Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

Typhoon Shanshan Strengthens to Equivalent of a Cat. 4 Hurricane

Typhoon Shanshan strengthened to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale over the northern Ryukyu Islands on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Typhoon Shanshan was located at latitude 29.2°N and longitude 130.0°E which put the center about 90 miles (145 km) south-southwest of Kamiyaku, Japan.  Shanshan was moving toward the north-northwest at 5 m.p.h. (8 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 932 mb.

Typhoon Shanshan intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Tuesday.  A circular eye with a diameter of 30 miles (50 km) was at the center of Shanshan’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 core of Typhoon Shanshan.  Storms near the core generated strong upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The circulation around Typhoon Shanshan was symmetrical.  Winds to typhoon force extended out 30 miles (50 km) from the center of Shanshan’s circulation.  Winds to tropical storm force extended out 145 miles (230 km) from the center of Typhoon Shanshan.

The Hurricane Intensity Index (HII) for Typhoon Shanshan was 25.1.  The Hurricane Size Index (HSI) was 12.1 and the Hurricane Wind Intensity Size Index (HWISI) was 37.2.  Typhoon Shanshan was similar in size and intensity to Hurricane Harvey when Harvey hit Texas in 2017.

Typhoon Shanshan will move through an environment that will be favorable for intensification during the next 24 hours.  Shanshan will move over water where the Sea Surface Temperatures are near 29°C.  It will through a region where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Shanshan could intensify during the next 24 hours.

Typhoon Shanshan will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Shanshan toward the north-northwest during the next 24 hours.  On its anticipated track, Typhoon Shanshan will toward western Kyushu.  Shanshan could approach western Kyushu in 36 hours.

Typhoon Shanshan will continue to produce strong winds and heavy rain in the northern Ryukyu Islands.  The eastern side of the eyewall of Shanshan will move near Yakushima.  Shanshan will be capable of causing severe damage.  Heavy rain is likely to cause flash floods in some locations.  Typhoon Shanshan will also cause a storm surge in the northern Ryukyu Islands where the wind blows the water toward the shore.

 

Typhoon Shanshan Intensifies to the Equivalent of a Major Hurricane

Typhoon Shanshan intensified to the equivalent of a major hurricane near the northern Ryukyu Islands on Monday evening.  At 11:00 p.m. EDT on Monday the center of Typhoon Shanshan was located at latitude 28.3°N and longitude 130.6°E which put the center about 75 miles (120 km) east of Naze, Japan.  Shanshan was moving toward the northwest at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 943 mb.

Typhoon Shanshan intensified to the equivalent of a major hurricane on Monday evening as it moved slowly near the northern Ryukyu Islands.  A small circular eye with a diameter of 12 miles (19 km) was at the center of Shanshan’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 core of Typhoon Shanshan.  Storms near the core generated strong upper level divergence that pumped mass away from the typhoon.  The removal of mass caused the surface pressure to decrease.

The circulation around Typhoon Shanshan was symmetrical.  Winds to typhoon force extended out 40 miles (65 km) from the center of Shanshan’s circulation.  Winds to tropical storm force extended out 125 miles (200 km) from the center of Typhoon Shanshan.

The Hurricane Intensity Index (HII) for Typhoon Shanshan was 22.1.  The Hurricane Size Index (HSI) was 13.7 and the Hurricane Wind Intensity Size Index (HWISI) was 35.8.  Typhoon Shanshan was similar in size to Hurricane Delta when Delta hit southwest Louisiana in 2020.  Shanshan was stronger than Delta was.

Typhoon Shanshan will move through an environment that will be favorable for intensification during the next 24 hours. Shanshan will move over water where the Sea Surface Temperatures are near 29°C.  It will through a region where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Shanshan is likely to continue to intensify during the next 24 hours.

Typhoon Shanshan will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Shanshan slowly toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Shanshan will move over the northern Ryukyu Islands.  Shanshan could approach southwestern Japan in 48 hours. Shanshan could be a strong typhoon when it approaches Kyushu.

Typhoon Shanshan will bring strong winds and heavy rain to the northern Ryukyu Islands.  Shanshan will be capable of causing major damage.  Heavy rain is likely to cause flash floods in some locations.  Typhoon Shanshan will also cause a storm surge on the northern Ryukyu Islands where the wind blows the water toward the shore.

Typhoon Shanshan Continues to Strengthen

Typhoon Shanshan continues to strengthen over the Western North Pacific Ocean south of Japan on Sunday.  At 11:00 p.m. EDT on Sunday the center of Typhoon Shanshan was located at latitude 27.3°N and longitude 133.5°E which put the center about 350 miles (565 km) south-southeast of Kagoshima, Japan.  Shanshan was moving toward the west-northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 968 mb.

