Helen

History

Tropical Cyclone Helen was the fourth named system of the 2007–08 Australian region season and the first cyclone in more than two decades, since 1985, to deliver gale-force winds to Darwin. Its origins lay in a weak low that formed over the Top End around 28 December 2007, supported by La Niña conditions and an active Madden–Julian oscillation. The low initially drifted within a trough, briefly deepening to 993 hPa on 31 December before increased wind shear disrupted it. Moving over the Joseph Bonaparte Gulf on 2 January, the system organised and reached gale strength on the morning of 4 January, when the Bureau of Meteorology named it Helen. A monsoonal westerly flow then steered it back east towards the coast, and it continued to strengthen, reaching Category 2 with ten-minute mean winds of 95 km/h and a central pressure of 975 hPa.

Helen crossed the coast near Channel Point at about 10:00 pm local time on 4 January, briefly developing an eye that broke down over land. It weakened to a tropical low within roughly 12 hours, tracked across the Gulf of Carpentaria late on 5 January, made a second landfall on Cape York Peninsula on 6 January, and was last identified there on 7 January.

Rainfall from Helen and its precursor generally totalled 100–200 mm across the Top End, with 174.6 mm measured at Darwin between 1 and 6 January. One man drowned when floodwaters swept his car into the Victoria River. Gusts reached 120 km/h near the landfall point and 102 km/h at Darwin, where about 1,500 trees fell and some 15,000 homes — around 60 per cent of the city — lost power. A 2–3 m surge occurred near Channel Point, and seven vessels were driven ashore in Darwin Harbour. Damage totalled A$1.3 million, plus about A$1 million in clean-up costs, and the name Helen was retired.

Sources: Bureau of Meteorology report Wikipedia