Laboratory experiments have suggested that the separation of a coastal
surface current from a cape of radius of curvature rho in a system ro
tating with Coriolis parameter f occurs when rho < u/f where u is the
characteristic flow speed of the current. Using an inviscid, reduced g
ravity model in the limit of rho large compared to the current width,
separation criteria are derived for various coastal currents of unifor
m potential vorticity. In this model, separation occurs when centrifug
al forces at the cape raise the density interface bounding the current
to the surface. For a current bounded on the offshore edge by a densi
ty front, the critical radius of curvature rho(c) is approximately tha
t found in the laboratory. For a current bounded by a zero-velocity co
ntour, the expression for rho(c) must be multiplied by a factor of W/R
, where W is the upstream current width and R is the Rossby radius.