Tropical Cyclone Nat formed over the South Pacific Ocean west of Tahiti on Monday. At 1:00 p.m. EST on Monday the center of Tropical Cyclone Nat was located at latitude 15.3°S and longitude 163.6°W which put it about 965 miles (1560 km) west of Pappete, Tahiti. Nat was moving toward the east-southeast at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 996 mb.
A low pressure system over the South Pacific Ocean between Samoa and Tahiti strengthened on Monday and the Fiji Meteorological Service designated the system as Tropical Cyclone Nat. More thunderstorms formed near the center of Tropical Cyclone Nat. Storms near the center of Nat’s circulation generated upper level divergence that pumped mass away to the east of the tropical cyclone. Thunderstorms were also occurring in bands in the northern and eastern parts of Tropical Cyclone Nat. Bands in the western and southern part of Nat’s circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extend out 160 miles (260 km) in the northwest, northeast and southeast quadrants of Tropical Cyclone Nat. Winds to tropical storm force only extended out 25 miles (40 km) in the southwest quadrant of Nat.
Tropical Cyclone Nat will move through an environment somewhat favorable for intensification during the next 24 hours. Nat will move over water where the Sea Surface Temperatures are near 30°C. It will move under the eastern side of an upper level trough over the South Pacific Ocean northeast of New Zealand. The upper level trough will produce northwesterly winds that will blow toward the top of Nat’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will inhibit intensification, but the shear may not be strong enough to prevent intensification. Tropical Cyclone Nat could intensify gradually during the next 24 hours.
The upper level trough northeast of New Zealand will steer Tropical Cyclone Nat toward the east-southeast during the next 24 hours. On its anticipated track, Nat will move closer to Tahiti. The center of Tropical Cyclone Nat is forecast to pass north of Palmerston, Aitutaki and Mauke. The winds blowing around the southern side of Nat’s could bring gusty winds and rough seas to those places during the next 24 hours.