The West Wind Drift feeds both the California and Alaska Currents, providing a pathway for exchange between the subarctic and subtropical gyres. Its bifurcation at the eastern boundary is known qualitatively but not particularly quantitatively. The relative proportions of waters returning poleward and those continuing equatorward is a matter of speculation due to a relatively sparse observational base incapable of resolving the space-time structure of the eastern boundary current formation. Seasonal and interannual changes in stratification in a broad region off the Pacific Northwest coast are recognized, but their causes and links to flow variation are largely unknown. Seagliders will operate year-round, occupying repeated hydrographic sections across the northern reaches of the California Current system. These measurements will characterize the seasonal evolution of the eastern boundary current system off the Washington coast.