User:Jason Rees/Uma
South Pacific cyclone in 1987
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Severe Tropical Cyclone Uma was a powerful tropical cyclone that significantly affected Vanuatu.
 Cyclone Uma near peak intensity on 7 February | |
| Meteorological history | |
|---|---|
| Formed | 4 February 1987 |
| Extratropical | 8 February 1987 |
| Dissipated | 10 February 1987 |
| Category 4 severe tropical cyclone | |
| 10-minute sustained (MetService) | |
| Highest winds | 165 km/h (105 mph) |
| Lowest pressure | 940 hPa (mbar); 27.76 inHg |
| Category 1-equivalent tropical cyclone | |
| 1-minute sustained (SSHWS/JTWC) | |
| Highest winds | 150 km/h (90 mph) |
| Lowest pressure | 963 hPa (mbar); 28.44 inHg |
| Overall effects | |
| Areas affected | Vanuatu |
| IBTrACS | |
Part of the 1986–87 South Pacific cyclone season | |
Meteorological history
Tropical storm (39–73 mph, 63–118 km/h)
Category 1 (74–95 mph, 119–153 km/h)
Category 2 (96–110 mph, 154–177 km/h)
Category 3 (111–129 mph, 178–208 km/h)
Category 4 (130–156 mph, 209–251 km/h)
Category 5 (≥157 mph, ≥252 km/h)
Unknown
Extratropical cyclone, remnant low, tropical disturbance, or monsoon depressionDuring the opening days of February 1987, the South Pacific Convergence Zone was well-defined and extremely active, with various areas of low pressure occurring along the trough, as it extended westwards from the Samoan Islands across Tuvalu towards Australia.[1] On 3 February, Uma's precursor tropical depression developed along this trough of low pressure within the Australian region, about 410 km (255 mi) to the south of Honiara in the Solomon Islands.[1][2] 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.[1] 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.[1][3] This had the effect of increasing the easterly winds and providing extra low-level cyclonic vorticity around the southern edge of the depression.[1]
Over the next day, the system continued to develop as it moved south-eastwards across 160°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.[2][4] This was followed on 5 February by the Fiji Meteorological Service (FMS), which reported that the depression had developed into a tropical cyclone and named it Uma.[1] 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 130 km/h (80 mph).[1][2] At this stage, the system was located about 175 km (110 mi) to the west of Espiritu Santo and had become slow-moving, with its future movement hard to predict.[1][2] During 6 February, Uma continued to move south-eastwards towards Vanuatu and intensify, before the JTWC reported that the system had peaked with 1-minute sustained wind speeds of 140 km/h (85 mph), which made it equivalent to a Category 1 hurricane on the Saffir-Simpson hurricane wind scale.[2][4] This was followed by the FMS, which reported that Uma had peaked with 10-minute sustained wind speeds of 165 km/h (105 mph), which made the system a Category 4 severe tropical cyclone on the Australian tropical cyclone intensity scale.[2][5]
On 7 February, Uma entered an area of strong northwesterly winds, which increased the vertical wind shear over the system and caused it to start weakening.[1][6] Throughout the day, the system gradually weakened as it passed within 55 km (35 mi) of Port Vila on the island of Efate, before it passed near or over the islands of Erromango and Tanna.[1] Uma then weakened rapidly as it accelerated south-eastwards and started to interact with the newly named Tropical Cyclone Veli.[1] On 8 February, Uma weakened below tropical cyclone intensity, before its remnants combined with Veli to form a broad, complex low-pressure area to the south of Fiji.[2][6] 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.[1][6] The combined area of low pressure dissipated in a baroclinic zone near Raoul Island on 11 February.[7]
Preparations and impact
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.[8] 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.[8] 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.[8] 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.[8] 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.[8]
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.[8] 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.[8] 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.[8][9] However, several of these warnings were ignored, while some individuals, agencies and departments used the lead time provided by these warnings to good effect.[8][9] 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.[8]
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 (28.26 inHg) was recorded and sustained winds of 165 km/h (105 mph) 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.[1]
Aftermath
As a result of the impact on Vanuatu, the name Uma was later retired from the South Pacific lists of tropical cyclone names.[12] 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.[13]
See also
- Cyclone Anne - The fourth major tropical cyclone to affect Vanuatu between 1985-1990
- Cyclone Bola - The fifth major tropical cyclone to affect Vanuatu between 1985-1990