Typhoon Shanshan strengthened gradually on Sunday as it moved over the Western North Pacific Ocean south of Japan.  A large circular eye was present at the center of Shanshan’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 core of Typhoon Shanshan.  Storms near the core of Shanshan’s circulation generated more upper level divergence that pumped mass away from the typhoon.  The removal of more mass caused the surface pressure to decrease.

The size of the circulation around typhoon Shanshan increased slightly on Sunday.  Winds to typhoon force extended out 35 miles (55 km) from the center of Shanshan’s circulation.  Winds to tropical storm force extended out 145 miles (230 km) from the center of Typhoon Shanshan.

The Hurricane Intensity Index (HII) for Typhoon Shanshan was 13.9.  The Hurricane Size Index (HSI) was 11.7 and the Hurricane Wind Intensity Size Index (HWISI) was 25.6.

Typhoon Shanshan will move through an environment that will be favorable for intensification during the next 24 hours.  Shanshan will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the northern periphery of an upper level low south of Japan.  The upper level low will produce easterly winds that will blow toward the top of Shanshan’s circulation.  Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification.  Typhoon Shanshan will intensify during the next 24 hours.

Typhoon Shanshan will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Shanshan toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Shanshan will move closer to Kyushu and Shikoku.  Shanshan could approach southwestern Japan in 48 hours.  Shanshan could be a strong typhoon when it approaches Japan.

 

Typhoon Shanshan Passes West of Iwo To

The center of Typhoon Shanshan passed west of Iwo To on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Typhoon Shanshan was located at latitude 25.4°N and longitude 138.4°E which put the center about 150 miles (240 km) west of Iwo To.  Shanshan was moving toward the northwest at 15 m.p.h. (24 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 974 mb.

Typhoon Shanshan maintained its intensity on Saturday as it moved over the Western North Pacific Ocean west of Iwo To.  Shanshan moved under the eastern side of an upper level low south of Japan.  The upper level low produced southerly winds that blew toward the top of Shanshan’s circulation.  Those winds caused moderate vertical wind shear, and the wind shear prevented intensification of Typhoon Shanshan.

The vertical wind shear also affected the structure of Typhoon Shanshan.  A small circular eye was present at the center of Shanshan’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 occurring in bands in the northern side of Typhoon Shanshan.  Bands in the southern part of Shanshan’s circulation consisted primarily of showers and lower clouds.  Storms near the center of Shanshan generated upper level divergence that pumped mass away to the north of the typhoon.  The removal of mass in the upper levels was balanced by the inflow of mass in the lower levels of the atmosphere.  The balance of the outflow and inflow of mass caused the surface pressure to remain steady on Saturday.

Winds to typhoon force extended out 35 miles (55 km) from the center of Typhoon Shanshan.  Winds to tropical storm force extended out 125 miles (200 km) from the center of Shanshan’s circulation.

Typhoon Shanshan will move through an environment that will become more favorable for intensification during the next 24 hours.  Shanshan will move over water where the Sea Surface Temperatures are near 29°C.  It will move farther away from the upper level low south of Japan.  The upper level low will still produce southerly winds that will blow toward the top of Shanshan’s circulation.  However, there will be less vertical wind shear on Sunday.  Typhoon Shanshan is likely to intensify during the next 24 hours.

Typhoon Shanshan will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Shanshan toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Shanshan will move closer to Kyushu and Shikoku.  Shanshan could approach southwestern Japan in 48 hours.  Shanshan could be a strong typhoon when it approaches Japan.

 

Shanshan Strengthens to a Typhoon

Former Tropical Storm Shanshan strengthened to a typhoon over the Western North Pacific Ocean south of Iwo To.  At 11:00 p.m. EDT on Friday the center of Typhoon Shanshan was located at latitude 20.5°N and longitude 141.2°E which put the center about 330 miles (535 km) south of Iwo To.  Shanshan was moving toward the north at 14 m.p.h. (22 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 974 mb.

Former Tropical Storm Shanshan strengthened to a typhoon south of Iwo To on Friday.  The inner end of a raindband wrapped around the center of Shanshan’s circulation.  A circular eye formed at the center of Typhoon Shanshan.  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 Shanshan’s circulation.  Storms near the center of Shanshan generated more upper level divergence that pumped mass away from the typhoon.  The removal of more mass caused the surface pressure to decrease.

Winds to typhoon force extended out 30 miles (50 km) from the center of Typhoon Shanshan.  Winds to tropical storm force extended out 115 miles (185 km) from the center of Shanshan’s circulation.

