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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 Maria Makes Landfall in China

The center of Typhoon Maria made landfall Lianjiang, China on Tuesday night.  At 11:00 p.m. EDT on Tuesday the center of Typhoon Maria was located at latitude 26.7°N and longitude 119.3°E which put it near Ningde, China.  Maria was moving toward the west-northwest at 22 m.p.h. (35 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 135 m.p.h. (215 km/h).  The minimum surface pressure was 952 mb.

Two concentric eyewalls formed at the center of Typhoon Maria before it made landfall on the coast of China.  The inner eyewall was dissipating, but it still existed at the time of landfall.  The outer eyewall started to contract prior to landfall.  Winds to typhoon force extended out about 65 miles (105 km) from the center of circulation in the part of the circulation over water.  Winds to tropical storm force extended out about 235 miles (380 km) from the center in the part of the circulation over water.

Typhoon Maria brought strong winds and a storm surge to the coast of Zhejiang province when it made landfall.  Maria was also dropping heavy rain and flash flooding could occur.  Typhoon Maria was moving around the western end of a subtropical ridge over the Western North Pacific Ocean.  The ridge was steering Maria toward the west-northwest, but the typhoon is likely to turn more toward the northwest when it moves farther inland.  Typhoon Maria will weaken as it moves inland over eastern China, but it will still drop heavy rain and flooding will be a significant risk.

Typhoon Maria Drops Heavy Rain on Taiwan

Typhoon Maria dropped heavy rain on Taiwan on Tuesday after it brought wind and rain to the southern Ryukyu Islands.  At 5:00 p.m. EDT the center of Typhoon Maria was located at latitude 26.5°N and longitude 121.4°E which put it about 85 miles (135 km) north-northeast of Taipei, Taiwan.  Maria was moving toward the west-northwest at 22 m.p.h. (35 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 949 mb.

A primary rainband wrapped around the existing eye and eyewall in Typhoon Maria and the structure exhibited concentric eyewalls.  The inner eyewall started to weaken as more air converged and rose in the much larger outer eyewall.  The wind speeds decreased slowly as the inner eyewall weakened.  The concentric eyewalls altered the structure of Typhoon Maria and the size of the circulation increased.  Winds to typhoon force extended out about 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extended out about 235 miles (380 km) from the center.

Typhoon Maria was moving around the southern side of a subtropical ridge over the Western North Pacific Ocean.  The ridge was steering Maria toward the west-northwest and a general motion in that direction is expected to continue for another 12 to 24 hours.  On its anticipated track the center of Typhoon Maria will pass north of Taiwan, but Maria will continue to drop heavy rain over Taiwan.  Maria will make landfall on the east coast of China near Fuding during the next 6 to 12 hours.  The typhoon will bring gusty winds, a storm surge and heavy rain to Zhejiang province in eastern China.  The heavy rain could cause flash floods.

Typhoon Maria Nears Southern Ryukyu Islands

Typhoon Maria neared the southern Ryukyu Islands on Monday night.  At 11:00 p.m. EDT on Monday night the center of Typhoon Maria was located at latitude 24.3°N and longitude 126.4°E which put it about 130 miles (210 km) east of Ishigaki, Japan.  Maria was moving toward the west-northwest at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 125 m.p.h. (205 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 949 mb.

Typhoon Maria weakened slowly on Monday, but it remained a powerful typhoon.  Maria moved over some slightly cooler water mixed to the surface by recent Typhoon Prapiroon when it passed near the Ryukyu Islands.  Maria was unable to extract enough energy from the upper ocean to maintain the intense wind speeds it produced during the weekend.  However, Typhoon Maria was still the equivalent of a major hurricane.  There was a circular eye with a diameter of 35 miles (55 km).  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Several bands of thunderstorms were revolving around the core of Typhoon Maria.   Storms in the core were generating strong upper level divergence which was pumping mass away from the center of circulation.

Winds to typhoon force extended out about 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extended out about 200 miles from the center.  The Hurricane Intensity Index (HII) for Typhoon Maria was 23.6.  The Hurricane Size Index (HSI) was 23.8 and the Hurricane Wind Intensity Size Index (HWISI) was 47.4.  Those indices indicated that Typhoon Maria was capable of causing widespread major damage.

Typhoon Maria will move through an environment capable of sustaining a strong typhoon on Tuesday.  Maria will move west of the cooler water mixed to the surface by previous Typhoon Prapiroon and it will move over water where the Sea Surface Temperature is near 29°C.  Typhoon Maria will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Maria could weaken slowly on Tuesday if it is unable to extract enough energy from the upper ocean to sustain its circulation.  It could strengthen a little when it moves over slightly warmer water if it has time to extract more energy from the ocean.

Typhoon Maria was moving south of a subtropical ridge over the Western North Pacific Ocean.  The ridge was steering Maria toward the west-northwest and that general motion is expected to continue during the 36 hours.  On its anticipated track Typhoon Maria will reach the southern Ryukyu Islands in six to twelve hours.  Maria will bring destructive winds, heavy rain and a storm surge.  It will be capable of causing major damage to Miyako Jima, Ishigaki Jima, Iriomote Jima and the other islands in the southern Ryukyus.  The strongest part of Typhoon Maria will pass south of Okinawa, which could experience rainbands in the outer portion of the circulation.  Typhoon Maria will pass near northern Taiwan in about 18 hours.  It will bring strong winds and locally heavy rain to that area and flash floods could occur.  Maria could be near Fuding on the coast of China in about 24 hours.

Dangerous Typhoon Maria Churns Toward the Ryukyu Islands

Dangerous Typhoon Maria churned closer to the Ryukyu Islands on Sunday.  At 11:00 p.m. EDT on Sunday the center of Typhoon Maria was located at latitude 22.1°N and longitude 132.7°E which put it about 485 miles (780 km) southeast of Okinawa.  Maria was moving toward the west-northwest at 19 m.p.h. (31 km/h).  The maximum sustained wind speed was 155 m.p.h. (250 km/h) and there were wind gusts to 190 m.p.h. (305 km/h).  The minimum surface pressure was 922 mb.

Typhoon Maria has a large symmetrical circulation.  There is a circular eye with a diameter of 32 miles (52 km) at the center of Maria.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring of storms.  Multiple bands of showers and thunderstorms are revolving around the core of Typhoon Maria.  Storms around the core are generating well developed upper level divergence which is pumping away large amounts of mass from the typhoon.

Winds to typhoon force extend out about 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extend out about 230 miles (370 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Maria is 33.3.  The Hurricane Size Index (HSI) is 23.7 and the Hurricane Wind Intensity Size Index (HWISI) is 57.0.

Typhoon Maria will remain in an environment favorable for strong typhoons for another 24 to 36 hours.  Maria will move over water where the Sea Surface Temperature is near 29°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Maria will remain a large and dangerous typhoon for another day or two.

Typhoon Maria was moving south of a subtropical ridge over the Western North Pacific Ocean.  The ridge was steering Maria toward the west-northwest and a general motion toward the west-northwest is likely to continue for another day or two.  On its anticipated track Typhoon Maria will approach the southern Ryukyu Islands in about 24 hours.  Maria could be near northern Taiwan in about 36 hours and it could approach the coast of China in about 48 hours.

Typhoon Maria will bring strong winds, locally heavy rain and a significant storm surge.  Maria will be capable of causing major damage over a widespread area.

Powerful Typhoon Maria Spins East of Taiwan

Powerful Typhoon Maria spun east of Taiwan on Saturday.  At 11:00 p.m. EDT on Saturday the center of Typhoon Maria was located at latitude 19.4°N and longitude 138.3°E which put it about 950 miles (1530 km) east-southeast of Okinawa.  Maria was moving toward the northwest at 13 m.p.h. (10 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 925 mb.

Typhoon Maria appeared to complete an eyewall replacement cycle on Saturday.  The completion of the cycle resulted in a  larger circulation.   There was an eye which had a diameter of 24 miles (38 km).  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of the circulation.  The rainbands northwest in the northwestern quadrant of Typhoon Maria were a little weaker than the bands in the other parts of the circulation.  Storms in the core of Maria were generating upper level divergence which was pumping mass away to the northeast of the typhoon.

Winds to typhoon force extended out about 70 miles (110 km/h) from the center of circulation.  Winds to tropical storm force extended out about 200 miles (320 km) from the center.  The Hurricane Intensity Index (HII) for Maria was 37.9.  The Hurricane Size Index (HSI) was 24.5 and the Hurricane Wind Intensity Size Index (HWISI) was 62.4.

Typhoon Maria will move through an environment mostly favorable for powerful typhoons on Sunday.   Maria will move over water where the Sea Surface Temperature is near 30°C.  It will move through an environment where the upper level winds are weak and there will be little vertical wind shear.  There appears to be some sinking motion and drier air northwest of Maria and that may be the reason why the rainbands were weaker in that part of the typhoon.  The drier air could inhibit further strengthening.  Typhoon Maria is likely to remain strong for another 24 to 48 hours.

