21.   An upper-level low pressure trough will move in from the east on late Tuesday or Wednesday.

22.   At the same time a very weak low pressure trough is traversing Puerto Rico causing widely scattered light rain showers over the Virgin Islands and Puerto Rico.

23.   At the same time a low pressure trough just east of the leeward islands is competing as a rival force in the caribbean.

24.   For Wednesday it appears that less showers and thunderstorms will occur as the low pressure trough finally moves east away from the local area.

25.   However in the upper levels ... A fast moving low pressure trough is located just northwest of Puerto Rico, destabilizing the atmosphere.

26.   Low pressure trough from north coast of Hispaniola northeast across Atlantic to move east into Mona Passage.

27.   Meanwhile, a low pressure trough a few hundred miles east of the Leeward Islands was moving westward.

28.   On Wednesday there will be a weak low pressure trough sinking southward from northern latitudes that is expected to reach Puerto Rico and the U.S. Virgin Islands.

29.   Puerto Rico and U.S. Virgin Islands waters Synopsis ... A low pressure trough east of the Bahamas to Bermuda will move south tonight and Sunday.

30.   The situation will be magnified tonight as an upper level low pressure trough moves into the eastern Caribbean from the west producing more cloudiness and light rain showers.