Weakened Tropical Cyclone Sarai Moves Across Tonga

A weakened Tropical Cyclone Sarai moved across Tonga on Monday.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Sarai was located at latitude 20.6°S and longitude 174.9°W which put it about 30 miles (50 km) northeast of Nuku Alofa, Tonga.  Sarai was moving toward the northeast at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 989 mb.

Tropical Cyclone Sarai moved south of an upper level ridge on Monday.  The upper level ridge produced strong westerly winds which blew across the top of Sarai.  Those winds caused strong vertical wind shear and they blew the tops off of thunderstorms in Tropical Cyclone Sarai.  The circulation in the lower levels of Sarai remained intact, but it consisted of showers and lower clouds.  The wind speed gradually decreased during Monday.

The center of Tropical Cyclone Sarai passed just north of the Tongatapu Group of islands.  Sarai passed over the Ha’apai Group of islands.  Tropical Cyclone Sarai brought winds to tropical storm force and squally weather to parts of Tonga.  Rainfall amounts were relatively light because the wind sheared the tops off of any thunderstorms which started to form.

Tropical Cyclone Sarai will move through an environment unfavorable for intensification.  Sarai will move over water where the Sea Surface Temperature is near 27°C.  The upper level ridge will continue to cause strong vertical winds shear.  The wind shear will make it very difficult for new thunderstorms to form.  Tropical Cyclone Sarai is likely to weaken slowly as the circulation in the lower levels spins down.

Tropical Cyclone Sarai will move south of a subtropical high pressure system over the South Pacific Ocean.  The high will steer Sarai toward the east during the next several days.  On its anticipated track Tropical Cyclone Sarai will move south of the Vava’u Group of Islands during the next 24 hours.  Sarai could reach Niue in less than 30 hours.