Tropical Storm Erin formed Monday and is expected to become a major hurricane as it moves across the Atlantic Ocean, according to the National Hurricane Center, though the potential risks to the U.S. remain unclear.

The National Hurricane Center is tracking three systems across the Atlantic basin Monday, including one near the Cabo Verde Islands with a high chance of developing into a tropical depression or storm within hours.

Tropical Storm Erin formed just west of the Cabo Verde Islands on Monday, the National Hurricane Center announced.