Tropical Storm the storm is predicted to escalate to a uncommon category five cyclone as it turns in the direction of the Caribbean island, bringing life-threatening rapid inundation and mudslides.
The cyclone, which registered wind speeds of up to 120 mph as of 06:00 GMT, is now shifting north-west in the Caribbean region and is expected to reach land by midweek, based on data from hurricane specialists.
Advisories of electricity outages and structural damage have been announced as Melissa produces up to 76cm of rain and coastal flooding as high as thirteen feet above typical tides. "Take cover without delay," inhabitants have been urged.
The cyclone is the thirteenth storm in the current Atlantic season, which typically ends in November.
A Category 5 storm is the strongest type, with sustained winds of at least 157 miles per hour.
Although this storm is set to reduce in intensity to a category four hurricane before arriving at Jamaica, experts said there was "very little practical difference in the general consequences" upon landfall, and that the cyclone will be "at least that intensity" when it strikes the country.
With tropical storm-strength wind and rainfall already expected ahead of it crosses central Jamaica - possibly even the city of Kingston - advisories state that "readiness efforts must be accelerated".
"A multi-day period of damaging winds and intense precipitation are underway and will cause severe and deadly rapid water accumulation and many landslides," counseled weather authorities.
The country's head of government the statesman commented: "I understand that there are many Jamaicans who are anxious, who are extremely apprehensive, and with good reason: concern is justified.
"Yet the best way to manage anxiety and any nervousness and worry is to stay ready."
Locals are being advised to protect their properties with sand barriers and timber panels, and to gather basic necessities.
Warnings are also in effect for areas in Haiti including the capital, Port au Prince, the adjacent nation and the eastern part of Cuba, where Melissa is expected to bring similar effects by the midweek period.
Rock slides presently generated by the hurricane have caused two deaths in Haiti, according to the nation's Civil Protection agency.
The hurricane is predicted to move across the island nation by midweek before traveling via the Antillas Mayores and entering the Atlantic Ocean.
By the time it reaches the Caribbean nation, it is forecast to have reduced to a Category 3 hurricane.
Although it is hard to connect particular meteorological occurrences to global warming, researchers say it is causing climate patterns more common and more severe.
Warmer oceans create additional humidity in the air, helping fuel the development of storms.
Before the start of this year's Atlantic hurricane season, weather organizations projected above-normal activity, referencing elevated ocean temperatures and possible enhanced seasonal rains around African coastal regions - where Atlantic storms typically originate.
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