Late on August 20, the first reconnaissance plane entered the storm and found a minimum central barometric pressure of 1001 mb. The storm brushed the Leeward Islands, although the main thunderstorm activity remained to the north of the storm over the open ocean. Bonnie began to organize its broad circulation early on August 21, and within the next day the storm began to intensify. The storm began to look strong on satellite images with banding features over the north and west quadrants. The Hurricane Hunters aircraft found a minimum pressure of 987 mb and a nearly complete eyewall early on August 22, and as a result, the tropical storm was upgraded to hurricane status. Bonnie slowed in forward speed, coinciding with previous forecasts. Later that day, storm was upgraded to a Category 2 on the Saffir-Simpson Hurricane Scale, which occurred with a substantial 15 mb drop in 8 hours. At the same time, steering currents weakened with the dissipation of the high pressure system; this, combined with the effect of a nearby trough, caused the storm to turn in a more north-northwestward direction around the western periphery of an anticyclone to the east. Bonnie became a Category 3 storm, a major hurricane, at 1200 UTC the next day, reaching its peak winds of at the same time.