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Very intense tropical cyclone Hellen struck Madagascar at about 00:00 GMT on 31 March. Data supplied by the US Navy and Air Force Joint Typhoon Warning Center suggest that the point of landfall was near 15.3 S, 45.4 E. Hellen brought 1-minute maximum sustained winds to the region of around 240 km/h (149 mph). Wind gusts in the area may have been considerably higher.

According to the Saffir-Simpson damage scale the potential property damage and flooding from a storm of Hellen's strength (category 4) at landfall includes: Storm surge generally 4.0-5.5 metres (13-18 feet) above normal. Curtainwall failures with some complete roof structure failures on small residences. Shrubs, trees, and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors and windows. Low-lying escape routes may be cut by rising water 3-5 hours before arrival of the centre of the storm. Major damage to lower floors of structures near the shore. Terrain lower than 3 metres (10 feet) above sea level may be flooded requiring massive evacuation of residential areas as far inland as 10 km (6 miles). There is also the potential for flooding further inland due to heavy rain.

The information above is provided for guidance only and should not be used to make life or death decisions or decisions relating to property. Anyone in the region who is concerned for their personal safety or property should contact their official national weather agency or warning centre for advice.

This alert is provided by Tropical Storm Risk (TSR) which is sponsored by Crawford&Company and University College London (UCL).