Typhoon Maria was moving around the southern portion of a subtropical ridge over the Western North Pacific.  The ridge was steering Maria toward the northwest.  The ridge is forecast to strengthen and it will steer Typhoon Maria more toward the west-northwest.  On its anticipated track Typhoon Maria could approach the southern Ryukyu Islands in about 48 hours.  Maria could be near the northern end of Taiwan in about 60 hours.

Typhoon Maria Rapidly Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Maria rapidly intensified into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Typhoon Maria was located at latitude 16.2°N and longitude 141.9°E which put it about 250 miles (405 km) northwest of Guam.  Maria was moving toward the northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 918 mb.

Typhoon Maria continued to intensify rapidly on Thursday night and it reached the equivalent of Category 5 on the Saffir-Simpson Scale.  Maria is a strong, well organized typhoon.  There is a small circular eye at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds were occurring that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Maria.  Storms in the core were generating strong upper level divergence which was pumping large amounts of mass away from the typhoon.  The rapid removal of mass allowed the surface pressure to decrease quickly and the wind speeds to increase rapidly.

Winds to typhoon/hurricane force extended out about 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extended out about 155 miles (250 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Maria was 43.5.  The Hurricane Size Index (HSI) was 17.8 and the Hurricane Wind  Intensity Size Index (HWISI) was 51.3.

Typhoon Maria will move through an environment favorable for strong tropical cyclones for another day or two.  Maria will move over water where the Sea Surface Temperature is 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 Maria could intensify further on Friday.  However, a rainband could wrap around the existing eye and eyewall.  If that occurs, then an eyewall replacement cycle will begin.  Maria would weaken while the inner eyewall dissipates.  The typhoon could strengthen again if the outer eyewall contracts around the center of circulation.

Typhoon Maria was moving south of a subtropical ridge which was steering Maria toward the northwest.  The northwesterly motion is expected to continue for another 24 to 48 hours.  After that time the ridge is forecast to strengthen and steer Maria more toward the west-northwest.  on its anticipated track Typhoon Maria could approach Okinawa and the Ryukyu Islands in about four days.  Maris is likely to be a powerful typhoon at that time.

Typhoon Maria Rapidly Intensifies Into Equivalent of Major Hurricane

Typhoon Maria rapidly intensified Thursday into the equivalent of a major hurricane as it moved west of the Mariana Islands.  At 5:00 p.m. EDT on Thursday the center of Typhoon Maria was located at latitude 15.7°N and longitude 142.1°E which put it about 210 miles (340 km) northwest of Guam.  Maria was moving toward the northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 125 m.p.h. (205 km/h) and there were wind gusts to 155 m.p.h. (250 km/h).  The minimum surface pressure was 950 mb.

After striking Guam as a tropical storm on Wednesday Maria rapidly intensified into a strong typhoon on Thursday.  A circular eye was evident on satellite imagery.  The eye was surrounded by a ring of strong thunderstorms.  Several bands of showers and thunderstorms were revolving around the core of the circulation.  Storm in the core were generating strong upper level divergence which was pumping mass away from the typhoon in all directions.  Winds to typhoon force extended out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extended out about 155 miles (250 km) from the center.

The Hurricane Intensity Index (HII) for Typhoon Maria was 23.6.  The Hurricane Size Index (HSI) was 14.1 and the Hurricane Wind Intensity Size Index (HWISI) was 37.7.

Typhoon Maria will continue to move through an environment favorable for intensification for another day or two.  Maria will move over water where the Sea Surface Temperature is near 30°C.  It will move through a region of weaker winds between an upper level low to the west and an upper level low to the east.  There will be little vertical wind shear.  Typhoon Maria is likely to intensify more on Friday and it could become the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.  An eyewall replacement cycle could occur if one of the rainbands wraps around existing eye and eyewall.  If an eyewall replacement cycle starts, it will cause Typhoon Maria to weaken at least temporarily.

Typhoon Maria was moving south of a subtropical ridge over the Western North Pacific Ocean.  The ridge was steering Maria toward the northwest.  A general motion toward the northwest is expected to continue for another day or two.  The ridge is forecast to strengthen after that time and it will steer Typhoon Maria more toward the west-northwest.  On its anticipated track Maria will pass south of Iwo To.  Typhoon Maria could approach Okinawa and the Ryukyu Islands in four or five days.