A number of closely spaced airborne radiometer flights over the entire Keweenaw Current in Lake Superior suggest that bathymetry plays a major role in determining the overall features of the current. The crosscurrent surface temperature variations are correlated over long‐current distances of kilometers only in a loose sense, and the crosscurrent fine structure is essentially uncorrelated over the same distance. The crosscurrent temperature variations are often dominated by very sharp fronts, which seem to become unstable and spawn meanders along their outer edg