Follow CBSMIAMI.COM: Facebook | Twitter

MIAMI (CBSMiami) – Tropical Storm Isaac has picked up speed as it heads toward the Caribbean Sea.

READ MORE: Finding A Mental Health Counselor Can Be 'Challenging And Overwhelming'

At 11 p.m., the center of the storm was about 220 miles east of Dominica.

Isaac is moving toward the west near 20 mph, and this general motion with a decrease in forward is expected to continue through the weekend.

On the forecast track, Isaac is forecast to move across the central Lesser Antilles and into the eastern Caribbean Sea on Thursday, and then move across the eastern and central Caribbean Sea through the weekend.

Data from a NOAA Hurricane Hunter aircraft and satellite-derived wind data indicate that the maximum sustained winds have decreased to near 50 mph with higher gusts.

A gradual decrease in the winds is forecast during the next 48 hours.

READ MORE: Florida Governor Ron DeSantis Giving Green Light To Budget Items

Tropical-storm-force winds extend outward up to 175 miles to the north of the center.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT

A Tropical Storm Warning is in effect for…
* Martinique
* Dominica
* Guadeloupe

A Tropical Storm Watch is in effect for…
* Antigua
* Montserrat
* St. Kitts and Nevis
* Saba and St. Eustatius
* St. Martin and St. Maarten

Isaac is expected to produce up to 4 inches of rain, with isolated amounts up 8 inches, across Martinique, Dominica, and Guadeloupe, 1 to 2 inches with isolated amounts to 4 inches across Puerto Rico and the southern United States Virgin Islands, with up to an inch anticipated across the remaining Windward and Leeward Islands.

Tropical storm conditions are expected on Martinique, Dominica, and Guadeloupe early Thursday. Tropical storm conditions are possible within the tropical storm watch area on Thursday.

MORE NEWS: Biden Invokes Defense Production Act To Address Infant Formula Shortage, Among Other Actions

Some coastal flooding is possible in areas of onshore winds. Near the coast, the surge will be accompanied by large waves.