Tinian, and Saipan.

Typhoon Sinlaku could cause a storm surge of up to 13 feet (4 meters).

Typhoon Sinlaku will move around the western part of a high pressure system that is over the Western North Pacific Ocean. The high pressure system will steer Sinlaku toward the north-northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Sinlaku will move very slowly away from Tinian and Saipan.  Sinlaku will be west of the Marianas on Wednesday.

Typhoon Sinlaku will move into an environment that will be marginally favorable for a strong typhoon during the next 24 hours.  Sinlaku 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 Western North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Sinlaku will move into a region where the air is drier.  The drier air is likely to inhibit the development of thunderstorms in the northern and western parts of Sinlaku’s circulation.  Typhoon Sinlaku is likely to continue to weaken gradually during the next 24 hours because of the eyewall replacement cycle and the drier air.

Typhoon Sinlaku Nears Tinian and Saipan

The center of Typhoon Sinlaku was nearing Tinian and Saipan on Monday evening.  At 11:00 p.m. EDT on Monday the center of Typhoon Sinlaku was located at latitude 14.5°N and longitude 146.3°E which put the center about 75 miles (120 km) southeast of Saipan.  Sinlaku was moving toward the northwest at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 155 m.p.h. (250 km/h) and there were wind gusts to 190 m.p.h. (305 km/h).  The minimum surface pressure was 919 mb.

Typhoon Warnings are in effect for Rota, Tinian, Saipan, Pagan, Alamagan, and Agrihan.

A Tropical Storm Warning is in effect for Guam.

A Typhoon Watch is also in effect for Guam.

Typhoon Sinlaku weakened just slightly as it neared Tinian and Saipan on Monday evening.  A circular eye with a diameter of 20 miles (32 km) was visible at the center of Sinlaku’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 Sinlaku.  Storms near the center of Sinlaku generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels of the atmosphere was less than the strong convergence of mass in the lower levels.  So, the surface pressure was increasing gradually.

The circulation around Typhoon Sinlaku was large.  Winds to typhoon force extended out 75 miles (120 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 265 miles (425 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku is 33.3.  The Hurricane Size Index (HSI) is 29.6 and the Hurricane Wind Intensity Size Index (HWISI) is 62.9.  Typhoon Sinlaku is similar in intensity to Hurricane Ian when Ian hit Southwest Florida in 2022.  Sinlaku is bigger than Ian was.

Typhoon Sinlaku will move into an environment that will become a little less favorable for a strong typhoon during the next 24 hours.  Sinlaku 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 Western North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Sinlaku will move into a region where the air is drier.  The drier air is likely to inhibit the development of thunderstorms in the northern and western parts of Sinlaku’s circulation.  Typhoon Sinlaku is likely to continue to weaken gradually during the next 24 hours because of the drier air.

Typhoon Sinlaku will move around the western part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Sinlaku will reach Tinian and Saipan in a few hours.

Typhoon Sinlaku will be the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale when it reaches Tinian and Saipan.  Sinlaku will be capable of causing severe damage in Tinian and Saipan.  Typhoon Sinlaku will bring also strong winds and locally heavy rain to Guam, Rota, Pagan, Alamagan, and Agrihan. Heavy rain is likely to cause flash floods in some locations.

A Flash Flood Warning is in effect for Guam.

Flood Watches are in effect for  Rota, Tinian, and Saipan.

Typhoon Sinlaku could also cause a storm surge of up to 15 feet (4.5 meters) along parts of the coasts of the Marianas.

Typhoon Sinlaku Bears Down on the Marianas

Typhoon Sinlaku was bearing down on the Marianas on Monday morning.  At 11:00 a.m. EDT on Monday the center of Typhoon Sinlaku was located at latitude 13.3°N and longitude 147.2°E which put the center about 190 miles (335 km) east of Guam.  Sinlaku was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 175 m.p.h. (285 km/h) and there were wind gusts to 205 m.p.h. (335 km/h).  The minimum surface pressure was 903 mb.

Typhoon Warnings are in effect for Rota, Tinian, and Saipan.

Tropical Storm Warnings are in effect for Guam, Pagan, and Alamagan.

A Typhoon Watch is in effect for Guam.

A Tropical Storm Watch is in effect for Agrihan.

