Tropical Cyclone Vicky Forms Near Samoa

Tropical Cyclone Vicky formed near Samoa on Thursday.  At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Vicky was located at latitude 15.2°S and longitude 170.6°W which put it about 35 miles (55 km) south of Pago Pago, American Samoa.  Vicky was moving toward the southeast at 9 m.p.h. (15 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.

A small low pressure system developed quickly within a large elongated trough extending east-southeast across Samoa on Thursday.  A small well defined circulation was evident on satellite imagery.  Thunderstorms developed near the center of the low pressure system and it was designated as Tropical Cyclone Vicky.  Storms near the center began to generate upper level divergence which pumped mass away from the tropical cyclone.  Winds to tropical storm force extended out 80 miles (130 km) from the center of circulation.  A weather station at Pago Pago reported a sustained wind speed of 43 m.p.h. (69 km/h) and a wind gust of 75 m.p.h. (120 km/h) when the developing tropical cyclone passed nearby.

Tropical Cyclone Vicky will move through an environment only marginally favorable for intensification during the next several days.  Vicky will move over water where the Sea Surface Temperature is near 28°C.  It will move under the western side of an upper level ridge over the South Pacific Ocean that extends southeast of Samoa.  The ridge will produce strong northwest winds which will cause moderate to strong vertical wind shear.  The wind shear will inhibit intensification and could cause Tropical Cyclone Vicky to weaken.  Since the circulation around Vicky is small, it could weaken rapidly if the wind shear increases.

Tropical Cyclone Vicky will move around the western side of a high pressure system over the South Pacific Ocean southeast of Samoa.  The ridge will steer Vicky toward the south during the next 24 to 48 hours.  On its anticipated track Tropical Cyclone Vicky could approach Niue in about 48 hours.  Vicky could be the equivalent of a tropical storm when it approaches Niue.