Tag Archives: Tonga

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.

Tropical Cyclone Ula Bringing Wind and Rain to Northern Tonga

Tropical Cyclone Ula is bringing wind and rain to islands in northern Tonga.  At 10:00 p.m. EST on Friday the center of Tropical Cyclone Ula was located at latitude 18.3°N and longitude 175.6°W which put it about 100 miles (160 km) north-northwest of Tongatapu, Tonga.  Ula was moving toward the west-southwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 115 m.p.h. (150 km/h) and there were wind gusts to 135 m.p.h. (215 km/h).  The minimum surface pressure was 959 mb.

Lupepau’u airport on Vava’u reported maximum sustained winds of 65 m.p.h. (105 km/h) and wind gusts to 100 m.p.h. (160 km/h) when the center Tropical Cyclone Ula passed north of it.  Ula also brought strong winds and heavy rain to Tafahi, Fonaulei and Toku in northern Tonga.

Tropical Cyclone Ula intensified quickly during the past few hours and a pinhole eye is visible on conventional satellite images.  The eye is surrounded by a tight ring of strong thunderstorms.  Several spiral bands are rotating around the center of Ula.  One of the primary rainbands may be wrapping around the pinhole eye and concentric eyewalls may be developing.  Thunderstorms in the core of Tropical Cyclone Ula are generating upper level divergence that is pumping out mass in all directions.

Tropical Cyclone Ula is in an environment favorable for intensification.  Ula is moving over water where the Sea Surface Temperature (SST) is near 28°C.  The upper level winds are relatively light and there is not much vertical wind shear.  Ula could intensify further during the next few hours, although an eyewall replacement cycle could cause fluctuations in intensity.  Tropical Cyclone Ula could move into an area where the upper level winds are stronger in 24 to 48 hours.  Ula will also move over cooler SSTs in several days.  The combination of more wind shear and cooler SSTs will weaken the tropical cyclone.

A subtropical ridge is steering Tropical Cyclone Ula toward the west-southwest and that general motion is expected to continue for another day or so.  After that time Ula will reach the western end of the ridge and turn more toward the south.  On its expected track Tropical Cyclone Ula could be approaching the southeastern islands of Fiji in about 24 hours.

Tropical Cyclone Ula Becomes Equivalent of Cat. 2 Hurricane South of Samoa

Tropical Cyclone Ula intensified quickly Wednesday into the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.  At 4:00 p.m. EST on Wednesday the center of Tropical Cyclone Ula was located at latitude 16.3°N and longitude 170.4°W which put it about 135 miles (220 km/h) south-southeast of Pago Pago, Samoa.  Ula was moving toward the 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 961 mb.

Tropical Cyclone Ula has a small, well organized inner core.  An eye has appeared intermittently on satellite imagery.  Thunderstorms near the core are generating upper level divergence which is pumping out mass and allowing the surface pressure to decrease.

Tropical Cyclone Ula is moving through an environment favorable for intensification.  It is over water where the Sea Surface Temperature is near 28.5°C.  The upper level winds are not very strong and there is not much vertical wind shear.  Ula could intensify a little more during the next 24 hours.

A subtropical ridge is steering Tropical Cyclone Ula toward the southwest and a general west-southwesterly motion is expected to continue during the next several days.  Ula is centered between Samoa, Niue and Tonga.  On its anticipated track Tropical Cyclone Ula will approach Tonga in about 24 hours.  It could be approaching Fiji in about three days.  Tropical Cyclone Ula is capable of bringing strong winds, high surf and heavy rain to the islands in its path.