Tag Archives: SH11

Tropical Cyclone Winston Turning East

Tropical Cyclone Winston turned eastward on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Winston was located at latitude 25.2°S and longitude 175.3°E which put it about 545 miles (880 km) south-southwest of Suva, Fiji.  Winston was moving toward the east-southeast at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 105 m.p.h. (170 km/h).  The minimum surface pressure was 967 mb.

A subtropical ridge located north of Winston generated easterly winds over the top of the tropical cyclone.  The vertical wind shear caused Tropical Cyclone to weaken on Saturday.  Thunderstorms around the western side of the eyewall weakened and the eye became obscured at times as clouds blew over the top of it.  The vertical structure of the circulation is tilted toward the east with height because of the wind shear.  Tropical Cyclone Winston is likely to continue to weaken on Sunday.  However, it is moving over water where Sea Surface Temperature is near 29°C.  If the circulation maintains its integrity for another 48 hours, the wind shear could diminish and Winston could start to intensify again.

The subtropical ridge is steering Tropical Cyclone Winston toward the east.  The ridge is forecast to move toward the north and that will allow Winston to move more toward the northeast.  On its anticipated track Tropical Cyclone Winston could be near the southeastern islands of Fiji in about three days.

Tropical Cyclones Winston and Tatiana Form over SW Pacific

A pair of tropical cyclones named Winston and Tatiana formed over the southwestern Pacific Ocean on Thursday.  At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Winston was located at latitude 18.4°S and longitude 171.6°E which put it about 445 miles (720 km) west of Suva, Fiji.  Winston was moving toward the south at 7 m.p.h. (11 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 was 974 mb.

At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Tatiana was located at latitude 17.3°S and longitude 159.0°E which put it about 620 miles (1000 km) northwest of Noumea, New Caledonia.  Tatiana was moving toward the east-southeast at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 982 mb.

Tropical Cyclone Winston is the stronger and more well organized storm.  It has a well developed eye surrounded by a ring of strong thunderstorms.  Winston is in a very favorable environment.  It is moving over water where the Sea Surface Temperatures are near 31°C.  There is an upper level ridge over Winston and so the upper level winds are light and divergence is occurring in all directions.  Winston is likely to continue to intensify rapidly on Friday and it could become the equivalent of a major hurricane.

Tropical Cyclone Tatiana is smaller and not as well organized.  Tatiana is moving over water where the Sea Surface Temperatures are near 30°C.  However the western end of the same upper level ridge that is over Winston is generating brisk northerly winds over the top of Tropical Cyclone Tatiana.  As a result, vertical wind shear is inhibiting upper level divergence to the north of the center of Tatiana and it is also tilting the circulation toward the south with height.  Wind shear is likely to prevent Tatiana from intensifying significantly.

A subtropical ridge is steering both Winston and Tatiana toward the south.  Tropical Cyclone Winston will pass west of Fiji, but it could come close enough to the extreme southeastern islands of Vanuatu to bring wind and rain to some of those islands.  Tropical Cyclone Tatiana is likely to pass west of New Caledonia, but it could bring rain and higher surf to the west coast of that island.