Severe Tropical Cyclone Wilma was a powerful tropical cyclone that affected the Samoan Islands, Tonga and New Zealand. Forming out of a trough of low pressure on 19 January 2011 to the northwest of Fiji, Cyclone Wilma initially tracked eastward towards the Samoan Islands. On 22 January, the system took a sharp southward turn, bringing its centre directly over American Samoa the following day. After turning towards the southwest and accelerating, Wilma steadily intensified into a severe tropical cyclone before striking Tonga. The storm reached its peak intensity on 26 January as a Category 4 cyclone with winds of 185 km/h (115 mph) and a barometric pressure of 930 mbar (hPa; 27.46 inHg). Gradually re-curving towards the southeast, Wilma weakened quickly as it moved over cooler sea surface temperatures; by 28 January, it was downgraded to a tropical cyclone. Later that day, the storm brushed the North Island of New Zealand before transitioning into an extratropical cyclone.
Throughout Wilma's path, three countries were affected, with New Zealand experiencing the most severe damage. At least three fatalities in American Samoa have been blamed on the storm, two from flooding and one from high seas. In Tonga, "major damage" was reported across the Ha'apai Islands. In New Zealand, several homes were destroyed by the storm and hundreds of people were evacuated. However, there were no reports of fatalities. Torrential rain in the country, exceeding in some places, triggered 50-year flood events and isolated towns.
Meteorological history
Early on 19 January, RSMC Nadi reported that Tropical Disturbance 06F had developed along a trough of low pressure about to the northeast of Nadi, Fiji. During that day convection surrounding the disturbance gradually became more organised, and early the next day, RSMC Nadi reported that it had intensified into a tropical depression. On 22 January, The Joint Typhoon Warning Center (JTWC) started monitoring the system as Tropical Cyclone '08P'. Later the same day, RSMC Nadi upgraded Tropical Depression 06F to a tropical cyclone and named it 'Wilma'. Early on 24 January, RSMC Nadi further upgraded Wilma to a Category 2 Tropical Cyclone, and then Category 3 later that day. Wilma continued to strengthen and on 26 January, the RSMC Nadi upgraded it into a Category 4 Severe Tropical Cyclone. Early on 27 January, Wilma entered TCWC Wellington's area of responsibility. A few hours later, TCWC Wellington took full responsibility of Wilma, and downgraded it into a Category 3 Severe Tropical Cyclone. The next day, Wilma continued to weaken and TCWC Wellington further downgraded it into a tropical cyclone. Later that day, the JTWC, issuing their final warning, reported that the system took a southeast curve along the coast of North Island, New Zealand and started becoming extratropical. A few hours later, the TCWC Wellington discontinued advisories, no longer considering it a tropical cyclone.
Preparations, Impact and aftermath
American Samoa
Following harsh criticism for the lack of a warning siren after the 2009 Samoa earthquake and tsunami, in which more than 100 perished, the American Samoan Government ensured that residents were aware of Cyclone Wilma several days prior to its arrival. Many people boarded up their homes and Homeland Security was on standby in case of evacuations. As a precautionary measure, ten shelters were also opened on the island.
On 23 January, Wilma passed directly over American Samoa, bringing winds in excess of 95 km/h (60 mph). The local National Weather Service office recorded sustained winds of with gusts to while the National Oceanic and Atmospheric Administration's Earth System Research Laboratory on Cape Matatula, Tutuila, observed sustained winds of and gusts of . These winds downed numerous trees and power lines, leaving several towns and cities without electricity. Several structures also had their roofs blown off. Heavy rains amounting to triggered a few landslides but overall damage was light. With that, the Pago Pago International Airport was closed and the American Samoa Governor, Togiola Tulafono ordered local government agencies to help those in need. Wilma caused severe damage to the StarKist Samoa tuna cannery which was then shut down for a week. Across the region, three fatalities due to drowning were blamed on the storm. One of these was a child who was swept away by a swollen river while he was playing near it.