Typhoon Sinlaku was maintaining its intensity as it was bearing down on the Mariana’s on Monday morning.  Sinlaku was the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.  A circular eye with a diameter of 17 miles (28 km) was as the center of Sinlaku’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 Sinlaku.  Storms near the center of Sinlaku generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels of the atmosphere was nearly equal to the convergence of mass in the lower levels.  So, the surface pressure was nearly constant.

The circulation around Typhoon Sinlaku was large.  Winds to typhoon force extended out 80 miles (130 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 290 miles (465 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku is 40.4.  The Hurricane Size Index (HSI) is 28.4 and the Hurricane Wind Intensity Size Index (HWISI) is 68.8.  Typhoon Sinlaku is similar in intensity to Hurricane Maria when Maria was at its peak strength in 2017.  Sinlaku is bigger than Maria was.

Typhoon Sinlaku will move through an environment favorable for a very powerful typhoon during the next 24 hours.  Sinlaku 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 Western North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Sinlaku is likely to maintain its intensity during the next 24 hours unless an eyewall replacement cycle occurs.  Sinlaku could weaken if the inner end of a rainband wraps around the existing eye and eyewall.  If concentric eyewalls form, then an eyewall replacement cycle would cause Typhoon Sinlaku to weaken.

Typhoon Sinlaku will move around the western part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Sinlaku will be near Tinian and Saipan in less than 24 hours.

Typhoon Sinlaku could be the equivalent of a Category 5 hurricane when it reaches Tinian and Saipan.  Sinlaku will be capable of causing catastrophic damage in Tinian and Saipan.  Typhoon Sinlaku will bring also strong winds and locally heavy rain to Guam, Rota, Pagan, and Alamagan. Heavy rain is likely to cause flash floods in some locations.

Flood Watches are in effect for Guam, Rota, Tinian, and Saipan.

Typhoon Sinlaku could also cause a storm surge of up to 17 feet (5.1 meters) along parts of the coasts of the Marianas.

Typhoon Sinlaku Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Sinlaku intensified to the equivalent of a category 5 hurricane on the Saffir-Simpson Scale on Sunday.  At 11:00 a.m. EDT on Sunday the center of Typhoon Sinlaku was located at latitude 11.4°N and longitude 149.9°E which put the center about 410 miles (660 km) east-southeast of Guam.  Sinlaku was moving toward the north-northwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 175 m.p.h. (285 km/h) and there were wind gusts to 205 m.p.h. (335 km/h).  The minimum surface pressure was 902 mb.

Typhoon Warnings were in effect for Rota, Tinian, and Saipan.

A Tropical Storm Warning was in effect for Guam.

A Typhoon Watch was also in effect for Guam.

Typhoon Sinlaku rapidly intensified to the equivalent of a Category 5 hurricane on Sunday.  A circular eye with a diameter of 20 miles (32 km) was as the center of Sinlaku’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 Sinlaku.  Storms near the center of Sinlaku 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 Sinlaku was large.  Winds to typhoon force extended out 60 miles (95 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 275 miles (445 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku is 40.4.  The Hurricane Size Index (HSI) is 21.3 and the Hurricane Wind Intensity Size Index (HWISI) is 61.7.  Typhoon Sinlaku is similar in size and intensity to Hurricane Maria when Maria was at its peak strength in 2017.

Typhoon Sinlaku will move through an environment favorable for a very powerful typhoon during the next 24 hours.  Sinlaku 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 over the Western North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Sinlaku is likely to maintain its intensity during the next 24 hours unless an eyewall replacement cycle occurs.  Sinlaku could weaken if the inner end of a rainband wraps around the existing eye and eyewall.  If concentric eyewalls form, then an eyewall replacement cycle would cause Typhoon Sinlaku to weaken.

Typhoon Sinlaku will move around the western part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Sinlaku will approach the Marianas in less than 35 hours.

Typhoon Sinlaku will be the equivalent of a major hurricane when it approaches the Marianas.  Sinlaku will bring very strong winds and locally heavy rain to Guam, Rota, Tinian, and Saipan.   Heavy rain is likely to cause flash floods in some locations.

Flood Watches are in effect for Guam, Rota, Tinian, and Saipan.

Typhoon Sinlaku could also cause a storm surge of up to 17 feet (5.1 meters) along parts of the coasts of the Marianas.

