Tag Archives: Ampil

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 Wukong Forms Southeast of Japan

Tropical Storm Wukong formed southeast of Japan on Monday.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Wukong was located at latitude 29.0°N and longitude 159.0°E which put it about 1370 miles (2210 km) east-southeast of Tokyo, Japan.  Wukong was moving toward the north at 24 m.p.h. (39 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and the were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 984 mb.

A cluster of thunderstorms developed southeast of Japan during the weekend and a low level center of circulation formed near the southwestern edge of the cluster of storms.  However, strong upper level winds blowing from the southwest kept blowing the top of the circulation northeast of the low level center and the system was unable to develop.  The upper level winds slowed on Monday and a band of showers and thunderstorms wrapped around the northern and western sides of the center of circulation.  The Japan Meteorological Agency designated the system as Tropical Storm Wukong.

The circulation of Tropical Storm Wukong organized quickly after the upper level winds weakened.   As mentioned above, a primary rainband wrapped around the northern and western sides of the center of circulation.  Storms in the primary rainband generated upper level divergence which was pumping mass away to the north of the tropical storm.  Several other bands of showers and thunderstorms developed in the eastern half of the circulation.  Bands south and west of the center consisted primarily of showers and lower clouds.

Tropical Storm Wukong will move through an environment favorable for intensification during the next day or so.  Wukong will move over water where the Sea Surface Temperature is near 27°C.  Wukong is moving along the eastern portion of an upper level trough.  The trough is producing southwesterly winds which are blowing toward the top of the circulation.  However, those winds weakened on Monday and they will not cause enough vertical wind shear to prevent further intensification.  Tropical Storm Wukong could strengthen into a typhoon during the next 24 to 36 hours.  Eventually, Wukong will move over cooler water and it will begin to weaken.

Tropical Storm Wukong is moving between an upper level trough to the west and an upper level ridge to the east.  The trough and ridge were combining to steer Wukong toward the north and a general northerly motion is expected to continue.  On its anticipated track Tropical Storm Wukong will stay west of the larger islands of Japan.  Wukong could approach the Kuril Islands in about three days.

Elsewhere over the Western North Pacific former Tropical Storm Ampil weakened to a tropical depression over land southeast of Beijing, China, Tropical Storm Son-tinh meandered near the coast of southeastern China and Tropical Depression 15W organized southwest of Iwo To, Japan.  At 5:00 p.m. EDT on Monday the center of Tropical Depression Ampil was located at latitude 38.8°N and longitude 117.6°E which put it about 110 miles (175 km) southeast of Beijing, China.  Ampil was moving toward the north-northwest at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 35 m.p.h. (55k km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 998 mb.  Tropical Depression Ampil was still dropping locally heavy rain over parts of eastern China.

At 5:00 p.m. EDT on Monday the center of Tropical Storm Son-tinh was located at latitude 21.2°N and longitude 109.0°E which put it about 40 miles (65 km) southeast of Beihai, China.  Son-tinh was moving toward the west-northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 996 mb.  Tropical Storm Son-tinh was dropping locally heavy rain over parts of southeastern China and Hainan Island.

At 5:00 p.m. EDT on Monday the center of Tropical Depression 15W was located at latitude 17.6°N and longitude 136.3°E which put it about 585 miles (945 km) southwest of Iwo To, Japan.  It was moving toward the north-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 998 mb.  The circulation of Tropical Depression 15W became more organized on Monday and it could eventually strengthen into a typhoon when it moves toward Iwo To later this week.

Tropical Storm Ampil Nears Landfall Southeast of Shanghai

Tropical Storm Ampil neared landfall on the coast of China southeast of Shanghai on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Ampil was located at latitude 31.0°N and longitude 122.3°E which put it about 60 miles (95 km) southeast of Shanghai, China.  Ampil was moving toward the west-northwest at 14 m.p.h. (22km/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 990 mb.

Tropical Storm Ampil moved steadily toward the coast of China on Saturday with little change of structure or intensity.  Drier air continued to circulate around the tropical storm and it limited the development of taller thunderstorms in much of Ampil.  The strongest thunderstorms were occurring in the inner portion of a band northwest of center of circulation.  The strongest winds were associated with those storms.  Bands around the rest of Tropical Storm Ampil consisted of showers and lower clouds.  Winds to tropical storm force extended out about 165 miles (270 km) from the center.

Tropical Storm Ampil will make landfall on the coast of China southeast of Shanghai in a few hours.  Ampil will cause gusty winds and the strong band of thunderstorms will drop locally heavy rain.  The heavy rain could cause flash floods in parts of eastern China.

