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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.

Tropical Storm Son-tinh Moves Across Hainan Island

Tropical Storm Son-tinh moved across Hainan Island on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Son-tinh was located at latitude 18.9°N and longitude 108.5°E which put it about 15 miles (25 km) southwest of Dongfang, China.  Son-tinh was moving toward the west at 21 m.p.h. (34 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 center of Tropical Storm Son-tinh moved east to west across the southern half of Hainan Island on Tuesday.  In spite of moving over the island, the circulation of Tropical Storm Son-tinh retained its organization.  There was still a distinct low level center of circulation.  A primary rainband wrapped around the southern and eastern portions of the center.  Additional bands of showers and thunderstorms were revolving around the core of Son-tinh.  The strongest rainbands were in the western half of the tropical storm.  The circulation of Tropical Storm Son-tinh remains small.  Winds to tropical storm force only extend out about 70 miles (110 km) from the center of circulation.

Tropical Storm Son-tinh will move through an environment somewhat favorable for intensification during the next 12 hours.  Son-tinh will move over water where the Sea Surface Temperature is near 30°C.  It will move south of an upper level ridge.  The ridge will produce northeasterly winds which will blow toward the top of the circulation.  Those winds will create moderate vertical wind shear, but the shear will not be strong enough to prevent intensification.  Tropical Storm Son-tinh could strengthen after it moves west of Hainan Island and the center of circulation moves back over water.  Son-tinh is likely to reach the coast of Vietnam in 12 to 18 hours and it will weaken after landfall.

The ridge north of Son-tinh steered the tropical storm quickly toward the west on Tuesday.  It will continue to steer Tropical Storm Son-tinh in a general westerly direction on Wednesday.  On its anticipated track Tropical Storm Son-tinh will move steadily west of Hainan Island.  Locally heavy rain and gusty winds should gradually diminish there on Wednesday.  Son-tinh is likely to make landfall on the coast of Vietnam near Vinh in 12 to 18 hours and then move across Vietnam toward Laos.  Tropical Storm Son-tinh will bring gusty winds and locally heavy rain, but its impact will be lessened because of the small size of the circulation.  The heavy rain could cause flooding in isolated locations.

Elsewhere over the Western North Pacific Ocean, Tropical Depression 12W formed east of Luzon.  At 11:00 p.m. EDT on Tuesday the center of Tropical Depression 12W was located at latitude 18.9°N and longitude 126.1°E which put it about 545 miles (875 km) south of Okinawa.  It was moving toward the west at 12 m.p.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.

Typhoon Nesat Causes Heavy Rain, Floods in Taiwan

Typhoon Nesat caused heavy rain and floods in parts of Taiwan when it moved over the island.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Nesat was located at latitude 26.2°N and longitude 118.9°E which put it near Fuzhou, China.  Nesat was moving toward the northwest at 13 m.p.h. (21 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 977 mb.

The core of Typhoon Nesat moved over northern Taiwan earlier today and the center passed close to Taipei.  The typhoon brought strong winds and heavy rain to parts of northern and eastern Taiwan.  The rainfall was heavy enough in some locations to cause flash flooding.  Nesat weakened to a tropical storm when the center passed over Taiwan.

Tropical Storm Nesat moved quickly across the Taiwan Strait and it made another landfall on the east coast of China near Fuzhou.  Nesat produced gusty winds and locally heavy rain near the coast.  Heavy rain will continue to fall over eastern China as Tropical Storm Nesat moves farther inland and the rain could result in flooding in some locations.

Parts of Taiwan could receive additional heavy rain on Sunday when Tropical Storm Haitang approaches the southern part of the island.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Haitang was located at latitude 20.8°N and longitude 119.7°E which put it about 370 miles (595 km) south-southwest of Taipei, Taiwan.  Haitang was moving toward the east-northeast at at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 997 mb.

The distribution of rain in Tropical Storm Haitang is very asymmetrical.  Almost all of the showers and thunderstorms are located south of the center of circulation.  However, there is a fairly large area of heavy rain in the southern half of the circulation of Haitang.  Tropical Storm Haitang is currently moving toward the east-northeast, but it is forecast to turn toward the north in a trough of low pressure left behind in the wake of Tropical Storm Nesat.  On its anticipated track Haitang, could make landfall in southwestern Taiwan near Kaohsiung in about 12 hours.  When the heavy rain in Haitang reaches Taiwan, it could exacerbate the flooding caused by Nesat.

Elsewhere over the Western North Pacific the center of Tropical Storm Noru passed just east of Iwo To.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Noru was located at latitude 23.5°N and longitude 141.4°E which put it about 80 miles (130 km) south-southeast of Iwo To.  Noru was moving toward the south-southwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 978 mb.

