Tropical Cyclone Zazu brought wind and rain to northern Tonga on Monday. At 10:00 a.m. EST on Monday the center of Tropical Cyclone Zazu was located at latitude 18.9°S and longitude 174.4°W which put it about 40 miles (65 km) west of Neiafu, Tonga. Zazu was moving toward the south-southwest at 6 m.p.h. (10 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 991 mb.

Tropical Cyclone Zazu brought wind and rain to the Vava’u Group of islands in northern Tonga on Monday. The circulation around Zazu was intensifying. The inner end of a rainband wrapped partly around the eastern side of the center of circulation. Storms near the center generated upper level divergence which pumped mass away from the tropical cyclone. Thunderstorms were occurring in bands in the eastern half of Tropical Cyclone Zazu. Bands in the western half of the circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 150 miles (240 km) on the eastern side of Zazu. Winds to tropical storm force extended out 75 miles (120 km) in the western half of the circulation.

Tropical Cyclone Zazu will move through an environment favorable for intensification during the next 24 hours. Zazu will move over water where the Sea Surface Temperature is near 29°C. It will move south of an upper level trough over the South Pacific Ocean. The trough will produce westerly winds which will blow toward the top of Zazu. Those winds will cause some vertical wind shear and they are contributing to the asymmetrical distribution of thunderstorms. The shear will inhibit intensification of Tropical Cyclone Zazu, but the shear will not be strong enough to prevent Zazu from intensifying. Tropical Cyclone Zazu could strengthen into the equivalent of a hurricane/typhoon during the next 24 hours. The vertical wind shear will increase in a day or so, and Zazu will start to weaken when that happens.

The upper level trough will start to steer Tropical Cyclone Zazu toward the southeast during the next 24 hours. On its anticipated track Zazu will move between Tonga and Niue. Tropical Cyclone Zazu will continue to cause gusty winds and heavy rain over parts of Tonga during the next 24 hours. Rainbands on the eastern side of Zazu could affect Niue on Tuesday.

Elsewhere over the South Pacific Ocean, Tropical Cyclone Yasa strengthened to the equivalent of a hurricane/typhoon west-northwest of Fiji. At 10:00 a.m. EST on Monday the center of Tropical Cyclone Yasa was located at latitude 15.5°S and longitude 171.6°E which put it about 400 miles (640 km) west-northwest of Nadi, Fiji. Yasa was moving toward the north-northwest at 3 m.p.h. (5 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 976 mb. Tropical Cyclone Yasa is forecast to move toward Fiji and to intensify into the equivalent of a major hurricane.