(Reuters) – Tropical storm warnings have been issued for western Cuba and northwestern Bahamas, the U.S. National Hurricane Center (NHC) said on Friday, as an area of low pressure over the northwest Caribbean Sea is expected to strengthen into a tropical cyclone.

The system is about 415 miles (670 km) south southwest of Havana, Cuba with maximum sustained winds of 40 miles per hour (65 km/hour), the Miami-based weather forecaster said.

A tropical storm warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours, according to the NHC’s website.