Hurricane the storm is projected to escalate to a rare highest-level hurricane as it veers in the direction of Jamaica, bringing life-threatening rapid inundation and landslides.
The cyclone, which had wind speeds of up to 120 mph as of 06:00 GMT, is currently turning northwest in the Caribbean and is anticipated to make landfall by midweek, according to hurricane specialists.
Warnings of electricity outages and structural damage have been released as this storm brings up to thirty inches of rain and coastal flooding as high as 13ft above typical tides. "Find safe refuge immediately," residents have been told.
The cyclone is the 13th named hurricane in the current Atlantic season, which usually concludes in November.
A category five cyclone is the most powerful category, with sustained winds of at least 157 miles per hour.
Although this storm is set to reduce in intensity to a Category 4 storm before reaching Jamaica, meteorologists said there was "minimal real distinction in the general consequences" upon landfall, and that the cyclone will be "at least that intensity" when it impacts the country.
With tropical storm-level gusts and precipitation already expected well before it passes over Jamaica's central region - possibly even the capital, Kingston - advisories state that "preparations should be rushed to completion".
"An extended timeframe of damaging winds and torrential rain are underway and will cause severe and deadly sudden floods and numerous mudslides," urged meteorological officials.
The nation's leader Andrew Holness said: "I realize that there are countless citizens who are worried, who are extremely apprehensive, and rightfully so: you should be concerned.
"However the most effective method to address anxiety and any nervousness and concern is to be prepared."
Inhabitants are being instructed to secure their homes with protective bags and plywood sheets, and to accumulate essentials.
Warnings are also ongoing for parts of Haiti encompassing the primary urban center, the adjacent nation and eastern Cuba, where this storm is anticipated to bring comparable impacts by the middle of next week.
Rock slides currently triggered by the cyclone have caused two deaths in Haiti, according to emergency services.
Melissa is projected to cross Cuba by Wednesday before passing across the Antillas Mayores and out into the Atlantic.
By the time it arrives at Cuba, it is predicted to have reduced to a Category 3 hurricane.
While it is challenging to connect specific storms to environmental shifts, experts say it is making meteorological events more common and more intense.
Increased sea temperatures generate more moisture in the air, helping fuel the formation of storms.
Ahead of the commencement of this season's Atlantic storm period, meteorological authorities predicted higher-than-average occurrence, referencing heated marine conditions and potential enhanced seasonal rains around African coastal regions - where tropical systems typically originate.
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