Hur­ri­cane Melis­sa strength­ened in­to a ma­jor Cat­e­go­ry 4 hur­ri­cane, with the pos­si­bil­i­ty of in­ten­si­fy­ing to a Cat­e­go­ry 5 storm Sun­day night, un­leash­ing tor­ren­tial rain and threat­en­ing to cause cat­a­stroph­ic flood­ing in the north­ern Caribbean, in­clud­ing Haiti and Ja­maica, the U.S. Na­tion­al Hur­ri­cane Cen­tre said.

The weath­er agency added Melis­sa is like­ly to reach the south­ern coast of Ja­maica as a ma­jor hur­ri­cane late Mon­day or Tues­day morn­ing, and urged peo­ple on the is­land to seek shel­ter im­me­di­ate­ly.

“I urge Ja­maicans to take this weath­er threat se­ri­ous­ly,” said Ja­maican Prime Min­is­ter An­drew Hol­ness. “Take all mea­sures to pro­tect your­self.”