Typhoon Sinlaku Intensifies to Equivalent of a Major Hurricane

Typhoon Sinlaku intensified to the equivalent of a major hurricane as it moved southeast of the Marianas on Saturday evening.  At 11:00 p.m. EDT on Saturday the center of Typhoon Sinlaku was located at latitude 10.2°N and longitude 151.0°E which put the center about 505 miles (815 km) east-southeast of Guam.  Sinlaku was moving toward the north-northwest at 9 m.p.h. (15 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 944 mb.

Typhoon Watches are in effect for Guam, Rota, Tinian, and Saipan.

Typhoon Sinlaku continued to strengthen on Saturday evening as it moved toward the southern Marianas.  A circular eye with a diameter of 20 miles (32 km) was as the center of Sinlaku’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 Sinlaku.  Storms near the center of Sinlaku 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 Sinlaku was large.  Winds to typhoon force extended out 60 miles (95 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 250 miles (400 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku was 23.6.  The Hurricane Size Index (HSI) was 21.2 and the Hurricane Wind Intensity Size Index (HWISI) was 44.8.

Typhoon Sinlaku will move through an environment favorable for intensification during the next 24 hours.  Sinlaku 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 over the Western North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Sinlaku will intensify during the next 24 hours.  Sinlaku could intensify rapidly at times.  Typhoon Sinlaku could strengthen to the equivalent of a Category 5  hurricane on the Saffir-Simpson Scale during the next 36 hours.

Typhoon Sinlaku will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the northwest during the next 24 hours. On its anticipated track, Typhoon Sinlaku will approach the southern Marianas in less than 48 hours.

Typhoon Sinlaku will be the equivalent of a major hurricane when it approaches the southern Marianas.  Sinlaku will bring very strong winds and locally heavy rain to Guam, Rota, Tinian, and Saipan.  Heavy rain is likely to cause flash floods in some locations.

Flood Watches are in effect for Guam, Rota, Tinian, and Saipan.

Typhoon Sinlaku could also cause a storm surge of up to 14 feet (4.3 meters) along parts of the coasts of the southern Marianas.

Sinlaku Causes Typhoon Watch for Guam

The threat posed by Typhoon Sinlaku caused a Typhoon Watch to be issued for Guam, Rota, Tinian, and Saipan on Saturday.  At 11:00 a.m. EDT on Saturday the center of Typhoon Sinlaku was located at latitude 9.2°N and longitude 150.9°E which put the center about 535 miles (865 km) southeast of Guam.  Sinlaku was moving toward the northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 965 mb.

Typhoon Watches are in effect for Guam, Rota, Tinian, and Saipan.

Typhoon Sinlaku continued to strengthen on Saturday as it moved toward the southern Marianas.  A small circular eye was as the center of Sinlaku’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 Sinlaku.  Storms near the center of Sinlaku generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The size of the circulation around Typhoon Sinlaku continued to increase on Saturday.  Winds to typhoon force extended out 50 miles (80 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 250 miles (400 km) in the northeastern quadrant of Typhoon Sinlaku.  Winds to tropical storm force extended out 165 miles (265 km) in the other quadrants of Sinlaku’s circulation.

Typhoon Sinlaku will move through an environment favorable for intensification during the next 24 hours.  Sinlaku will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is over the Western North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Sinlaku will intensify during the next 24 hours.  Sinlaku could intensify rapidly at times. Typhoon Sinlaku is likely to strengthen to the equivalent of a major hurricane during the weekend.

Typhoon Sinlaku will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Sinlaku will move toward the southern Marianas.  Sinlaku will approach Guam in 48 hours.

Typhoon Sinlaku will be the equivalent of a major hurricane when it approaches the southern Marianas.  Sinlaku could bring very strong winds and locally heavy rain to Guam, Rota, Tinian, and Saipan.  Heavy rain is likely to cause flash floods in some locations.  Typhoon Sinlaku could cause a storm surge of up to 13 feet (4 meters) along parts of the coasts of the southern Marianas.

Sinlaku Rapidly Intensifies to a Typhoon

Former Tropical Storm Sinlaku rapidly intensified to a typhoon southeast of Guam on Friday.  At 11:00 p.m. EDT on Friday the center of Typhoon Sinlaku was located at latitude 8.7°N and longitude 151.5°E which put the center about 575 miles (930 km) southeast of Guam.  Sinlaku was moving toward the north at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 972 mb.

