The National Weather Service upgraded Tropical Depression Ernesto to a tropical storm Thursday as the front reached winds topping at 50 mph.

"Tropical Storm #Ernesto advisory 5 issued. Depression strengthens into fifth tropical storm of the season," the National Hurricane Center tweeted at 4:39 p.m. Thursday EST.

Ernesto is moving at 22 mph in a westerly direction, with the storm expected to be near the Windward Islands by late Thursday or early Friday, according to the National Weather Service's advisory on the tropical storm.

The upgrading of Ernesto from a tropical depression to a tropical storm caused a ripple effect across the Caribbean.

Due to the upgrade, Barbados, St. Vincent and the Grenadines, and the Dominican Republic are now under a tropical storm warning. The countries were previously under a tropical storm watch.

Also upgraded to a tropical storm warning are St. Lucia, Martinique and Guadeloupe.

The warning "means that tropical storm conditions are expected somewhere within the warning area ... in this case within the next 12 to 24 hours," the National Weather Service said.

Tropical storm-force winds are expected to be felt within 115 miles of Ernesto's center, mainly to the north and northeast, according to the NWS.

The storm is expected to bring rainfall of two to three inches in the warning area, with a maximum of five inches for the Windward Islands through Friday.

The National Weather Service said it would issue another advisory on Ernesto at 8 p.m. Atlantic Standard Time, with a more complete advisory at 11 p.m. You can get those updates here.