 As the cyclone moved northwestward along the southern periphery of the Azores High, it began a period of rapid deepening in which a "pinhole" eye became distinguishable on satellite imagery; on this basis, Danielle was upgraded to a hurricane at 1200 UTC on August 25. At the time, Danielle was a compact system, with tropical storm force winds spanning only 115 miles (185 km) from the center. Although the NHC was fairly certain that the storm would continue west-northwestward, a veer north or south of the forecast track seemed plausible due to the influence of an upper-level low to the west-northwest of Danielle. Nonetheless, the storm continued its west-northwest track. At 0600 UTC on August 26, Danielle attained its maximum sustained wind speed of 105 mph (165 km / h), one of four peak intensities. Although the eye became obscured and southeasterly vertical wind shear increased late on August 26, the National Hurricane Center did not indicate weakening and instead predicted that Danielle would reach winds of 120 mph (195 km / h) by late on August 27. Early on August 27, a United States Air Force reconnaissance aircraft flight reported surface winds of 80 mph (130 km / h), though post-analysis indicates that the intensity of the storm was underestimated.