Typhoon Shanshan will move through an environment favorable for intensification during the next 24 hours.  Shanshan will move over water where the Sea Surface Temperatures are near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Shanshan will intensify during the next 24 hours.

Typhoon Shanshan will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Shanshan toward the north-northwest during the next 24 hours.  On its anticipated track, the center of Typhoon Shanshan will be near Iwo To in 24 hours.  Shanshan could approach central Japan in 72 hours.

 

Tropical Storm Shanshan Forms South of Iwo To

Tropical Storm Shanshan formed over the Western North Pacific Ocean south of Iwo To on Wednesday evening.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Shanshan was located at latitude 17.2°N and longitude 141.5°E which put the center about 505 miles (810 km) south of Iwo To.  Shanshan was moving toward the west 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 1001 mb.

A low pressure system over the Western North Pacific Ocean south of Iwo To strengthened on Wednesday evening and the Japan Meteorological Agency designated the system as Tropical Storm Shanshan.  The circulation around Tropical Storm Shanshan exhibited more organization on satellite images, but the distribution of thunderstorms was asymmetrical.  Thunderstorms were occurring in bands in the eastern side of Shanshan’s circulation.  Bands in the western side of Tropical Storm Shanshan consisted primarily of showers and lower clouds.  Storms near the center of Shanshan began to generate upper level divergence that pumped mass away from the tropical storm.

The circulation around Tropical Storm Shanshan was small.  Winds to tropical storm force extended out 45 miles (75 km) from the center of Shanshan’s circulation.

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

Tropical Storm Shanshan will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Shanshan toward the north-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Shanshan will move closer to Iwo To.  Shanshan could approach Japan in five days.

Typhoon Ampil Moves Quickly Away from Japan

Typhoon Ampil moved quickly away from Japan on Saturday.  At 5:00 p.m. EDT on Saturday the center of Typhoon Ampil was located at latitude 39.1°N and longitude 151.1°E which put the center about 620 miles (1000 km) east-northeast of Tokyo, Japan.  Ampil was moving toward the east-northeast at 24 m.p.h. (39 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 973 mb.

Typhoon Ampil weakened steadily as it moved quickly away from Japan on Saturday.  Ampil moved over water where the Sea Surface Temperatures were cooler.  In addition, the upper level westerly winds in the middle latitudes caused strong vertical wind shear.  The cooler water and wind shear caused Typhoon Ampil to weaken.  The circulation around the western side of Ampil’s circulation also pulled drier air into the southern and western parts of the typhoon.

Cooler water, strong vertical wind shear, and drier air affected the structure of Typhoon Ampil.  A large circular eye was still present at the center of Ampil’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 still occurring in bands in the eastern and northern parts of Typhoon Ampil.  Bands in the southern and western parts of Ampil’s circulation consisted primarily of showers and lower clouds.

There was still a large circulation around Typhoon Ampil.  Winds to typhoon force extended out 25 miles (40 km) from the center of Ampil’s circulation.  Winds to tropical storm force extended out 165 miles (265 km) from the center of Typhoon Ampil.

Typhoon Ampil will move through an environment that will be unfavorable for intensification during the next 24 hours.  Ampil will move over water where the Sea Surface Temperatures are near 23°C.  It will move under the upper level westerly winds in the middle latitudes. Those westerly winds will cause strong vertical wind shear.  The cooler water and strong vertical wind shear will cause Typhoon Ampil to continue to weaken during the next 24 hours.  The cooler water and strong wind shear will also cause Ampil to make a transition to a strong extratropical cyclone during the next 48 hours.

The westerly winds in the middle latitudes will steer Typhoon Ampil toward the east-northeast during the next 24 hours.  On its anticipated track, Typhoon Ampil will move farther away from Japan.

 

Typhoon Ampil Passes East of Tokyo

Typhoon Ampil passed east of Tokyo on Friday morning.  At 11:00 a.m. EDT on Friday the center of Typhoon Ampil was located at latitude 35.4°N and longitude 142.5°E which put the center about 130 miles (210 km) east of Tokyo, Japan.  Ampil was moving toward the northeast at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 944 mb.

Typhoon Ampil was the equivalent of a major hurricane when it passed east of Tokyo on Friday morning.  Bands in the western part of Ampil’s circulation brought gusty winds and locally heavy rain to coastal parts of central Honshu.  The airport at Narita reported a sustained wind speed of 32 m.p.h. (52 km/h) and a wind gust of 52 m.p.h. (83 km/h).

A large circular eye was present at the center of Typhoon Ampil.  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 Ampil’s circulation.  Storms near the core generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels of the atmosphere was almost in balance with the inflow of mass in the lower atmosphere.

