Cyclone Evan

Severe Tropical Cyclone Evan was considered to be the worst tropical cyclone to affect the island nation of Samoa since Cyclone Val in 1991 and was the strongest storm to impact the main South Pacific islands until Winston in 2016. The system was first noted on December 9, 2012, as a weak tropical depression about 700 km to the northeast of Suva, Fiji. Over the next couple of days, the depression gradually developed further before it was named Evan on December 12, as it had fully developed into a tropical cyclone. During that day the system moved toward the Samoan Islands and gradually intensified, before the system slowed and severely affected the Samoan Islands during the next day with wind gusts of up to 130 mph.

The storm moved east and impacted the French islands of Wallis and Futuna before affecting Samoa and American Samoa. On December 16, Evan turned to the south and paralleled western areas of Fiji.

Meteorological history
The tropical depression that was to become Severe Tropical Cyclone Evan was first noted by the Fiji Meteorological Service (FMS) on December 9, while it was located within the South Pacific Convergence Zone near the Fijian dependency of Rotuma. At this stage, the system's broad low-level circulation was poorly organised, while the majority of atmospheric convection was fragmented and located over its northeastern quadrant. Over the next day, the system subsequently moved south-eastwards within an area favourable for further development, with low vertical windshear, sea surface temperatures of 29 - 30 C and favourable outflow. During December 11, the systems low-level circulation centre started to rapidly consolidate, as it passed around 55 km to the southwest of the French Territory of Futuna. Later that day as the depression became equivalent to a tropical storm and develop a small eye on microwave imagery, the United States Joint Typhoon Warning Center initiated advisories on the system and designated it as Tropical Cyclone 04P. This was followed by the FMS naming the system as Evan the following day, after it had become a Category 1 tropical cyclone on the Australian tropical cyclone intensity scale.

After the system was named, the upper-level ridge continued to steer Evan eastward, toward the Samoan islands, as the cyclone quickly intensified. By December 12, as the system started to impact the Samoan Islands with gale and storm force wind speeds, RSMC Nadi reported that the system had become a category 2 tropical cyclone with 10-minute sustained wind speeds of 90 km/h. The JTWC also reported that day that the system had become equivalent to a category 1 hurricane on the Saffir-Simpson hurricane scale (SSHS) with 1-minute sustained wind speeds of 120 km/h (75 mph). Over the next 12 hours, the system developed a 17 km cloud-filled eye on visible imagery, while the system's forward motion started to slow down as it entered a weak steering environment with the upper-level ridge of high pressure to the north of the system weakened and a subtropical ridge of high pressure developed to the south of the system.

The system continued to intensify and began to re-curve toward the west on December 16; at 18:00 UTC (07:00 UTC+13, December 17) the JTWC reported that Evan had reached an intensity of 185 km/h, which made it equivalent to a category 3 hurricane on the SSHS.

Early on December 17, the JTWC reported that Cyclone Evan had reached its peak intensity with 1-minute windspeeds of 230 km/h (145 mph), which made it equivalent to a category 4 hurricane on the SSHS. During that day Evan started to gradually weaken as it moved around the coast of the Fijian island of Viti Levu. With RSMC Nadi reporting by 18:00 UTC (07:00 UTC+13, December 18) that the system had weakened into a category 3 severe tropical cyclone.

By December 19, wind shear from the northwest had exposed the system's low level circulation center completely, pushing the bulk of convection and thunderstorm activity about 120 km to the southeast of the center. Evan had also moved into cooler sea surface temperatures, below 27 °C (81 °C), so evaporation and thunderstorm development had waned, leading to falling cloud heights because of less moisture.

Later that same day, RSMC Nadi reported that Cyclone Evan had weakened below cyclone intensity and declassified it as a tropical cyclone, before the JTWC issued their final warning later that day as the system started to transition into an extratropical cyclone. Over the next couple of days the remnant low continued moving southwards and moved below 25°S and into the Wellington tropical cyclone warning centre's (TCWC Wellington area of responsibility. During December 21, the system started to move towards the southwest as it directed a moist tropical airmass onto the North Island during the next day. The remnants of Evan were last noted by TCWC Wellington during December 25.

Preparations and impact
Severe Tropical Cyclone Evan impacted the island nations of Wallis and Futuna, Samoa, American Samoa, Niue, Tonga, Fiji and New Zealand, with 14 deaths reported and total damages estimated at over. As a result of its impact on the island nations, the name Evan was subsequently retired, from the list of names for the region by the World Meteorological Organization.

Fiji
On December 10, the FMS issued heavy rain warnings for parts of Fiji, as the trough of low pressure associated with the system, was bringing heavy rain and squally thunderstorms to parts of Fiji which they warned could lead to flash floods in parts of the archipelago. These warnings were subsequently cancelled during the next day as the system moved away from Fiji, however they started to note that the global numerical weather guidance products were agreeing on the depression, re-curving as a tropical cyclone and to start directly impacting Fiji from December 16. During the next three days, the FMS issued calls for communities to be prepared, heed warnings and act responsibly, so that they could avoid "unnecessary loss of lives and properties", as Cyclone Evan was expected to be at least a Category 4 Severe Tropical Cyclone when it entered Fijian waters. From December 15 to 18, as the system approached and passed through the archipelago, the FMS issued various strong, gale, storm and hurricane-force wind warnings for Fiji.

Ahead of the system approaching and impacting the island nation, people were evacuated to emergency shelters. Fiji Airways (Air Pacific) announced they are suspending all flights to Savusavu, as well as the international flights from Nadi to Auckland and Brisbane on December 16.

