From www.weather.com:
Tropical Storm Ernesto continues to slowly strengthen as of late Friday evening and The National Hurricane Center has now posted tropical storm warnings for the southwestern peninsula of Haiti. A tropical storm watch remains in effect for the island of Jamaica.
Satellite imagery continues to suggest strengthening of the system. Ernesto is moving west-northwest and this general motion is expected to continue through the weekend. There is still some uncertainty with the exact track and intensity of the storm. Currently an upper low out ahead of the storm is creating strong westerly shear in its future path, which would create unfavorable conditions to support the system. However, current forecast information indicates that these unfavorable conditions will lessen in time, leading to further development.
While the bulk of the heavier squalls will remain south of the Virgin Islands and Puerto Rico, a few outer bands will generate some heavier downpours and gusty conditions in these areas through Saturday. By Sunday, heavy squalls and gusty winds will begin to impact parts of Hispaniola and Jamaica. Ernesto may begin to threaten the Gulf of Mexico by early next week. For now, interests along the Gulf Coast states should simply monitor and be aware of the system. Stay tuned to The Weather Cannel's Hurricane Central for the latest updates.