The circulation around Typhoon Ampil was large. Winds to typhoon force extended out 50 miles (80 km) from the center of Ampil’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Typhoon Ampil.

The Hurricane Intensity Index (HII) for Typhoon Ampil was 22.1.  The Hurricane Size Index (HSI) was 17.0 and the Hurricane Wind Intensity Size Index (HWISI) was 39.1.  Typhoon Ampil was similar in intensity to Hurricane Delta when Delta hit Louisiana in 2020.  Ampil is larger than Delta was.

Typhoon Ampil will move through an environment that will become less favorable for intensification during the next 24 hours.  Ampil will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the upper level westerly winds in the middle latitudes.  Those westerly winds will cause the vertical wind shear to increase.  The increase in vertical wind shear will cause Typhoon Ampil to start to weaken during the next 24 hours.

The westerly winds in the middle latitudes will steer Typhoon Ampil toward the east during the next 24 hours.  On its anticipated track, Typhoon Ampil will move away from Japan.

Typhoon Ampil Strengthens to Equivalent of a Major Hurricane

Typhoon Ampil strengthened to the equivalent of a major hurricane south of Tokyo on Thursday afternoon.  At 5:00 p.m. EDT on Thursday the center of Typhoon Ampil was located at latitude 33.0°N and longitude 140.9°E which put the center about 205 miles (330 km) south-southeast of Tokyo, Japan.  Ampil was moving toward the north at 12 m.p.h. (19 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. (230 km/h).  The minimum surface pressure was 951 mb.

A large circular eye was present at the center of Typhoon Ampil.  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 Ampil’s circulation.  Storms near the core 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 Ampil was large.  Winds to typhoon force extended out 50 miles (80 km) from the center of Ampil’s circulation.  Winds to tropical storm force extended out 180 miles (290 km) from the center of Typhoon Ampil.

The Hurricane Intensity Index (HII) for Typhoon Ampil was 20.6.  The Hurricane Size Index (HSI) was 17.1 and the Hurricane Wind Intensity Size Index (HWISI) was 37.7.  Typhoon Ampil was similar in intensity to Hurricane Delta when Delta hit Louisiana in 2020.  Ampil is bigger than Delta was.

Typhoon Ampil will move through an environment favorable for intensification during the next 12 hours.  Ampil will move over water where the Sea Surface Temperatures are near 30°C. It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Ampil could continue to intensify during the next 12 hours.  Ampil Will move into an area where there are stronger westerly winds in the upper level within 24 hours.  Those stronger winds will cause the vertical wind shear to increase.  Typhoon Ampil will start to weaken when the wind shear increases.

Typhoon Ampil will move around the western side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Ampil toward the north during the next 12 hours.  On its anticipated track, Typhoon Ampil will be near the coast of central Honshu just to the southeast of Tokyo in 12 hours.  Ampil will start to move toward the east when it reaches the westerly winds in the upper levels.

Typhoon Ampil will bring strong winds and locally heavy rain to the coast of central Honshu south and east of Tokyo.  Strong winds will be capable of causing serious damage.  Heavy rain could cause flash floods in some locations.

 

Ampil Strengthens to a Typhoon South of Japan

Former Tropical Storm Ampil strengthened to a typhoon south of Japan on Wednesday morning.  At 11:00 a.m. EDT on Wednesday the center of Typhoon Ampil was located at latitude 28.0°N and longitude 141.1°E which put the center about 540 miles (870 km) south of Tokyo, Japan.  Ampil was moving toward the north-northeast at 9 m.p.h. (15 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 974 mb.

Former Tropical Storm Ampil strengthened to a typhoon south of Japan on Wednesday morning.  A small circular eye formed at the center of Typhoon Ampil’s circulation.  A ring of thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the center of Typhoon Ampil.  Storms near the center generated upper level divergence that pumped mass away from the typhoon.

Winds to typhoon force extended out 45 miles (75 km) from the center of Ampil’s circulation.  Winds to tropical storm force extended out 185 miles (295 km) from the center of Typhoon Ampil.

Typhoon Ampil will move through an environment favorable for intensification during the next 24 hours.  Ampil will move over water where the Sea Surface Temperatures are near 30°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Ampil will intensify during the next 24 hours.  Ampil could intensify rapidly at times.  Typhoon Ampil could strengthen to the equivalent of a major hurricane within 36 hours.

Typhoon Ampil will move around the western side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Ampil toward the north during the next 24 hours.  On its anticipated track, Typhoon Ampil will be near the coast of central Honshu in 48 hours.