Former Tropical Storm Sinlaku rapidly intensified to a typhoon on Friday.  The inner end of a rainband wrapped around the center of Sinlaku’s circulation.  A small eye appeared to be forming at the center of Typhoon Sinlaku.  Bands of showers and thunderstorms were revolving around the center of Sinlaku’s circulation.  Storms near the center of Sinlaku generated upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The size of the circulation around Typhoon Sinlaku increased on Friday as Sinlaku rapidly intensified.  Winds to typhoon force extended out 50 miles (80 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 185 miles (295 km) from the center of Typhoon Sinlaku.

Typhoon Sinlaku will move through an environment favorable for intensification during the next 24 hours.  Sinlaku will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the middle of an upper level ridge that is over the Western North Pacific Ocean. The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Sinlaku will intensify during the next 24 hours.  Sinlaku could continue to intensify rapidly.  Typhoon Sinlaku is likely to strengthen to the equivalent of a major hurricane during the weekend.

Typhoon Sinlaku will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean. The high pressure system will steer Sinlaku toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Sinlaku will move toward the southern Marianas.  Sinlaku will approach Guam in less than three days.

Typhoon Sinlaku will continue to produce gusty winds and locally heavy rain over Chuuk before it moves farther away on Saturday.  Heavy rain could cause flash floods in some locations.

Typhoon Sinlaku will be the equivalent of a major hurricane when it approaches Guam.  Sinlaku could bring very strong winds and locally heavy rain to Guam.  Heavy rain is likely to cause flash floods in some locations.

Tropical Storm Sinlaku Forms Southeast of the Marianas

Tropical Storm Sinlaku formed southeast of the Marianas on Thursday.  At 5:00 p.m. EDT on Thursday the center of Tropical Storm Sinlaku was located at latitude 8.4°N and longitude 151.5°E which put the center about 65 miles (105 km) north-northwest of Chuuk.  Sinlaku was moving toward the 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 994 mb.

A low pressure system over the Western North Pacific Ocean southeast of the Marianas strengthened on Thursday and the Japan Meteorological Agency designated the system as Tropical Storm Sinlaku.

The circulation around Tropical Storm Sinlaku exhibited more organization on Thursday afternoon.  More thunderstorms formed near the center of Sinlaku’s circulation.  More thunderstorms also developed in bands revolving around the center of Tropical Storm Sinlaku.  Storms near the center of Sinlaku began to generate 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 Tropical Storm Sinlaku was fairly symmetrical.  Winds to tropical storm force extended out 105 miles (165 km) from the center of Sinlaku’s circulation.

Tropical Storm Sinlaku will move through an environment favorable for intensification during the next 24 hours.  Sinlaku 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 ridge will produce easterly winds that will blow toward the top of Sinlaku’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Tropical Storm Sinlaku will intensify during the next 24 hours.  Sinlaku is likely to strengthen to a typhoon within 36 hours.

Tropical Storm Sinlaku will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm Sinlaku will move away from Chuuk,  Sinlaku could approach Guam in three or four days.

Tropical Storm Sinlaku will produce gusty winds and locally heavy rain over Chuuk before it moves farther away on Friday.  Heavy rain could cause flash floods in some locations.

Typhoon Kalmaegi Moves over the Sulu Sea

Typhoon Kalmaegi moved over the Sulu Sea on Tuesday.  At 4:00 a.m. EST on Tuesday the center of Typhoon Kalmaegi was located at latitude 10.5°N and longitude 121.3°E which put the center about 130 miles (210 km) east-southeast of Taytay, Philippines.  Kalmaegi was moving toward the west at 16 m.p.h. (26 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 985 mb.

Typhoon Kalmaegi weakened as it moved across the central Philippines on Monday.  An eye was no longer visible on satellite images.  Thunderstorms were still occurring near the center of Kalmaegi’s circulation.  Thunderstorms were also occurring in bands in the southern half of Typhoon Kalmaegi.  Bands in the northern half of Kalmaegi’s circulation contained fewer thunderstorms.  Storms near the center of Kalmaegi still generated upper level divergence that pumped mass away to the west of the typhoon.  However, there was more mass converging in the lower levels of the atmosphere than there was mass diverging in the upper levels.  So, the surface pressure was increasing.

