Most of the nation is now forecasted for 20 to 30 inches. It is going to make landfall as a Cat 5. Typically, the small wind field is helpful with these new Climate Changed Cat 5s, but with Jamaica being a small island it won't help much. Additionally, the mountainous terrain will see the higher winds that come with the higher elevation. Prog'd to hit Cuba as a Cat 3. Then the Bahamas and Bermuda as a hurricane.
This being the worst storm would be something as Hurricane Gilbert struck the island in 1988. Gilbert was the second lowest pressure hurricane on record in the Atlantic. The pressure in Melissa has been plummeting and is 9th lowest.