User:Jason Rees/Uma

Cyclone Uma was a powerful tropical cyclone that became one of the worst natural disasters in the history of Vanuatu.

Meteorological history
During the opening days of February 1987, the South Pacific Convergence Zone was well defined and extremely active, with various areas of low pressure located along the trough, as it extended westwards from the Samoan Islands across Tuvalu towards Australia. On February 3, Uma's precursor tropical depression developed along this trough of low pressure within the Australian region about 410 km to the south of Honiara in the Solomon Islands. At this stage, the depression had a broad circulation and was located within a favourable environment for further development, with inflow and outflow channels evident in satellite imagery. At around this time, an area of high pressure moved into the Tasman Sea, which caused large pressure rises in the Tasman and Coral Seas as well as along the Australian East Coast. This had the effect of increasing the easterly winds and provided extra low level cyclonic vorticity around the southern edge of the depression.

Over the next day, the system continued to develop as it moved south-eastwards across 160&deg;E and into the South Pacific basin, before the United States Joint Typhoon Warning Center (JTWC) initiated advisories on the system and designated it as Tropical Cyclone 13P. This was followed during February 5, by the Fiji Meteorological Service (FMS) who reported that the depression had developed into a tropical cyclone and named it Uma. Over the next day, the newly named system rapidly intensified and developed a broad and ragged eye, before the FMS reported that Uma had attained hurricane intensity, with estimated 10-minute sustained wind speeds of 70 kn. At this stage, the system was located about 175 km to the west of Espiritu Santo and had become slow moving, with its future movement hard to predict. During February 6, Uma continued move south-eastwards towards Vanuatu and intensify, before the JTWC reported that the system had peaked with 1-minute sustained wind speeds of 75 kn which made it equivalent to a Category 1 hurricane on the Saffir-Simpson hurricane wind scale. This was followed by the FMS who reported that Uma had peaked with 10-minute sustained wind speeds of 90 kn, which made the system a Category 4 severe tropical cyclone on the Australian tropical cyclone intensity scale.

During February 7, Uma entered an area of strong north-westerly winds, which increased the vertical wind shear over the system and caused it to start weakening. During that day, the system gradually weakened as it passed within 30 nmi of Port Vila on the island of Efate, before it passed near or over the islands of Erromango and Tanna. Uma subsequently rapidly weakened as it accelerated south-eastwards and started to interact with the newly named Tropical Cyclone Veli. Uma subsequently weakened below tropical cyclone intensity during February 8, before its remnants combined with Veli to form a broad complex area of low pressure to the south of Fiji. This area of low pressure subsequently transitioned into an extratropical cyclone and maintained gale-force winds, as it slowed down under a low-level easterly flow and upper westerlies. The combined area of low pressure subsequently dissipated in a baroclinic zone near Raoul Island on February 11.

Vanuatu
Uma impacted Vanuatu between February 6 – 8, 1987 where it became the first major tropical cyclone, to impact the island nation since Severe Tropical Cyclones Eric and Nigel in January 1985. It was responsible for 48 deaths, widespread damage which was estimated at around US$25 million and an economic loss of US$ 72 million. After Eric and Nigel had impacted the island nation, the Government of Vanuatu started to review their disaster management arrangements and decided to introduce a new disaster management plan with support from the United Nations. The new plan was developed and approved by the Government at the end of 1985 on a co-coordinated basis, with involvement from local and national government agencies as well as non-government organizations. The plan placed a range of responsibilities on the Government at all levels and established a new national disaster management office during 1986, which was responsible for the development and maintenance of disaster preparedness arrangements. Over the next year, the NDMO established various regional and area disaster committees, managed certain aspects of the recovery from Eric and Nigel, promoted general disaster preparedness and prepared information to issue to the public in the event of a major disaster.

Ahead of the 1986-87 tropical cyclone season starting, the NDMO performed various checks to ensure that counter-disaster arrangements were in place and reminded Government departments of their responsibilities under the National Disaster Plan. However, Government departments did not respond to NDMO's reminders about preparedness or submit their state of readiness, as required by the disaster plan on November 1. Ahead of Uma impacting the island nation, the Vanuatu Meteorological Service in conjunction with the FMS issued gale and hurricane warnings, by telephone and telex channels, as well as via Radio Vanuatu. However, several of these warnings were ignored, while some individuals, agencies and departments used the lead time provided by these warnings to good effect. In particular, the Vanuatu Mobile Force evacuated people from exposed and low-lying areas, into the shelter of strong school buildings prior to the cyclone's impact.

As Uma moved south-eastwards parallel to the axis of Vanuatu, it caused high seas, heavy rain and gale to hurricane force winds to be reported on various islands. The island of Efate was the worst impacted island, as Uma's eyewall passed directly over the island during February 7, where a minimum pressure of 957 hPa was recorded and sustained winds of 90 kn were estimated to have occurred. The islands of Erromango, Tanna and Aneityum were thought to have experienced either storm force or marginal hurricane force winds.

Aftermath
As a result of the impact on Vanuatu, the name Uma was later retired from the South Pacific lists of tropical cyclone names. When news of the disaster reached the French territory of New Caledonia, the French authorities reversed a decision to not provide any financial support for the island nation during the year and offered aid.