Tag Archives: Samoa

Tropical Cyclone Amos Speeds Past Samoa and Weakens

Tropical Cyclone Amos weakened as it sped past Samoa on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Cyclone Amos was located at latitude 14.0°S and longitude 169.1°W which put it about 15 miles (25 km) north of Luma, Samoa.  Amos was moving toward the southeast at 19 m.p.h. (31 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 970 mb.

A ridge of high pressure east of Amos produced strong northwesterly winds which steered the tropical cyclone rapidly to the east-southeast on Saturday.  Those steering winds carried the core of Amos just north of the larger islands of Samoa.  Since hurricane force winds only extended out about 20 miles (30 km) from the center of circulation, the stronger winds stayed mostly over the open water.  A weather station in Pago Pago, Samoa reported a wind gust of 54 m.p.h. (87 km/h).

Tropical Cyclone Amos is currently bringing wind and rain to the Manua Islands of eastern Samoa which include Olosega, Ofu and Ta’u.  The rapid forward motion of Amos means that conditions should improve within a few hours.

The strong northwesterly winds are causing significant vertical wind shear that is rapidly weakening Tropical Cyclone Amos.  Amos is still moving over water where the Sea Surface Temperature is near 30°C, but the vertical wind shear should continue to weaken the tropical cyclone as it moves farther east of Samoa.

Strong Tropical Cyclone Amos Heading Toward Samoa

Tropical Cyclone Amos strengthened as it passed over Iles Wallis and headed toward Samoa on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Cyclone Amos was located at latitude 12.5°S and longitude 175.4°E which put it about 70 miles (115 km) north-northeast of Iles Wallis and about 360 miles (580 km) west-northwest of Pago Pago, Samoa.  Amos was moving toward the east at 11 m.p.h. (18 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. (205 km/h).  The minimum surface pressure was 956 mb.

The core of the circulation of Tropical Cyclone Amos is small but it is well organized.  There is a ring of the thunderstorms around an eye, but clouds from the taller thunderstorms are obscuring the eye on conventional satellite imagery.  Multiple bands of thunderstorms are rotating around the core of the circulation.  The thunderstorms are generating well developed upper level divergence which is pumping out mass in all directions.

Tropical Cyclone Amos is an environment favorable for further intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  The winds in the upper levels are weak and there is not much vertical wind shear.  Amos is likely to intensify during the next 24 hours and it could be the equivalent of a major hurricane when it reaches the western part of Samoa.

A ridge of high pressure is expected to steer Tropical Cyclone Amos toward the east-southeast during the nest several days.  On its anticipated track Amos could be approaching the western islands of Samoa in a little over 24 hours.  It could be the equivalent of a major hurricane at that time.

The Hurricane Intensity Index (HII) for Amos is currently 17.8.  The Hurricane Size Index (HSI) is 9.0 and the Hurricane Wind Intensity Size Index (HWISI) is 26.8.  Those indices suggest that the core of Tropical Cyclone Amos will be capable of causing major damage if it moves directly over any of the islands of Samoa.  In addition, Amos will produce locally heavy rain capable of causing flash floods.  It could also generate high waves and surges along the coasts of some of the islands.

Tropical Cyclone Amos to Bring Wind and Rain to Wallis and Samoa

Tropical Cyclone Amos intensified to the equivalent of a hurricane/typhoon on Thursday as it moved eastward across the South Pacific.  At 11:00 p.m. EDT on Thursday the center of Tropical Cyclone Amos was located at latitude 12.4°S and longitude 177.1°W which put it about 80 miles (130 km) northwest of Iles Wallis.  Amos was moving toward the east-northeast at 11 m.p.h. (18 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 974 mb.

Tropical Cyclone Amos is a small, tightly organized storm.  A primary band of thunderstorms wraps almost entirely around the center of circulation and an eyelike feature is visible intermittently on satellite imagery.  Additional bands of showers and thunderstorms are spiraling around the core of the circulation.  The thunderstorms are generating upper level divergence which is pumping out mass in all directions and causing the surface pressure to decrease.

