February 25, 2011 - Tropical Cyclone Atu (17P) in the South Pacific Ocean

Tropical Cyclone Atu (17P) in the South Pacific Ocean

Severe Tropical Cyclone Atu raged over the southern Pacific Ocean in late February 2011, stretching from New Caledonia to Fiji. The U.S. Navy’s Joint Typhoon Warning Center (JTWC) reported that, as of 8:00 p.m. local time on February 21, Atu was located roughly 115 nautical miles (215 kilometers) east-southeast of Port Vila, Vanuatu. At that time, the storm had maximum sustained winds of 100 knots (185 kilometers per hour) and gusts up to 125 knots (230 kilometers per hour), making it a Category 3 Typhoon on the Saffir-Simpson Hurricane Wind Scale.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this natural-color image around 11:30 a.m. local time on February 21, 2011. The center of the storm appears just east of the Vanuatu archipelago.

On February 20, Severe Tropical Cyclone Atu reached peak strength as a Category 4 storm, battering the Shefa province with its extensive rain bands before beginning to weaken. By the evening of February 23, the outer bands of the now Category 2 storm spread above the upper North Island of New Zealand as the eye skirted the island offshore. At that time the storm had maximum sustained winds of 70 knots (130 kilometers per hour) and gusts up to 85 knots (155 kilometers per hour). In images acquired on that day, the cyclone appeared to be as wide as New Zealand is long.

After skirting Vanuatu and New Zealand, the eye of Cyclone Atu remained in the waters South Pacific Ocean, where the forces of vertical wind shear and cold water temperatures allowed it to weaken. By February 24 the storm had reduced in strength to a Tropical Storm and was in the process of becoming extra-tropical, which means it was losing the warm core temperature and was developing into a low-pressure system. The storm will continue to bring rain and wind to East Cape, New Zealand, as it dissipates.

Image Facts
Satellite: Terra
Date Acquired: 2/21/2011
Resolutions: 1km ( B), 500m ( B), 250m ( B)
Bands Used: 1,4,3
Image Credit: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC