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Sepat Weakens to a Tropical Depression

Former Tropical Storm Sepat weakened to a tropical depression over the Western North Pacific Ocean south of Japan on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Depression Sepat was located at latitude 32.4°N and longitude 139.5°E which put the center about 230 miles (370 km) south of Tokyo, Japan.  Sepat was moving toward the north-northwest 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 1005 mb.

Former Tropical Storm Sepat weakened to a tropical depression on Tuesday as it moved over the Western North Pacific Ocean south of Japan.  Many of the thunderstorms in Sepat’s circulation dissipated.  A few thunderstorms were still occurring in the southeastern quadrant of Tropical Depression Sepat.  Most of the bands revolving around the center of Sepat’s circulation consisted primarily of showers and lower clouds.

Tropical Depression Sepat will move through an environment that will be unfavorable for intensification during the next 24 hours.  Sepat will move over water where where the Sea Surface Temperatures are near 25°C.  It will move under the northern part of an upper level ridge south of Japan.  The upper level ridge will produce west-southwesterly winds that will blow toward the top of Sepat’s circulation.  Those winds will cause strong vertical wind shear.  The strong vertical wind shear and marginal Sea Surface Temperatures will cause Tropical Depression Sepat to continue to weaken during the next 24 hours.

Tropical Depression Sepat will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Sepat toward the north during the next 24 hours.  On its anticipated track, Tropical Depression Sepat will approach eastern Honshu in 12 hours.  The center of Sepat’s circulation is likely to pass just to the southeast of Tokyo.

Tropical Depression Sepat is likely to bring gusty winds and rain to the part of Honshu southeast of Tokyo.

Tropical Storm Sepat Moves Toward Honshu

Tropical Storm Sepat moved toward Honshu on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Sepat was located at latitude 29.7°N and longitude 140.7°E which put the center about 420 miles (680 km) south of Tokyo, Japan.  Sepat was moving toward the 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 1003 mb.

Tropical Storm Sepat strengthened a little on Monday morning, but Sepat was showing signs of weakening on Monday evening.  Thunderstorms were still occurring near the center of Tropical Storm Sepat.  Thunderstorms were also occurring bands revolving around the center of Sepat’s circulation.  Storms near the center of Sepat generated upper level divergence that pumped mass away from the tropical storm.  The removal of mass in the upper levels was balanced by the inflow of mass in the lower levels of Tropical Storm Sepat.  The balance of upper level divergence and inflow in the lower levels caused the surface pressure to remain steady.

The distribution of wind speeds in Tropical Storm Sepat was asymmetrical.  Winds to tropical storm force extended out 110 miles (175 km) in the eastern side of Sepat’s circulation.  The winds in the western side of Tropical Storm Sepat were blowing at less than tropical storm force.

Tropical Storm Sepat will move through an environment that will become unfavorable for intensification during the next 24 hours.  Sepat will move over water where where the Sea Surface Temperatures are near 26°C.  It will move under the northern part of an upper level low south of Japan.  The upper level low will produce northeasterly winds that will blow toward the top of Sepat’s circulation.  Those winds will cause moderate vertical wind shear.  The vertical wind shear  and marginal Sea Surface Temperatures will cause Tropical Storm Sepat to weaken during the next 24 hours.  Sepat is likely to weaken to a tropical depression on Tuesday.

Tropical Storm Sepat will move around the western end of a high pressure system over the Western North Pacific Ocean.  The high pressure system will steer Sepat toward the north-northwest during the next 24 hours.  On its anticipated track, Tropical Storm Sepat will continue to move toward Honshu.

Typhoon Krathon Intensifies to Equivalent of Cat. 4 Hurricane

Typhoon Krathon intensified to the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale on Monday as it passed just south of Taiwan.  At 5:00 p.m. EDT on Monday the center of Typhoon Krathon was located at latitude 20.7°N and longitude 119.9°E which put the center about 135 miles (220 km) south-southwest of Kaohsiung, Taiwan.  Krathon was moving toward the west at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h).  The minimum surface pressure was 927 mb.

Typhoon Krathon continued to intensify Monday.  It is now the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  A circular eye with a diameter of 30 miles (50 km) is present at the center of Krathon’s circulation.  The eye is surrounded by a ring of thunderstorms and the strongest winds are occurring in that ring of storms.  Numerous bands of showers and thunderstorms are revolving around the core of Typhoon Krathon.  Storms near the core generated strong upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Krathon is symmetrical.  Winds to typhoon force extend out 80 miles (130 km) from the center of Krathon’s circulation.  Winds to tropical storm force extend out 200 miles (320 km) from the center of Typhoon Krathon.

The Hurricane Intensity Index (HII) for Typhoon Krathon is 31.6.  The Hurricane Size Index (HSI) is 24.1 and the Hurricane Wind Intensity Size Index (HWISI) is 55.7.  Typhoon Krathon is similar in intensity to Hurricane Laura when Jeanne hit Louisiana in 2020.  Krathon is bigger than Laura was.

Typhoon Krathon will move through an environment favorable for intensification during the next 24 hours.  Krathon will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the axis of an upper level ridge south of Japan.  The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear.  Even though Typhoon Krathon will be in an environment favorable for intensification, Krathon may not intensify.  Images from the Taiwan Central Weather Agency’s radar indicate that concentric eyewalls may be forming at the center of Krathon’s circulation.  If concentric eyewalls do form, then an eyewall replacement cycle would cause Typhoon Krathon to weaken during the next 24 hours.

Typhoon Krathon will move around the southwestern part of a high pressure system south of Japan.  The high pressure system will steer Krathon slowly toward the northwest during the next 24 hours.  On its anticipated track, Typhoon Krathon will move southwest of Taiwan.  An upper level trough over southern China will start to steer Krathon toward the northeast on Wednesday.  The center of Krathon could make landfall on Taiwan near Kaohsiung.

Typhoon Krathon will be a large, powerful storm when it hits Taiwan.  Krathon will bring strong winds and heavy rain to Taiwan.  Heavy rain will cause flash floods in some locations.  Typhoon Krathon could also cause a storm surge of up to 13 feet (4 meters) on the coast of southwestern Taiwan.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Jebi strengthened south of Japan.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Jebi was located at latitude 31.7°N and longitude 141.3°E which put the center about 320 miles (520 km) south-southeast of Tokyo, Japan.  Jebi was moving toward the north at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 986 mb.

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 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.

 

Maria Intensifies to a Typhoon Southeast of Japan

Former Tropical Storm Maria intensified to a typhoon southeast of Japan on Thursday.  At 5:00 p.m. EDT on Thursday the center of Typhoon Maria was located at latitude 30.5°N and longitude 145.8°E which put the center about 505 miles (815 km) southeast of Tokyo, Japan.  Maria was moving toward the north at 14 m.p.h. (22 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 969 mb.

Former Tropical Storm Maria intensified to a typhoon over the Western North Pacific Ocean southeast of Japan on Thursday.  A small circular eye formed at the center of Maria’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 Maria.  Storm 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 Maria was very small.  Winds to typhoon force extended out 25 miles (40 km) in the eastern side of Maria’s circulation.  Winds to tropical storm force extended out 70 miles (110 km) from the center of Typhoon Maria.

Typhoon Maria will move through an environment favorable for intensification during the next 24 hours.  Maria will move over water where the Sea Surface Temperatures are near 30°C.  It will move under the southeastern 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, but the wind shear will not be enough to prevent intensification.  Tropical Storm Maria is likely to continue to intensify during the next 24 hours.

Typhoon 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, Typhoon Maria will move closer to eastern Japan.