HOLT, Fla., Sept. 27, 2017–The low-pressure system in the Caribbean Sea has been upgraded by the National Hurricane Center to a tropical depression.

An Air Force Reserve Hurricane Hunter aircraft surveyed the storm this afternoon, and while it didn’t find a well-defined center, the NHC expects tropical storm conditions to affect Cuba and the northwestern Bahamas in the next 24-to-36 hours.

Environmental conditions are expected to be favorable for further development, and the system is likely to become Tropical Storm Philippe tonight or Saturday.

According to the NHC, the system is situated in a low-shear environment and over warm waters, so some slow strengthening is expected before the system reaches Cuba.

A faster northward motion is expected to begin tonight, followed by a faster motion toward the northeast on Saturday and Sunday.

The system will move across western Cuba late Saturday and move through the northwestern Bahamas Saturday night and early Sunday.

Data from the reconnaissance aircraft indicate maximum sustained winds are near 40 mph with higher gusts. A tropical depression becomes a tropical storm when sustained winds become 39 mph or higher, up to 74 mph.

This is the 18th storm of the 2017 Atlantic hurricane season.