Hurricane Melissa has intensified into a Category 5 storm as it slowly approaches Jamaica, bringing the threat of destructive winds, life-threatening storm surge and catastrophic flooding.

The storm, which is packing sustained winds of 260 km/h, is centred about 205 km south southwest of Kingston and moving west at just 6 km/h. Its slow movement is increasing the risk of prolonged rainfall and severe flooding.

The Jamaican government has warned that conditions will deteriorate significantly through today and into tonight. Hurricane-force winds are expected to begin late today, with the worst conditions likely tonight and early Tuesday.

The slow pace of the storm means rainfall totals of 380 to 760 mm are expected in parts of Jamaica, with isolated totals reaching 1,000 mm. Forecasters warn of numerous landslides across mountainous areas and catastrophic flash flooding in river valleys and low-lying towns.

Storm surge heights along Jamaica’s southern coastline could reach 3 to 4 metres above ground level near and east of the point of landfall. These surges will be accompanied by large and destructive waves that are expected to inundate coastal communities and roadways.

Cuba is also preparing for severe conditions. Hurricane warnings are now in effect for the provinces of Granma, Santiago de Cuba, Guantanamo and Holguin. Eastern Cuba could see 250 to 380 mm of rainfall, with localised totals near 500 mm and extensive flooding.

A hurricane watch has been issued for the Turks and Caicos Islands and parts of the central and southeastern Bahamas. Tropical storm warnings are in place for Haiti and the Cuban province of Las Tunas. Authorities there are urging residents to complete preparations quickly before conditions deteriorate.

Melissa is expected to turn northwest later today and then accelerate northeastward from Tuesday, a shift that would bring it across Jamaica tonight into Tuesday, southeastern Cuba Tuesday night and the southeastern Bahamas on Wednesday. Even as it moves away, the storm will continue to generate large swells across the Caribbean with strong rip currents and hazardous surf.

Emergency officials across the region are urging residents to follow evacuation instructions and avoid attempting travel once winds increase. Forecasters warn that the combination of powerful winds, storm surge and extreme rainfall represents a life-threatening situation.

The National Hurricane Center is advising that preparations to protect life and property in Jamaica should now be complete. Those in eastern Cuba and the Bahamas are being urged to finish preparations today before tropical storm conditions make travel dangerous.