Tag Archives: Western North Pacific

Tropical Storm Son-tinh Develops East of Hainan Island

Tropical Storm Son-tinh developed east of Hainan Island on Monday night.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Son-tinh was located at latitude 19.4°N and longitude 116.9°E which put it about 430 miles east of Hainan Island.  Son-tinh was moving toward the west at 24 m.p.h. (35 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.

A small circulation began west of Guam last week and then it moved north of the Philippines on Monday.  Thunderstorms would form near the circulation and then wind shear would blow the tops of the storms away.  A small area of thunderstorms eventually persisted near the center of circulation on Monday and the Japan Meteorological Agency designated the system as Tropical Storm Son-tinh.  There was a small tight center of circulation in Son-tinh, but strong upper level winds were causing the distribution of thunderstorms to be asymmetrical.  More of the thunderstorms were occurring west of the center.  The circulation of Son-tinh was relatively small.  Winds to tropical storm force only extended out 80 miles (130 km) from the center of circulation.

Tropical Storm Son-tinh will move through an environment marginally favorable for intensification.  Son-tinh will move over water where the Sea Surface Temperature is near 30°C.  Tropical Storm Son-tinh is moving south of an upper level ridge.  The ridge is producing strong easterly winds which are blowing toward the top of the circulation.  Those winds will cause strong vertical wind shear and the shear will limit intensification.  Tropical Storm Son-tinh could intensify a little before it reaches Hainan Island, but it will weaken when it moves over the island.

The ridge north of Son-tinh is steering the tropical storm rapidly toward the west and that general motion is forecast to continue on Tuesday.  On its anticipated track Tropical Storm Son-tinh will reach Hainan Island in about 18 hours.  Son-tinh will bring gusty winds and locally heavy rain.  Isolated flash floods could occur,but the overall impacts are likely to be minor.

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 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.

Strengthening Tropical Storm Maria Brings Wind and Rain to Guam

Tropical Storm Maria strengthened quickly on Wednesday and it brought gusty winds and heavy rain to Guam.  The weather station at Andersen Air Force Base on Guam reported sustained winds to 44 m.p.h. (71 km/h) and wind gusts to 72 m.p.h. (116 km/h).  At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Maria was located at latitude 13.9°N and longitude 144.7°E which put it about 5 miles (10 km/h) south of Andersen Air Force Base.  Maria was moving toward the north-northwest at 11 m.p.h. (17 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 987 mb.  Tropical Storm Warnings remained in effect for Guam and Rota.  Tropical Storm Watches were in effect for Saipan and Tinian.

The circulation of Tropical Storm Maria organized quickly on Wednesday.  A tight center of circulation contracted at the center of Maria.  A partial ring of thunderstorms formed on the east side of the center.  Numerous bands of showers and thunderstorms were revolving around the core of the circulation.  Storms around the core generated well developed upper level divergence which pumped mass away in all directions from the tropical storm.  Winds to tropical storm force extended out about 95 miles (155 km) from the center of circulation.

Tropical Storm Maria will move through an environment very favorable for intensification.  Maria will move over water where the Sea Surface Temperature is near 30°C.  Tropical Storm Maria will move under the western portion of an upper level ridge where the upper level winds are weak.  There will little vertical wind shear.  Upper level lows east and west of the ridge will enhance the upper level divergence.  Tropical Storm Maria will strengthen into a typhoon on Thursday.  Maria could intensify rapidly and it is likely to become the equivalent of a major hurricane.

Tropical Storm Maria was moving around the western end of a subtropical ridge which was steering Maria toward the north-northwest.  The ridge is forecast to steer Maria toward the northwest during the next few days.  On its anticipated track Tropical Storm Maria will move away from the Marianas and toward the Ryukyu Islands.  Tropical Storm Maria will continue to cause gusty winds and drop locally heavy rain on the southern Marianas for a few more hours.  Conditions will improve on Thursday when Maria moves away the Marianas.

Tropical Storm Maria Prompts Warning for Guam

Tropical Depression 10W strengthened into Tropical Storm Maria on Wednesday and a Tropical Storm Warning was issued for Guam.  At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Maria was located at latitude 12.7°N and longitude 145.9°E which put it about 95 miles (155 km) southeast of Guam.  Maria was moving toward the north-northwest 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 1000 mb.  Tropical Storm Warnings were in effect for Guam and Rota.  Tropical Storm Watches were in effect for Saipan and Tinian.

The center of circulation in former Tropical Depression 10W became more well organized on Wednesday and the Japan Meteorological Agency designated the system as Tropical Storm Maria.  The circulation was still increasing in organization.  There was a distinct low level center of circulation.  Numerous bands of showers and thunderstorms were revolving around the center of circulation.  Storms near the center were generating upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Maria will move through an environment very favorable for intensification during the next few days.  Maria will move over water where the Sea Surface Temperature is near 30°C.  Tropical Storm Maria will move under the western end of an upper level ridge that is between two upper level lows which are east and west of the ridge.  The upper level winds will be relatively weak and there will be little vertical wind shear.  The combination of the ridge and two upper level lows will increase the upper level divergence.  Tropical Storm Maria will continue to strengthen.  Maria will become a typhoon later this week.  It could intensify rapidly once an eye forms and the inner core is well developed.

