Yesterday off the coast of Northern/Central California a classic coastal jet was observed on the Quickscat sea winds satellite. Here’s a composite image showing the jet (the gale-force winds indicated by the red and black flags).

The factors that influence coastal jet formation are numerous and somewhat complicated. However, the California coastal jet can generally be described as the interaction of the semi-permanent east Pacific high pressure system and the temperature-driven western US low-pressure system. For a good introduction to coastal jet formation, you can view this web-based mini-course on the MetEd site (registration required, but free).