A westward-moving tropical wave could produce an area of low pressure in the tropical Atlantic late in the week of Aug. 18, the hurricane center said on Aug. 16. The center shows a 20% chance of storm formation over the next week.

The NHC said it currently expected Erin to become a Category 4 storm later Saturday but to eventually swerve away from the continental United States.

The hatched areas on the National Hurricane Center's tropical outlook map indicate "areas where a tropical cyclone — which could be a tropical depression, tropical storm or hurricane — could develop," said National Hurricane Center Deputy Director Jamie Rhome.

The National Hurricane Center is tracking two systems in the Atlantic basin, including Invest 98L, which could become a tropical depression before moving onshore in either Mexico or southern Texas.

Spaghetti models predict Erin will skirt the U.S. East Coast by hundreds of miles as it moves north through next week.