In winter, a tongue-shaped front develops at the southern entrance of the YS west of Cheju-do. From autumn to winter, the Cheju Warm Current water advances westward as a Ì-shaped tongue in the western area of Cheju-do, whereas part of the cold and fresher water in the Chinese coastal area extends southeastward in the form of a drooping pocket over the Changjiang Banks. Our knowledge about the frontal circulation in the southern YS is very limited due to a shortage of observed data. Episodic northward current bursts were observed in the northern trough of the front, but the bursts do not occur near and in the frontal zone. The persistent formation in winter of the tongue-shaped front may be closely associated with a balance between the wind-driven flow and the tide-induced residual flow on the western flank of the YS entrance [Lie et al., 2001]. Circulation models without consideration of tides simulate a northwestward mean flow along the western flank of the YS entrance. On the contrary, models with consideration of tides rather show a southeastward mean flow along the western flank. That is, the tide-enhanced bottom friction effectively blocks the penetration of the northwestward flow. We may sketch a cyclonic frontal circulation around the tongue-shaped front from a combination of piecewise information and observed features.