CARACAS, Venezuela (AP) — A storm that has hurled rain on the southern Caribbean and the northern shoulder of South America was expected to hit Central America as a tropical storm over the weekend and eventually develop into a hurricane over the Pacific, forecasters said Thursday.

The fast-moving disturbance known merely as “Potential Tropical Cyclone Two” has been drenching parts of the Caribbean region since Monday without ever meeting the criteria for a named tropical

It was blowing past the northernmost part of Colombia on Thursday night and was centred about 455 miles (730 kilometres) east of Bluefields on Nicaragua’s Atlantic coast, according to the US National Hurricane Center. A hurricane watch was in effect from the Nicaragua-Costa Rica border to Laguna de Perlas in Nicaragua.

It was moving west at 20 mph (31 kph) and was projected to hit the Nicaragua-Costa Rica area as a tropical storm late Friday or Saturday.

The storm had maximum sustained winds of 40 mph (65 kph) — right at the edge of tropical storm force, through with ragged wind circulation, apparently due to its rapid advance westward. The Hurricane Center said that pace should be slowing.

The storm was expected to drop 3 to 5 inches (75 to 125 millimetres) of rain on parts of northern Colombia, then 4 to 8 inches (125 to 250 millimetres) on Nicaragua and Costa Rica, posing the threat of flash flooding.

Venezuela and several Caribbean islands closed schools as the storm approached over recent days.