At 1200 UTC on June 5, the disturbance developed a broad, low-level circulation, and was classified as Tropical Storm Allison, the first storm of the 2001 Atlantic hurricane season. Some intensification was projected, though it was expected to be hindered by cool offshore sea surface temperatures.[4] Due to the cold-core nature of the center, Allison initially contained subtropical characteristics. Despite this, the storm quickly strengthened to attain peak sustained winds of 60 mph (95 km/h), with tropical storm-force winds extending up to 230 miles (370 km) east of the center, and a minimum central pressure of 1000 mbar.[2] The storm initially moved very little, and the presence of several small vortices from within the deep convection caused difficulty in determining the exact center location.[5] Later in the day, several different track forecasts arose.