A powerful tropical disturbance moving off the coast of Africa threatened to become the 2018 hurricane season’s sixth-named tropical storm on Thursday, and a tropical wave located near the island of Hispanola in the Caribbean Sea could develop once it moves into the Gulf of Mexico, weather forecasters said.

The National Hurricane Center has already begun issuing advisories on what it calls “potential tropical cyclone six,” which is just off the west coast of Africa and was expected to bring heavy rains and gusty winds to the southernmost Cabo Verde Islands on Friday.

The system had maximum sustained winds of 30 mph and was moving west at 12 mph. Its central pressure was measured at 1007 mb. To be named, a cyclone must have sustained winds of at least 39 mph.

A tropical storm warning was issued for the islands of Santiago, Fogo and Brava and the Cabo Verdes.

In its 2 p.m. statement, the Hurricane Center said the disturbance was expected to begin a west to northwest movement over the next few days and should reach tropical storm strength today or tomorrow. The predicted track would take the storm out over the central Atlantic Ocean, where it is expected to become a hurricane.

If the storm is named it will be called Florence.

The system in the Caribbean is a tropical wave that is producing a large area of cloudiness and thunderstorms extending from Hispanola northeastward across the Caribbean and adjacent Atlantic waters.

Forecasts expect the system to move west-northwest, but it is not expected to develop immediately due to strong upper-level winds in the area. Once it reaches the Gulf of Mexico, conditions for intensification could improve.

The name after Florence is Gordon.