Here’s a quick plot from one of Sounder’s laps around the inshore box today (14 Sep 2017).  The first leg goes along the 20 m isobath from the NW corner to the southwest corner.  The upper 10 m of water is headed onshore (red) at ~20 cm/s, and the lower 10 m of water is headed offshore at ~ 20 cm/s.  Classic cross-shore exchange?  You be the judge.  More puzzling is the lack of exchange (or much flow at all, green being ~0 cm/s) along the 10 m isobath….