The environment around Tropical Cyclone Amos is very favorable for further intensification.  It is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are very weak and there is little vertical wind shear.  Amos will continue to intensify on Friday and it could intensify rapidly.

A subtropical ridge north of Amos is steering the tropical cyclone toward the east and that general motion is expected to continue for several more days.  On its anticipated track Amos will pass near Iles Wallis on Friday.  Although the core of strongest winds will pass north of Iles Wallis, It could still bring strong winds, heavy rain and large waves to those islands.  On its anticipated track Amos could be approaching western Samoa within 36 hours.  It could be a very strong tropical cyclone at that time.

Tropical Cyclone Amos Forms North of Fiji

A center of circulation developed within a large area of thunderstorms north of Fiji on Wednesday and the system was designated as Tropical Cyclone Amos.  At 5:00 p.m. EDT on Wednesday the center of Tropical Cyclone Amos was located at latitude 12.5°S and longitude 179.4°W which put it about 145 miles (235 km) northwest of Ile Futuna.  Amos was stationary.  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 989 mb.

The circulation near the core of Tropical Cyclone Amos is still organizing.  A narrow primary band of thunderstorms is wrapping tightly around the core and an eye may be forming at the center of circulation.  Several other thin bands of showers and thunderstorms are rotating around the outer portions of the circulation.  The thunderstorms are generating some upper level divergence, but it is not well developed yet.

The environment is favorable for continued intensification.  Amos is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are not very strong and there is little vertical wind shear.  As the core of the circulation becomes more well organized, it will convert energy from the ocean more efficiently and the wind speeds will increase.  Tropical Cyclone Amos could intensify into the equivalent of a hurricane/typhoon within 24 to 36 hours.

Tropical Cyclone Amos is currently in an area where the steering currents are weak.  An upper level ridge is forecast to develop north of Amos and begin to steer the tropical cyclone toward the east.  On its anticipated track Amos could pass near Iles Wallis in 24 to 36 hours.  It could be approaching Samoa in two or three days.

Strong Tropical Cyclone Winston Heads for Fiji

Strong Tropical Cyclone Winston passed over northern Tonga as it moved closer to Fiji on Thursday.  At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Winston was located at latitude 17.6°N and longitude 175.1°W which puts it about 460 miles (740 km) east of Suva, Fiji.  Winston was moving toward the west at 14 m.p.h. (23 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 941 mb.  Tropical Cyclone Winston is the equivalent of a Category 3 hurricane on the Saffir-Simpson Scale and it would be considered a major hurricane if it were over the Atlantic Ocean.

Winston is a small, compact tropical cyclone with a well organized inner core.  It has an eye with a diameter of 15-20 miles (24-32 km) which is surrounded by a ring of strong thunderstorms.  A couple of bands of convection spiral into the core, but Tropical Cyclone Winston possesses some of the characteristics of an annular hurricane.

Winston continues to move through a very favorable environment.  The Sea Surface Temperature is near 30°C and upper level winds are relatively light.  There is not much vertical wind shear.  Tropical Cyclone Winston could intensify further on Friday.

A subtropical ridge to the south of Winston is steering the tropical cyclone toward the west-southwest.  That general motion is expected to continue for another day or two.  On its anticipated track Tropical Cyclone Winston could be very near the Lau Group of islands in eastern Fiji within 24 hours.  Winston is expected to move across the Koro Sea and it could be near Suva within 48 hours.

Winston is a strong tropical cyclone and it could bring destructive winds and heavy rain to parts of eastern Fiji.  It could also bring a storm surge and large waves, which may create dangerous conditions in low lying coastal areas.

Tropical Cyclone Winston Gets Stronger and Turns Back Toward Tonga

Tropical Cyclone Winston intensified into the equivalent of a Major Hurricane on Wednesday before it made a slow turn back toward Tonga and Fiji.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Winston was located at latitude 17.1°N and longitude 171.2°W which put it about 160 miles (255 km) north-northwest of Niue and about 240 miles (390 km) east-northeast of Neiafu, Tonga.  Winston was moving toward the west at 3 m.p.h. (5 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.

