Category Archives: Western North Pacific

Western Pacific Typhoons and Tropical Storms

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.

 

Tropical Storm Ampil Forms South of Japan

Tropical Storm Ampil formed over the Western North Pacific Ocean south of Japan on Monday afternoon.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Ampil was located at latitude 24.7°N and longitude 138.1°E which put the center about 760 miles (1225 km) south of Tokyo, Japan.  Ampil was moving toward the northeast at 12 m.p.h. (19 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.

A low pressure system over the Western North Pacific Ocean south of Japan strengthened on Monday afternoon and the Japan Meteorological Agency designated the system as Tropical Storm Ampil.  More thunderstorms developed near the center of Ampil’s circulation.  The inner end of a rainband wrapped part of the way around the center of Tropical Storm Ampil.  Other bands of showers and thunderstorms were revolving around the center of circulation.  Storms near the center generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass caused the surface pressure to decrease.

Tropical Storm 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 under a small upper level ridge that is in between and upper level low southwest of Japan and an upper level low east of Japan.  The upper level winds are weak in the small ridge and there will be little vertical wind shear.  Tropical Storm Ampil will intensify during the next 24 hours.  Ampil could intensify rapidly at times.  Tropical Storm Ampil is likely to strengthen to a typhoon within 36 hours.

Tropical Storm 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, Tropical Storm Ampil will move closer to central Honshu.

Elsewhere over the Western North Pacific Ocean, former Tropical Storm Maria weakened to a tropical depression over the Sea of Japan, and a subtropical cyclone east of Japan made a transition to Tropical Storm Son-tinh.

At 5:00 p.m. EDT on Monday the center of Tropical Depression Maria was located at latitude 41.0°N and longitude 138.7°E which put the center about 100 miles (160 km) west-southwest of Aomori, Japan.  Maria was moving toward the north-northwest at 9 m.p.h. (15 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 999 mb.

At 5:00 p.m. EDT on Monday the center of Tropical Storm Son-tinh was located at latitude 3.7°N and longitude 149.0°E which put the center about 560 miles (905 km) east of Tokyo, Japan. Son-tinh was moving toward the northwest at 15 m.p.h. (24 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 993 mb.

 

Tropical Storm Maria Brings Wind and Rain to Northern Honshu

Tropical Storm Maria brought wind and rain to northern Honshu on Sunday night.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Maria was located at latitude 39.4°N and longitude 141.2°E which put the center about 10 miles (15 km) east of Hanamaki, Japan.  Maria was moving toward the northwest at 14 m.p.h. (22 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 984 mb.

Tropical Storm Maria brought wind and rain to northern Honshu on Sunday night.  The center of Maria’s circulation made landfall near Kesennuma in Miyagi prefecture.  Tropical Storm Maria exhibited more organization as it neared landfall in northern Honshu.  A small circular eye appeared on both satellite images and radar images from the Japan Meteorological Agency.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of thunderstorms were revolving around the center of Maria’s circulation.

The circulation around Tropical Storm Maria was fairly symmetrical at the time of landfall.  Winds to tropical storm force extended out 120 miles (195 km) from the center of Maria’s circulation.

Tropical Storm Maria will move around the western end of a high pressure system over the North Pacific Ocean.  The high pressure system will steer Maria toward the northwest during the next 24 hours.  On its anticipated track, Tropical Storm Maria will move over Iwate and Akita prefectures.  Maria could move over the Sea of Japan in 12 hours.

Tropical Storm Maria will weaken steadily as it moves across northern Honshu.  Maria will continue to bring gusty winds and locally heavy rain to parts of Iwate and Akita prefectures during the next 12 to 24 hours.  Heavy rain could cause flash floods in some locations.

Tropical Storm Maria Moves Toward Northern Honshu

Tropical Storm Maria moved toward northern Honshu on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Maria was located at latitude 37.7°N and longitude 144.4°E which put the center about 235 miles (355 km) east-southeast of Sendai, Japan.  Maria was moving toward the north-northwest at 9 m.p.h. (15 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 981 mb.

Tropical Storm Maria exhibited more organization on Saturday night as it moved closer to northern Honshu.  The inner end of a rainband wrapped around the center of Maria’s circulation.  A small circular eye appeared intermittently on satellite images.  Bands of showers and thunderstorms revolved around the center of Tropical Storm Maria.  Storms near the center generated upper level divergence that pumped mass away from the tropical storm.

The distribution of wind speeds around Tropical Storm Maria was more symmetrical on Saturday.  Winds to tropical storm force extended out 155 miles (250 km) from the center to Maria’s circulation.

Tropical Storm Maria will move through an environment somewhat favorable for intensification during the next 18 hours.  Maria will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the eastern part of an upper level ridge over Japan.  The upper level winds are weak in that part of the ridge and there will be little vertical wind shear.  Tropical Storm Maria could intensify during the next 18 hours, but it is more likely that Maria will maintain its current intensity.

Tropical Storm Maria will move around the southwestern part of a high pressure system over the North Pacific Ocean.  The high pressure system will steer Maria toward the west-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Maria will approach the coast of northern Honshu in less than 24 hours.

Tropical Storm Maria will bring strong winds and locally heavy rain to northern Honshu.  Heavy rain could cause flash floods in some locations.

Tropical Storm Maria Spins East of Japan

Tropical Storm Maria was spinning east of Japan on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Maria was located at latitude 34.5°N and longitude 145.8°E which put the center about 400 miles (645 km) east of Tokyo, Japan.  Maria was moving toward the north at 15 m.p.h. (24 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 987 mb.

Former Typhoon Maria weakened back to a tropical storm over the Western North Pacific Ocean east of Japan on Friday.  The wind in the western part of Maria appeared to pull drier air around the southern side of Maria’s circulation.  The drier caused many of the thunderstorms in southern side of Tropical Storm Maria to dissipate.  Bands in the southern half of Maria’s circulation consisted primarily of showers and lower clouds.  Thunderstorms were still occurring in bands in the northern half of Tropical Storm Maria.

The distribution of wind speeds in Tropical Storm Maria was asymmetrical.  Winds to tropical storm force extended out 140 miles (225 km) in the eastern side of Maria’s circulation.  Winds to tropical storm force only extended out 85 miles (135 km) in the western side of Tropical Storm Maria.

Tropical Storm Maria will move through an environment somewhat favorable for intensification during the next 24 hours.  Maria will move over water where the Sea Surface Temperatures are near 28°C.  It will move under the eastern part of an upper level trough over Japan.  The upper level trough will produce southwesterly winds that will blow toward the top of Maria’s circulation.  Those winds will cause some vertical wind shear.  The vertical wind shear and the drier air in Tropical Storm Maria will inhibit intensification.  Tropical Storm Maria could intensify during the next 24 hours even with the effects of the wind shear and drier air.

Tropical Storm Maria will move around the western side of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Maria toward the north during the next 24 hours.  On its anticipated track, Tropical Storm Maria will move closer to eastern Japan.  Maria could start to move toward Honshu during the weekend.