Tropical Storm Noru brought periods of heavy rain and gusty winds to Iwo To when the core of tropical storm moved east of the island.  Tropical Storm Noru is forecast to turn toward the west on Sunday.  The outer bands on the northern side of Noru will continue to cause gusty winds and periods of heavier rain on Iwo To as the tropical storm passes south of the island.

Typhoon Lionrock Nearing Landfall in Japan

An upper level low is pulling Typhoon Lionrock toward a landfall in northern Japan.  At 8:00 p.m. EDT on Monday the center of Typhoon Lionrock was located at latitude 36.1°N and longitude 142.5°E which put it about 150 miles (240 km) south-southeast of Sendai, Japan.  Lionrock was moving toward the north-northwest 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 965 mb.

An upper level low west of Japan was pulling Typhoon Lionrock back toward the west-northwest.  At its current track and speed Typhoon Lionrock would make landfall on the northeastern coast of Honshu near Sendai in about six hours.

The structure of Typhoon Lionrock is changing as a result of cooler Sea Surface Temperatures and more vertical wind shear.  Lionrock is making a transition of a tropical cyclone to an extratropical cyclone.  The circulation is becoming more elongated and the typhoon is pulling cooler drier air into the western half of the circulation.  The wind field will tend to expand as the typhoon becomes extratropical.

Typhoon Lionrock will be capable of producing minor wind damage along its path.  It could also cause locally heavy rainfall and flash floods over northern Honshu.  It will pass over some of the same areas recently affected by Typhoon Mindulle.

Large Typhoon Lionrock Moves Closer to Japan

Large Typhoon Lionrock moved closer to Japan on Sunday.  At 11:00 p.m. EDT on Sunday the center of Typhoon Lionrock was located at latitude 31.1°N and longitude 142.1°W which put it about 385 miles (620 km) south-southeast of Tokyo, Japan.  Lionrock was moving toward the northeast at 19 m.p.h. (31 km/h).  The maximum sustained wind speed was 110 m.p.h. (180 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 952 mb.

Typhoon Lionrock retains a large symmetrical circulation.  Winds to typhoon force extend out about 40 miles (65 km) from the center.  Microwave satellite images suggest that there could be two eyewalls.  The inner eyewall is weaker on the western side and the larger outer eyewall has fewer thunderstorms on the northwestern side.  Other spiral bands are rotating around outside the outer eyewall.  Thunderstorms near the core of the circulation are generating upper level divergence which is pumping out mass primarily to the east of the typhoon.

The environment around Typhoon Lionrock would be marginally favorable for intensification.  Lionrock is moving over water where the Sea Surface Temperature (SSTs) is near 28°C.  An upper level trough west of Lionrock is generating southwesterly winds which are affecting the upper level divergence on the western side of the typhoon.  However, the vertical wind shear is not too significant.  On the other hand, concentric eyewalls often produce weakening as the inner eye wall dissipates and the stronger winds occur in the outer eyewall.  So, Lionrock could maintain a steady intensity or weaken slowly during the next 24 hours.  After that time is will move over cooler SSTs and it could weaken more.

The upper level trough is steering Typhoon Lionrock toward the northeast and that general motion is expect to continue for another 24 hours.  After that time, the upper trough will turn Lionrock back toward the northwest.  On its anticipated track Typhoon Lionrock will make landfall on northeast Honshu north of Tokyo in about 36 hours.  It could cause some wind damage.  Heavy rainfall and flash floods will also pose serious risks since Lionrock will move over some of the same areas affected by Typhoon Mindulle.

Typhoon Lionrock Turns in the Direction of Japan

After meandering southeast of Okinawa for several days Typhoon Lionrock started moving northeast toward Japan on Friday.  At 5:00 p.m. EDT on Friday the center of Typhoon Lionrock was located at latitude 23.7°N and longitude 133.0°E which put it about 920 miles (1485 km) south-southwest of Tokyo, Japan.  Lionrockk was moving toward the northeast at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 953 mb.

Typhoon Lionrock is very well organized.  It has a circular eye surrounded by a ring of strong thunderstorms.  Additional well formed spiral bands are rotating around outside the core of Lionrock.  Thunderstorms in the eyewall and spiral bands are generating upper level divergence which are pumping out mass in all directions.  The upper level divergence is inhibited a little on the far northern edge of the circulation by northerly winds impinging on Typhoon Lionrock.  Even so, there is enough upper level divergence to compensate for the strong inflow of mass near the surface and Typhoon Lionrock has been in a nearly steady state during recent hours.

Typhoon Lionrock is moving through an environment that should allow for it to maintain its intensity during the next severall days.  It is moving over water where the Sea Surface Temperature (SST) is near 30°C.  An upper level high over China is generating northerly winds which are effecting the extreme northern edge of the outflow from Lionrock.  However, the vertical wind shear is not very strong and it should have a minimal effect on the intensity of the typhoon in the short term.  Eventually, Typhoon Lionrock will move over cooler SSTs and into a region where the upper level winds are stronger and it will start to weaken before it reaches Japan.

