The storm slowly strengthened over the warm waters of the eastern Atlantic thereafter as it tracked west-northwest. Some dry air from the Saharan Air Layer continued to slow development on September 14 as Helene remained a low-end tropical storm. However, a bout of intensification took place on September 15 as shear diminished. The storm became much better organized with well-defined banding, and leveled off that evening at just under hurricane intensity. On the morning of September 16, the storm began to develop a ragged eye, and the storm strengthened to hurricane status. The intensity leveled off for a while as a marginal Category 1 hurricane, as the intensification was slowed by the presence of moderate wind shear despite the absence of significant dry air. Late that evening, the storm began to slowly intensify once again.