Elsewhere the tropics became more active over the Western North Pacific Ocean on Saturday.  The remnants of former Tropical Storm Son-tinh were reorganizing west of Hainan Island over the Gulf of Tongking, Tropical Depression 13W moved east of Taiwan, and Tropical Depression 14W formed northwest of Wake Island and Tropical Depression 15W formed west of Guam.

At 11:00 p.m. EDT on Saturday the center of Tropical Depression Son-tinh was located at latitude 19.2°N and longitude 108.2°E which put it about 45 miles (75 km) west of Dongfeng, China.  Son-tinh was moving toward the east-southeast at 7 m.p.h. (11 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.

Former Tropical Storm Son-tinh completed a slow clockwise loop over Laos and Vietnam which during the past several days and it emerged back over the Gulf of Tongking on Saturday.  There was a distinct low level center of circulation.  Bands of showers and thunderstorms were circulating around the enter.  The rainbands were dropping heavy rain over Hainan Island and creating the potential for flash floods.

At 11:00 p.m. EDT on Saturday the center of Tropical Depression 13W was located at latitude 21.6°N and longitude 122.9°E which put it about 165 miles (265 km) south-southeast of Hualien, Taiwan.  It was moving toward the northwest at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 998 mb.

At 11:00 p.m. EDT on Saturday the center of Tropical Depression 14W was located at latitude 22.5°N and longitude 159.4°E which put it about 370 miles (600 km) east-southeast of Minami Tori Shima.  It was moving toward the north at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 998 mb.

At 11:00 p.m. EDT on Saturday the center of Tropical Depression 15W was located at latitude 13.2°N and longitude 138.1°E which put it about 225 miles (365 km) north-northwest of Ulithi.  It was moving toward the northwest at 15 m.p.h. (24 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 998 mb.

Tropical Storm Ampil Moves Over Okinawa

Tropical Storm Ampil moved over Okinawa on Friday night.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Ampil was located at latitude 27.3°N and longitude 127.4°E which put it about 25 miles (40 km) north-northwest of Okinawa.  Ampil was moving toward the northwest at 21 m.p.h. (34 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 990 mb.

Drier air continued to circulated around Tropical Storm Ampil on Friday and the drier air prevented Ampil from intensifying.  Several bands of stronger thunderstorms were occurring northeast of the center of circulation and the strongest winds were occurring in those bands.  The bands in other parts of Tropical Storm Ampil consisted primarily of the showers and low clouds.  There was a distinct low level center of circulation, but there were few thunderstorms near the center.  Winds to tropical storm force extended out about 160 miles (260 km) from the center.

Tropical Storm Ampil is unlikely to intensify significantly before it makes landfall in China.  Ampil will move over water where the Sea Surface Temperature is near 28°C.  So, there will be enough energy in the ocean to support intensification.  There is a chance for some intensification on Saturday, if more thunderstorms develop near the center of circulation.  However, the drier air will inhibit the formation of taller thunderstorms and that will limit possible intensification..

Tropical Storm Ampil will move south of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Ampil quickly toward the northwest.  On its anticipated track Tropical Storm Ampil will move quickly away from Okinawa and the Ryukyu Islands.  Ampil could approach the coast of China near Shanghai in about 24 hours.  Tropical Storm Ampil will bring gusty winds and locally heavy rain to the region of China around Shanghai.

Elsewhere over the Western North Pacific Ocean Tropical Depression 13W formed west of northern Luzon.  At 11:00 p.m. EDT on Friday the center of Tropical Depression 13W was located at latitude 18.0°N and longitude 118.9°E which put it about 140 miles (225 km) west of Laoag, Philippines.  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 998 mb.  The depression could bring locally heavy rain and cause flash floods over Luzon during the weekend.

Tropical Storm Ampil Moves Toward Okinawa

Tropical Storm Ampil moved toward Okinawa on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Ampil was located at latitude 23.3°N and longitude 130.6°E which put it about 320 miles (520 km) southeast of Okinawa.  Ampil was moving toward the north-northwest at 11 m.p.h. (17 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 Ampil strengthened on Thursday, although its appearance on satellite imagery was not particularly impressive.  There was a distinct low level center of circulation, but the most of the stronger thunderstorms were occurring in a rainband southwest of the center of circulation.  Bands in other parts of the tropical storm consisted primarily of showers and low clouds.  It appeared that some drier air could have wrapped around the southern and eastern sides of the circulation.  The drier air may have inhibited the development of taller thunderstorms in those parts of Tropical Storm Ampil.  The circulation was fairly large and winds to tropical storm force extended out about 185 miles (295 km) from the center of circulation.