Typhoon Lionrock is moving around the western end of a subtropical ridge and that ridge is beginning to steer it toward the northeast.  That general motion is expected to continue for the next several days.  Eventually Lionrock is forecast to turn more toward the northwest.  On its anticipated track Typhoon Lionrock could approach the eastern coast of Honshu in three or four days.  Lionrock could still be a typhoon at that time.

If Lionrock makes landfall in Honshu as a typhoon it will be strong enough to cause some wind damage.  In addition, Typhoon Lionrock could move over some of the same areas affected by Typhoon Mindulle.  Heavy rain caused by Lionrock could create the potential for additional flash flooding and mudslides.

Lionrock Becomes a Typhoon East of Okinawa

Tropical Storm Lionrock intensified into a typhoon east of Okinawa on Tuesday.  At 8:00 p.m. EDT on Tuesday the center of Typhoon Lionrock was located at latitude 25.3°N and longitude 132.8°E which put it about 340 miles (550 km) east-southeast of Okinawa.  Lionrock was moving toward the south-southwest at 11 m.p.h. (17 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 965 mb.

Lionrock is a fairly small typhoon.  Winds to tropical storm force only extend out about 150 miles (240 km) from the center.  The circulation of Typhoon Lionrock is very well organized.  A small distinct eye is visible on satellite imagery.  The eye is surrounded by a ring of strong thunderstorms.  Additional spiral rainbands are rotating around the core of Lionrock.  The thunderstorms around the eye are generating upper level divergence which is pumping out mass in all directions.

Typhoon Lionrock is in an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 30.5°C.  The upper level winds are weak and there is little vertical wind shear.  A small typhoon like Lionrock can intensify very quickly and it appears to be doing so.

An upper level ridge over China is steering Typhoon Lionrock slowly toward the south-southwest and that general motion is expected to continue for another day or two.  Lionrock could move into an area where the steering winds are weak and it could stall for a period of time.  Eventually, an upper level trough is expected to approach the area from the west and begin to pull Lionrock toward the north.

Tropical Storms Lionrock and Kompasu Spin Up Near Japan

A large cyclonic atmospheric gyre near Japan spun up two more tropical storms at the end of the week.  The Japan Meteorological Agency named two smaller circulations within the larger gyre Tropical Storm Lionrock and Tropical Storm Kompasu.

At 2:00 p.m. EDT on Saturday the center of Tropical Storm Kompasu was located at latitude 37.8°N and longitude 142.3°E which put it about 75 miles (120 km) east of Sendai, Japan.  Kompasu was moving toward the northwest at 26 m.p.h. (42 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.

At 2:00 p.m. EDT on Saturday the center of Tropical Storm Lionrock was located at latitude 30.6°N and longitude 135.7°E which put it about 530 miles (860 km) east-northeast of Okinawa.  Lionrock was moving toward the west-southwest 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 994 mb.

Tropical Storm Kompasu is located farther north and it is beginning to make a transition into an extratropical cyclone.  Kompasu is moving over water where the Sea Surface Temperature (SST) is near 26°C, but it is moving rapidly toward cooler SSTs.  Most of the thunderstorms are in a single primary rainband that wraps around the southern part of the circulation.  An upper level trough west of Japan is pulling southwesterly winds across the top of Tropical Storm Kompasu and the vertical wind shear is increasing.

The upper level trough is expected to turn Tropical Storm Kompasu toward the northeast.  On its anticipated track Tropical Storm Kompasu will move across Hokkaido in about 18 hours.  It will bring locally heavy rain and some wind.

Tropical Storm Lionrock is more well organized.  Several spiral bands of thunderstorms are wrapping around the southern and east sides of the center of circulation.  There is drier air in the western portion of the circulation and there are few thunderstorms in that part of Lionrock.  The thunderstorms east of the center are generating upper level divergence that is pumping mass toward the northeast away from core of Tropical Storm Lionrock.

Tropical Storm Lionrock is in an environment that is somewhat favorable for additional intensification.  It is moving over water where the SST is near 30°C.  The upper level trough west of Japan is generating some vertical wind shear.  The drier air in the western part of the circulation will also inhibit intensification, but Lionrock could gradually get better organized.  Upper level outflow from stronger Tropical Storm Mindulle, which is southwest of Lionrock, could produce enough vertical wind shear to weaken Lionrock at times.

The large atmospheric gyre is steering Tropical Storm Lionrock toward the west-southwest.  Lionrock could be pulled more toward the south as the larger, stronger Tropical Storm Mindulle passes east of it.  Tropical Storm Lionrock is expected to remain south of Japan during the next several days.  An alternative scenario would be for Tropical Storm Mindulle to intensify into a typhoon and grow large enough to absorb the circulation of Lionrock.