Upon passing over Fiji, over 8,000 people were living in shelters, including many tourists. Although there were no initial reports of casualties, the storm brought considerable damage. Trees and power lines were down across the island group. In addition, flooding and structural damage was reported from resorts and homes.

Damage throughout Fiji amounted to FJ$169.9 million (US$108.8 million). Additionally, short-term economic losses related to the cyclone were estimated reach FJ$73.4 million (US$40.9 million).

Wallis and Futuna
Cyclone Evan affected Wallis and Futuna on two separate occasions while it was active, with the cyclone first affecting Futuna during December 11, before passing within 20 km of Wallis Island on December 15, and 70 km of Futuna Island during the next day. On December 11, Futuna Island recorded 186 mm of rainfall and wind speeds of up to 35 mph as Evan passed just to the north of the island. Ahead of the system affecting the French Territory for the second time, various warning alerts were issued for the two islands, with people were urged to prepare. As the system passed near Wallis island, wind gusts of up to 156 km/h were recorded, which were the highest recorded wind gusts on Wallis Island since records began in 1971. The cyclone passed through the French territory without any reported casualties, and while Futuna Island was spared any major damage, extensive damage was reported on Wallis Island.

Samoa
Cyclone Evan affected the independent state of Samoa between December 11 and 15, and was considered to be the worst tropical cyclone to affect Samoa, since Cyclone Val in 1991. After the system was named on December 12, the Samoan Deputy and Acting Prime Minister Fonotoe Pierre Lauofo, signed a Disaster Declaration which lasted for 48 hours and activated all disaster response provisions of the Samoan National Disaster Management Plan. During that day the Samoa Meteorology Division issued gale and storm force wind warnings and a hurricane watch for Samoa, while preparations for the system started with several people boarding up their homes. During the next day these preparations continued before the SMS issued a hurricane warning for Upolu, after marginal hurricane-force winds of 114 km/h were observed on Mount Fiamoe, Upolu.

The cyclone struck, causing widespread damage in the capital, Apia. Many of the roads were blocked by flood waters and downed banana trees. Evan also caused damage to Faleolo International Airport in Apia, where the departures lounge collapsed, forcing its temporary closure. As a result, Fiji Airways (Air Pacific) cancelled all flights to Apia for December 14 and 15, citing safety concerns. Wind gusts of up to 130 mph were reported. The storm destroyed houses and caused almost complete failures in the power and water supply systems. The Disaster Management Office reported that the Tanugamanono power plant was heavily damaged, and power might not be restored for up to two months in some areas. A water treatment plant near Apia was also reported destroyed. At least three deaths were reported after the storm, including two children who were in low-lying areas and drowned. Authorities expressed concern over about the fate of at least 7 people who are still missing, as well as up to 3,000 others now living in emergency shelters.

The US Ambassador to New Zealand and Samoa David Huebner confirmed the United States had provided NZ$60,000 to the Samoan Red Cross for relief operations. New Zealand authorities said they were also ready to provide financial aid, if the local government requests it. On December 15, they did provide NZ$50,000, as well as a P-3 Orion plane to search for eight missing fishermen. Two days later the New Zealand Foreign Affairs Minister Murray McCully announced an additional NZ$550,000 was to be made available to the Samoan government, as well as the Samoan Red Cross and any agencies on the ground that might need it. Five additional New Zealand Red Cross workers were also sent to support local efforts. The Samoan Parliament opened with a somber prayer session, as the legislators prepared to receive initial assessments of the economic damage wrecked by Evan. According to reports, the bill is expected to be at least NZ$200,000,000, and possibly rise as high as 300 million.

On December 17, Samoan authorities confirmed that the death toll reached 14, after rescuers abandoned the search for 10 missing sailors. In all, damage from the storm amounted to WS$465 million (US$204 million).

American Samoa
The Pago Pago National Weather Service Forecast Office issued a gale watch for all of American Samoa a day before the storm impacted the island. As Evan intensified and moved closer to the archipelago, hurricane warnings and flash flood watches were issued for Tutuila, Aunuu, Manua and Swains Island. On December 14, authorities announced that there had been no major damage or injuries after the passage of the storm.

Tonga
On December 12, the FMS issued a tropical cyclone alert for the Tongan Islands Niuatoputapu and Niuafo'ou as it was thought that Evan might cause gale-force winds over the islands within 48 hours. During December 14, the alert was cancelled as Evan was no longer predicted to pass close enough to the islands to produce gale force winds or any damage on either island.

New Zealand
During December 23, as Cyclone Evan's remnants moved towards New Zealand, TCWC Wellington issued Severe Weather Warnings for parts of Northland, Auckland and Coromandel as between 70 - 100 mm of rain expected to fall which could cause surface flooding. They also predicted that parts of New Zealand would see strong or gale-force winds and that the eastern coasts of Northland, might see large sea waves of about 3 - 4 m. During that day in parts of the Coromandel Ranges, over 100 mm of rain fell while in other parts of the warning area 25 - 50 mm fell while the system was blamed for creating foggy conditions that engulfed parts of the North Island, and led to over 100 flights being cancelled at Wellington Airport. On December 24, the threat of heavy rain, surface flooding, swells and strong to gale-force winds continued while a swimmer drowned in rough seas of Whiritoa beach. During that day heavy rain and the threat of flooding gradually eased, before the remnants were last noted during the next day.