Hours after being classified a tropical depression, the convective structure of the system deteriorated, a sign of a weakening storm; however, nearby oil rigs indicated a gradual increase in winds. Later on August 9, several rigs reported tropical storm-force winds – winds greater than 39 mph (63 km/h) – and the NHC estimated that the depression strengthened into a tropical storm. Operationally, however, these winds were considered to be related to local convective activity rather than the storm itself and it was not considered to be a tropical storm until post-storm analysis. As such, it was not named and is officially classified as "Unnamed Tropical Storm." Additionally, the strongest winds were located well away from the center of circulation, a signature of subtropical cyclones.