A very favorable environment of Sea Surface Temperatures near 30°C and little vertical wind shear allowed Tropical Cyclone Winston to intensify quickly into the equivalent of a Major Hurricane on Wednesday.  Winston is a small, symmetrical tropical cyclone.  There is a small, well formed eye at its center.  The eye is surrounding by a ring of strong thunderstorms and there are several spiral bands rotating outside the eyewall.  Hurricane force winds extend out about 40 miles (65 km) from the center and tropical storm force winds extend out about 140 miles (225 km) from the center.

Tropical Cyclone Winston could remain in a favorable environment for another 12 to 24 hours.  It has the potential to intensify further during that time.  After that time vertical wind shear could start to increase.  Since the circulation of Winston is relatively small, fluctuations in intensity could occur more quickly.

A subtropical ridge south of Winston turned the tropical cyclone back toward the west on Wednesday.  The ridge is expected to steer Winston slowly westward on Thursday.  The subtropical ridge will steer it toward the west-southwest at a faster speed on Friday.  On its anticipated track Tropical Cyclone Winston could approach the northern islands of Tonga in about 36 hours.  It could be a very strong tropical cyclone at that time and Winston could bring strong winds and heavy rain to those islands.  Winston could be approaching Fiji in about three days.

Tropical Cyclone Winston Intensifies Rapidly East of Tonga

Tropical Cyclone Winston intensified rapidly on Tuesday as it moved east of Tonga.  At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Winston was located at latitude 17.5°N and longitude 171.5°W which put it about 165 miles (270 km) northwest of Niue.  Winston was moving toward the east at 7 m.p.h. (11 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. (205 km/h).  The minimum surface pressure was 956 mb.

The upper level winds that were blowing over the top of Tropical Cyclone Winston diminished on Tuesday.  The decrease in vertical wind shear allowed Winston to intensify rapidly and it is now the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.  Tropical Cyclone Winston remains in a favorable environment.  It is over water where the Sea Surface Temperature is near 30°C.  Winston has a well formed eye surrounded by an eyewall containing strong thunderstorms.  Multiple spiral bands are rotating around the core of the circulation.  Winston should continue to intensify and it could intensify rapidly on Wednesday.

A subtropical ridge to the northeast of Winston is slowing the eastward motion of the tropical cyclone.  Winston could continue to move a little farther east on Wednesday before the ridge blocks its motion.  The ridge is forecast to strengthen and extend to the west later this week.  As the ridge extends westward it will force Winston to start to move back toward the southwest.  On its anticipated track Tropical Cyclone Winston could move between Niue and Samoa on Wednesday.  Winston could approach Tonga from the northeast as a much stronger tropical cyclone on Friday.

Tropical Cyclone Winston Moving Through Tonga

Tropical Cyclone Winston brought wind and rain as it moved through Tonga on Monday.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Winston was located at latitude 18.9°S and longitude 175.0°W which put it about 405 miles (650 km) east-southeast of Suva, Fiji and about 140 miles (225 km) north of Nuku’ Alofa, Tonga.  Winston was moving toward the east-northeast at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 990 mb.

The structure of Tropical Cyclone Winston improved on Monday.  A primary rainband wrapped much of the way around the eye and a nearly complete eyewall reformed.  Additional bands of thunderstorms formed mainly in the eastern half of the circulation.  Thunderstorms increased the upper level divergence to the northeast of Winston.

The environment remains marginal for intensification.  A subtropical ridge is generating southwesterly winds over the top of Tropical Cyclone Winston.  Those winds are generating moderate vertical wind shear and are inhibiting re-intensification of Winston.  However, the tropical cyclone is moving over water where the Sea Surface Temperatures are near 30°C.  If the upper level winds diminish, then Tropical Cyclone Winston could re-intensify during the next several days.

