Case Study Intensity of Tropical Cyclone Ofa February

Tropical Cyclone Ofa in early February 1990 was a devastating event for several South Pacific nations (Fig. 5.10). The storm initially developed over Tuvalu on 27 January as a depression within the South Pacific Convergence Zone. It rapidly intensified to hurricane strength as it moved south southeast near the Samoan islands with sustained winds greater than 118 km h-1. Samoa was severely affected from 3 to 4 February. Winds became very destructive, lasting for almost 24 h, with rain continuous and heavy for a few hours longer.

The combination of furious winds, heavy rainfall and storm surge created an impact not encountered in Samoa in more than a hundred years. Huge waves and sea spray resulting from the storm tide flooded low-lying areas, reaching up to 10-15 km inland. Northern coasts of Upolu and Savai'i islands were worst hit, but the whole population was left in a state of terrible distress (Fiji Meteorological Service 1990). Roofs of houses were peeled away, walls knocked down, trees felled, and roads, bridges and power lines were badly damaged. Storm surge washed off and reshaped about 80% of the northwestern coastlines of the two main islands, adding to the widespread flooding caused by the torrential rainfall. Seven people perished, either swept away by giant waves or killed by flying debris. According to preliminary estimates of the damage by the media, TC Ofa cost Samoa about US$130 million.

The single island nation of Niue was also devastated. The central eye passed within 50 km of Niue during the late afternoon on 4 February. An excerpt from the tropical cyclone report by the Fiji Meteorological Service (1990) gives a graphic description of the storm's ferocity:

As the eye of Ofa passed close to Niue, destructive hurricane-force winds lashed the island for several hours. Gigantic sea waves resulting from storm surge swept over the northern and western coastal areas of the island and were reported to have reached several metres high. Virtually all landings to the sea were washed away or badly damaged by huge sea waves. There was considerable damage to hospital buildings, the island's hotel, roads, houses, churches, community halls and other facilities for the public. Due to the damage to power lines, electricity was out for about 24 hours. Most of the island's private water supply tanks were contaminated by salt water and declared unsuitable for drinking. Luckily, there was no loss of life or serious injury. The total loss from the cyclone was estimated at around US$2.5 million.

Continue reading here: Storm Surge and Sea Flooding Wind and Pressure Components

Was this article helpful?

+1 0