Tropical Storm Maria is moving around the western end of a subtropical ridge which is steering Maria toward the north-northwest.  On its anticipated track the center of Tropical Storm Maria will move near Guam and Rota later today.  A general motion toward the northwest is forecast for the next several days.  Maria could move in the direction of the Ryukyu Islands at the end of the week.

Tropical Storm Maria will bring gusty winds and heavy rain to the southern Mariana Islands.  The strongest winds and heaviest rain will affect Guam and Rota.  Gusty winds and heavy rain will also affect Saipan and Tinian.  Heavy rain could produce flash floods.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Prapiroon was moving over the Sea of Japan.  Prapiroon was bringing wind and rain to the northern Islands of Japan including Hokkaido and Honshu.  At 5:00 a.m. EDT on Wednesday the center of Tropical Storm Prapiroon was located at latitude 39.6°N and longitude 135.6°E which put it about 360 miles (585 km) west-southwest of Misawa, Japan.  Prapiroon was moving toward the northeast at 25 m.p.h. (40 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were winds gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 987 mb.

Tropical Storm Prapiroon Moves Toward Okinawa

Tropical Storm Prapiroon moved closer to Okinawa on Saturday.  At 11:00 a.m. EDT on Saturday the center of Tropical Storm Prapiroon was located at latitude 22.4°N and longitude 128.3°E which put it about 315 miles (510 km) south of Okinawa.  Prapiroon was moving toward the northwest at 8 m.p.h. (13 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 992 mb.

There was a distinct center of circulation in the middle of Tropical Storm Prapiroon, but the distribution of thunderstorms was asymmetrical.  The stronger thunderstorms were occurring in bands south and east of the center of circulation.  The bands north and west of the center consisted primarily of showers and low clouds.  A large upper level ridge over Asia was producing northerly winds which were blowing toward the top of Tropical Storm Prapiroon.  Those winds were causing moderate vertical wind shear and they were probably the reason for the asymmetric distribution of thunderstorms.  Those winds were also blocking upper level divergence to the north and west of Prapiroon.

Tropical Storm Prapiroon will move through an area marginally favorable for intensification during the next 24 to 36 hours.  Prapiroon will move over water where the Sea Surface Temperature is near 29°C.  So, there will be enough energy in the upper ocean to support intensification.  The upper level ridge will continue to cause some vertical wind shear, but Tropical Storm Prapiroon could move into an area where the upper level winds are a little weaker on Sunday.  If the wind shear decreases, then Tropical Storm Prapiroon will intensify.  There is still a chance that Prapiroon could strengthen into a typhoon when it passes near Okinawa.

Tropical Storm Prapiroon is moving around the western end of a subtropical ridge over the Pacific Ocean which is steering the tropical storm toward the northwest.  Prapiroon is forecast to move more toward the north when it reaches the western end of the ridge in 12 to 24 hours.  On its anticipated track the center of Tropical Storm Prapiroon could approach Okinawa in 12 to 18 hours.  The center of Prapiroon will likely pass west of Okinawa which would bring the strongest winds and heaviest rain over Okinawa.

Tropical Storm Prapiroon Forms South-Southeast of Okinawa

A distinct center of circulation formed within an area of thunderstorms south-southeast of Okinawa on Thursday night and the Japan Meteorological Agency designated the system as Tropical Storm Prapiroon.  At 8:00 p.m. EDT on Thursday the center of Tropical Storm Prapiroon was located at latitude 20.0°N and longitude 130.2°E which put it about 500 miles (800 km) south-southeast of Okinawa.  Prapiroon was moving toward the west at 7 m.p.h. (11 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 998 mb.

The circulation of Tropical Storm Prapiroon was still organizing.  More thunderstorms were forming close to the center of circulation.  There were more thunderstorms west of the center than there were east of the center.  Several bands of showers and thunderstorms in the outer part of the circulation were revolving around the core of Tropical Storm Prapiroon.  The storms in the core were generating upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Prapiroon formed beneath an upper level ridge that developed between an upper level low northwest of the Philippines and a much larger upper low east of the Marianas.  The winds in the upper ridge will be weak and there will be little vertical wind shear.  Prapiroon will move over water where the Sea Surface Temperature is near 29°C.  Tropical Storm Prapiroon will move through an environment very favorable for intensification.  Prapiroon will strengthen and it could intensify rapidly once the inner core organizes.  Tropical Storm Prapiroon could strengthen into a typhoon in 24 to 48 hours.

Tropical Storm Prapiroon was moving around the southwestern part of a subtropical ridge which was steering the tropical storm toward the west.  Prapiroon will turn toward the north in 12 to 24 hours when it reaches the western end of the ridge.  On its anticipated track Tropical Storm Prapiroon could approach Okinawa in about 36 hours.  Prapiroon could be a typhoon when it nears Okinawa.