In early December, a low moving to the west led to the formation of a broad surface trough to the east of the northern Lesser Antilles. With a strong ridge to its northeast, the trough tracked slowly westward, creating scattered convection and some turning. On December 8, convection began to continue with the trough and an upper-level low. Early on December 9, several tropical cyclone forecast models expected its development of tropical characteristics. The system, which included of a sharp trough with an area of gale force winds to its north, continued west through an area of warm sea surface temperatures. On December 10, a circulation developed within the system, though its convection had become unorganized and well-removed from the center. Wind shear from the south left the structure damaged, but convection increased closer to the center. With an low just south of the center, the National Hurricane Center classified it as Subtropical Storm Olga on December 11 while located about 55 miles (85 km) east of San Juan, Puerto Rico.