The subtropical ridge is steering Winston toward the east-northeast and that general motion is expected to continue for another 24 to 48 hours.  On it anticipated track Tropical Cyclone Winston will move through the Vava’u Group of Tonga.  It could bring strong winds and locally heavy rain to those islands.  Winston could be between Samoa and Niue later this week.

Tropical Cyclone Victor Intensifies East of Niue

Tropical Cyclone Victor intensified on Monday and it is now the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.  At 4:00 p.m. EST on Monday the center of Tropical Cyclone  Victor was located at latitude 20.2°S and longitude 166.3°W which put it about 175 miles (280 km) east-southeast of Niue.  Victor was moving toward the south-southwest at 5 m.p.h. (8 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. (205 km/h).  The minimum surface pressure was 956 mb.

Tropical Cyclone Victor has an unusual structure.  It has a very large eye, which is about one degree of longitude across.  The eye is surrounded by a narrow eyewall of strong thunderstorms and a couple of thin, primary rainbands.  Winds to tropical storm force extend out about 200 miles (320 km) from the center of circulation.  The thunderstorms in the eyewall are generating strong upper level divergence which is pumping out mass.  The eye has appeared to contract a bit on recent satellite imagery, which could be a sign of further intensification.

Tropical Cyclone Victor is an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature (SST) is near 27°C.  An upper level ridge located northeast of Victor is producing some light northwesterly winds over the top of the tropical cyclone.  However, the vertical wind shear is minimal and it is not inhibiting intensification at this time.  Victor could continue to intensify on Tuesday.  Later this week Tropical Cyclone Victor will move into an environment with cooler SSTs and more wind shear.  Victor will start to weakening when it enters that environment.

The ridge northeast of Victor is getting stronger and it is forcing the tropical cyclone to move toward the west-southwest.  That general motion is expected to continue for the next several days.  On its anticipated track the core of Tropical Cyclone Victor with the strongest winds will pass south of Niue during the next 48 hours.  However, Tropical Cyclone Victor could bring a period of strong winds and rain to Niue as it moves south of the islands.  The large wind field around Victor could also generate significant waves and surges.  Tropical Cyclone Victor could be approaching Tonga later this week.

Tropical Cyclone Ula Bringing Strong Wind to SE Fiji

Tropical Cyclone Ula is bringing strong winds, heavy rain and high surf to the extreme southeastern islands of Fiji.  At 4:00 p.m. EST on Saturday the center of Tropical Cyclone Ula was located at latitude 19.4°S and longitude 178.0°W which put it about 265 miles ( 430 km) east-southeast of Suva, Fiji.  Ula was moving toward the southwest at 9 m.p.h. (15 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. (205 km/h).  The minimum surface pressure was 961 mb.  Tropical Cyclone Ula was the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.

The inner core structure of Tropical Cyclone Ula changed on Saturday and it may have gone through an eyewall replacement cycle.  Ula started the day with a small pinhole eye, but recent visible satellite imagery indicates that it has a larger, symmetrical eye.  Even though the inner core structure has changed, Tropical Cyclone Ula maintained its intensity.  The structure of Ula is still symmetrical, but most of the stronger thunderstorms are south and west of the center of circulation.

Tropical Cyclone Ula remains in an environment that is favorable for intensification.  It is over water where the Sea Surface Temperature (SST) is near 28°C.  The upper level winds are light and there is not much vertical wind shear.  The favorable environment could allow Ula to maintain its intensity for another 12 to 24 hours.  After that time the tropical cyclone will move into an area where the SSTs are cooler and the upper level winds are stronger.  Cooler water and more vertical wind shear will cause Tropical Cyclone Ula to weaken.

A subtropical ridge is steering Tropical Cyclone Ula toward the southwest.  Ula is nearing the western end of the ridge and it is likely to turn more toward the south in a day or two.  The center of Tropical Cyclone Ula is near Vatoa, Ogea Levu and Ogea Driki.  It is bringing strong winds, heavy rain and large waves to those islands.  It will move near Ono-i-lau, Tuvana-i-colo and Tuvana-i-ro during the next few hours and conditions will get worse on those islands.