A non-tropical area of low pressure formed about 150 miles (240 km) south of Wilmington, North Carolina, on June 13 and began to be monitored for potential tropical development, although chances of such were initially deemed low.[39] Overnight however, the system rapidly organized with ample deep convection and a small core forming.[40] At 15:00 UTC the next day, the National Hurricane Center (NHC) initiated advisories on the system and designated it as Tropical Depression Two.[41] The depression accelerated northeastward in the following hours, with convection briefly decreasing as a result of wind shear and the circulation becoming exposed, as seen on visible satellite images.[42] Twelve hours later, the depression strengthened into Tropical Storm Bill as the storm developed a more defined cluster of thunderstorms northeast of the center, while a scatterometer pass additionally confirmed the cyclone was producing gale-force winds.[43] Bill intensified on June 15 with convection becoming organized in a curved band pattern despite wind shear.[44] The storm reached its peak intensity by 15:00 UTC that day, with 1-minute sustained winds of 60 miles per hour (95 km/h) and a minimum pressure of 998 mbar (29.47 inHg).[45] Despite a tight core structure developing, dry air began wrapping into the southeastern section of the storm shortly after that time.[46] Strong wind shear then exposed and elongated the center of Bill to the southwest of the convection as it raced northeast at over 35 mph (56 km/h).[47] At 03:00 UTC on June 16, Bill transitioned into an extratropical cyclone.[48]