Tropical Storm Ampil will move through an environment that could support further intensification during the next day or two.  Ampil will move over water where the Sea Surface Temperature is near 29°C.  It will be near the eastern end of an upper level low, but Tropical Storm Ampil will move under a zone where the upper level winds will not be too strong.  There will be some vertical wind shear, but the shear will not be strong enough to prevent intensification.  The main factor that could inhibit intensification will be the drier air already around the circulation.  If the strong rainband in the southwestern part of Tropical Storm Ampil wraps around the center of circulation, it could prevent the drier air from affecting the core of the tropical storm.  If that happens, the Tropical Storm Ampil would be likely to intensify and it could become a typhoon.  However, if the drier air works its way into the center of circulation, then Ampil will not intensify.

Tropical Storm Ampil will move southwest of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Ampil in a northwesterly direction during the next 24 to 48 hours.  On its anticipated track Tropical Storm Ampil could be near Okinawa and the Ryukyu Islands in less than 24 hours.  Ampil could reach the east coast of China south of Shanghai in about two days.  Tropical Storm Ampil will bring gusty winds to the Ryukyu Islands later on Friday.  Ampil could bring gusty winds and locally heavy rain to parts of eastern China during the weekend.

Tropical Storm Son-tinh Makes Landfall in Vietnam, Ampil Forms South of Okinawa

Tropical Storm Son-tinh made landfall in Vietnam on Wednesday while Tropical Storm Ampil formed south of Okinawa.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Son-tinh was located at latitude 19.1°N and longitude 105.5°E which put it about 30 miles (50 km) north-northwest of Vinh, Vietnam.  Son-tinh was moving toward the west 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 990 mb.

Tropical Storm Son-tinh strengthened on Wednesday after it moved away from Hainan Island.  A primary rainband wrapped around the western and southern side of the center of circulation and the inner end of the band began to evolve into a partial eyewall.  Thunderstorms in the core of Son-tinh generated upper level divergence which pumped away mass.  The removal of mass allowed the surface pressure to decrease.  A stronger pressure gradient force produced higher wind speeds.

Tropical Storm Son-tinh moved south of a ridge in the upper and middle troposphere.  The ridge steered Son-tinh steadily toward the west and the tropical storm made landfall just north of Vinh, Vietnam late on Wednesday.  Tropical Storm Son-tinh brought gusty winds and locally heavy rain to the coast of northern Vietnam around Vinh.  Son-tinh was also dropping locally heavy rain over portions of northern Vietnam and flash flooding could occur in some locations.

Tropical Storm Son-tinh will continue to move westward over northern Vietnam and northern Laos.  Son-tinh will weaken as the circulation moves inland.  It will continue to drop locally heavy rain and flash floods could occur in parts of northern Vietnam and northern Laos during the next several days.

The organization of former Tropical Depression 12W improved on Wednesday and the Japan Meteorological Agency designated the system as Tropical Storm Ampil.  At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Ampil was located at latitude 19.9°N and longitude 129.6°E which put it about 480 miles (775 km) south-southeast of Okinawa.  Ampil was moving toward the east-northeast at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 996 mb.

The circulation of Tropical Storm Ampil was not particularly well organized.  It exhibited characteristics of a hybrid low pressure system.  There was an upper low northwest of the low level circulation.  The upper low was causing strong southwesterly winds which were blowing across the top of the lower level circulation.  Those winds were causing significant vertical wind shear and they were tilting the circulation strongly toward the northeast.  The strongest bands of showers and thunderstorms were occurring south and west of the low level circulation.  Bands north and west of the center consisted primarily of showers and lower clouds.

The upper low will gradually move toward the west.  As the low moves westward, the vertical wind shear over Tropical Storm Ampil will start to decrease.  Ampil will move over water where the Sea Surface Temperature is near 29°C.  So, when the vertical wind shear decreases, then Tropical Storm Ampil will likely intensify.  Ampil could eventually strengthen into a typhoon in two or three days.

The upper low will initially will steer Tropical Storm Ampil toward the northeast.  When the upper low moves farther to the west on Thursday, then Ampil will move toward the north.  On its anticipated track the center of Tropical Storm Ampil could be near Okinawa and the Ryukyu Islands in two or three days.