The size of the circulation around Typhoon Kalmaegi decreases as Kalmaegi weakened.  Winds to typhoon force extended out 30 miles (50 km) from the center of Kalmaegi’s circulation.  Winds to tropical storm force extended out 110 miles (170 km) from the center of Typhoon Kalmaegi.

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 29°C.  It will move under the southern part of an upper level ridge over the Western North Pacific Ocean.  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.  Typhoon Kalmaegi could start to intensify again during the next 24 hours.

Typhoon Kalmaegi will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Kalmaegi toward the west-northwest during the next 24 hours.  On its anticipated track, Typhoon Kalmaegi will pass near northern Palawan in a few hours.  Kalmaegi will move over the South China Sea on Tuesday night.

Typhoon Kalmaegi will bring strong winds and locally heavy rain to northern Palawan and the Calamian Group of islands.  Heavy rain is likely to cause flash floods in some locations.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 32W formed south of the Marianas.  At 4:00 a.m. EST on Tuesday the center of Tropical Depression 32W was located at latitude 9.5°N and longitude 142.7°E which put the center about 285 miles (460 km) south-southwest of Guam.  The tropical depression was moving toward the west at 11 m.p.h. (17 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 1000 mb.  It is forecast to strengthen.

Typhoon Usagi Rapidly Intensifies to Equivalent of a Major Hurricane

Typhoon Usagi rapidly intensified to the equivalent of a major hurricane over the Western North Pacific Ocean east of Luzon on Wednesday.  At 10:00 a.m. EST on Wednesday the center of Typhoon Usagi was located at latitude 16.5°N and longitude 124.8°E which put the center about 485 miles (780 km) east-southeast of Aparri, Philippines.  Usagi was moving toward the west-northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 949 mb.

Typhoon Usagi rapidly intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale east of Luzon on Wednesday.  A small circular eye with a diameter of 5 miles (8 km) formed at the center of Usagi’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 revolved around the core of Typhoon Usagi.  Storms near the core of Usagi generated strong upper level divergence that pumped large quantities of mass away from the typhoon in all directions.  The removal of large amounts of mass caused the surface pressure to decrease rapidly.

The circulation around Typhoon Usagi was small.  Winds to typhoon force extended out 30 miles (50 km) from the center of Usagi’s circulation.  Winds to tropical storm force extended out 80 miles (130 km) from the center of Typhoon Usagi.

The Hurricane Intensity Index (HII) for Typhoon Usagi was 25.1.  The Hurricane Size Index (HSI) was 9.4 and the Hurricane Wind Intensity Size Index (HWISI) was 34.5.  Typhoon Usagi was similar in size to Hurricane Harvey when Harvey hit Texas in 2017.  Usagi was not as big as Harvey was.

Typhoon Usagi will move through an environment favorable for intensification during the next 24 hours.  Usagi will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the axis of an upper level ridge over the Western North Pacific Ocean.  The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear.  Typhoon Usagi could continue to intensify during the next 24 hours.  However, since the core of Usagi’s circulation is so small, the inner end of a rainband could wrap around the core.  If concentric eyewalls form, an eyewall replacement cycle would halt the intensification of Typhoon Usagi.

Typhoon Usagi will move around the southern side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Usagi toward the west-northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Usagi will move near northeast Luzon in 18 hours.

Typhoon Usagi will bring strong winds and heavy rain to northern Luzon.  Heavy rain could cause flash floods and mudslides in some locations.  Usagi could cause a storm surge of up to 13 feet ( 4 meters) on the coast of northeastern Luzon.  The area likely to be hit by Usagi was just hit by Typhoon Toraji a few days ago.  Typhoon Usagi will complicate recovery efforts in Luzon.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Toraji was approaching the coast of China east of Hong Kong, and Tropical Storm Man-yi was moving away from the Marianas.

At 10:00 a.m. EST on Wednesday the center of Tropical Storm Toraji was located at latitude 21.9°N and longitude 114.9°E which put the center about 65 miles (105 km) east-southeast of Hong Kong.  Toraji was moving toward the north at 14 m.p.h. (22 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 995 mb.

At 10:00 a.m. EST on Wednesday the center of Tropical Storm Man-yi was located at latitude 11.7°N and longitude 140.4°E which put the center about 280 miles (450 km) west-southwest of Guam.  Man-yi was moving toward the west-southwest at 16 m.p.h. (26 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.