Category Archives: South Pacific

Tropical Cyclone Ola Intensifying Northwest of New Caledonia

Tropical Cyclone Ola intensified rapidly on Saturday as it moved over the Coral Sea northwest of New Caledonia.  At 8:00 p.m. EST on Saturday the center of Ola was located at latitude 19.9°S and longitude 162.9°E which put it about 260 miles northwest of Noumea, New Caledonia.  Ola was moving toward the south-southeast at 8 m.p.h.  The maximum sustained wind speed was 80 m.p.h. and there were gusts to 95 m.p.h.  The minimum surface pressure was 970 mb.

Ola is moving over warm Sea Surface Temperatures (SSTs) and the environmental winds are generating upper level divergence to the southeast of the circulation.  The divergence pumped out mass and surface pressure decreased rapidly.  As a result, Ola intensified into the equivalent of a hurricane on Saturday.  Ola will remain over warm SSTs, but it will move into an area of stronger upper level winds when it moves farther southward.  It could intensify more during the next 24 hours, but it is likely to begin to weaken in 36 to 48 hours because of increasing vertical wind shear.

Counterclockwise flow around the western end of a subtropical ridge is steering Ola in a general southward direction.  That motion is expected to continue for another 24 hours.  A ridge of high pressure is expected to build south of Ola in a day or so.  The ridge could block Ola from moving any farther toward the south and turn it toward the southwest.  On the expected track, Ola would stay west of New Caledonia.  It is expected to weaken before it reaches Australia.

 

Tropical Cyclone Niko Passing East of Tahiti

The center of Tropical Cyclone Niko is passing east of Tahiti.  At 11:00 p.m. EST on Wednesday the center of Tropical Cyclone Niko was located at latitude 17.8°N and longitude 147.9°E which put it about 120 miles east of Papeete, Tahiti.  Niko was moving toward the south-southeast at 13 m.p.h.  The maximum sustained wind speed was 60 m.p.h. and there were gusts to 75 m.p.h.  The minimum surface pressure was estimated to be 985 mb.

Niko is a small tropical cyclone and even though it is passing within 120 miles of Tahiti, it is having a minimal effect on the weather there.  A subtropical ridge is expected to continue to steer Niko south-southeasterly direction, which will carry it away from Tahiti, although it could come close to the island of Mehetia.  The north-northwesterly winds that are steering Niko are also creating some wind shear.  The wind shear is limiting the intensification of Niko, but it is still over warm Sea Surface Temperatures and some intensification is possible on Thursday.  By Friday Niko is likely to be far enough south that is will start to move over cooler Sea Surface Temperatures and encounter stronger upper level winds.  So, Niko is likely to start to weaken in about 36 to 48 hours.

 

Tropical Cyclone Niko Forms North of Tahiti

A small cluster of thunderstorms north of Tahiti organized rapidly on Tuesday and it has now been classified as Tropical Cyclone Niko.  At 7:00 p.m. EST on Tuesday the center of Tropical Cyclone Niko was centered at latitude 14.1°S and longitude 150.2°W which put it about 250 miles north-northwest of Papeete, Tahiti and about 220 miles northeast of Bora-Bora.  Niko was moving toward the south-southeast at 8 m.p.h.  The maximum sustained wind speed was 50 m.p.h. and there were gusts to 65 m.p.h.  The minimum surface pressure was estimated to be 989 mb.

The circulation around Niko is small and winds to tropical storm force only extend about 80 miles from the center.  The small circulation is in an area of lighter winds in the upper levels.  The modest wind shear allowed thunderstorms to develop rapidly around the center of circulation and Niko organized quickly during the past 12 hours.  Niko is currently over warm Sea Surface Temperatures and it is in an environment favorable for intensification.  Small tropical cyclones can intensify rapidly and Niko has the potential to do so during the next 24 hours.  It could reach typhoon intensity on Wednesday.

A combination of a near equatorial ridge and a subtropical ridge are steering Niko in a south-southeasterly direction and this general motion is expected to continue.  The projected path takes the center of Niko east of Tahiti.  However, it could move near some smaller islands including Mataiva, Makate, and Tikehau.  Given the small size of the circulation, the area of damage is likely to be limited, but any place getting hit directly by the center of circulation could see wind damage.