The National Hurricane Center (NHC) is monitoring two areas to watch for tropical development behind Hurricane Erin as the Atlantic Ocean's Main Development Region roars to life.

Tropical Storm Dexter is forecast to strengthen in the north Atlantic Ocean, according to the National Hurricane Center.

Forecasters are tracking a new disturbance in the Atlantic Ocean as Hurricane Erin, a Category 5 storm, undergoes an eyewall replacement cycle, according to a Saturday night update from the National Hurricane Center.

Hurricane watchers are eying systems in the Atlantic basin. One has a medium chance of developing later this week.

They are the hurricanes of legend, the bowling balls that cross the entire Atlantic Ocean, menaced ships of yore and make the long, curved lines on the hurricane charts. Cape Verde storms, named for the group of islands about 450 miles (725 kilometers) off the west coast of Africa,

Erin developed in the eastern Atlantic, moving westward from the Cabo Verde Islands at about 20 mph (32 km/h). Infrared sensors on NOAA's GOES-19 satellite reveal colder cloud tops and deep convection near the center — signs of a strengthening system feeding on warm ocean waters.

Although the storm is expected to stay offshore, it will produce dangerous surf conditions for much of the Atlantic Coast this week, forecasters say.

Reports from NOAA and Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds have increased to near 75 mph. Steady to rapid strengthening is expected during the next two to three days, and Erin is forecast to become a major hurricane this weekend.