Measurements of near-bottom velocity profiles in 85 m water depth during a storm on the continental shelf off northern California using the GEOPROBE tripod in December 1979 provided estimates of shear velocities, and roughness lengths, z0 when the near-bottom velocity profiles were logarithmic. These estimates agree within 90% confidence intervals with values computed from a simple near-bottom combined wave-current model that includes movable bed effects. The reasonably good comparison between model and profile estimates of suggests that such models can be used to predict bed shear stresses (or shear velocities) under combined flows of waves and currents typical of stormy conditions on continental shelves if stratification corrections to the velocity profile resulting from suspended sediment are small. The repeated occurrences of storms of similar intensities and wind velocities during the winter months off northern California suggest that the resultant high bottom stresses due to the combined effects of waves and currents are major factors in controlling the distribution of surficial sediment on the central portion of the northern California shelf. ¿American Geophysical Union 1987