Velocities in the flank of the HSS belonging to the coronal hole with an area of 8 × 10¹⁰ km². The velocities were determined at latitudinal displacements of 6° (yellow), 9° (orange), 12° (brown), and 15° (dark brown) to its latitudinal center. (a) Snapshots of the radial velocity profiles in the the flank, taken at 1 day (dotted), 2.25 days (dashed), and 3.5 days (solid lines) after the center of the coronal hole has crossed the central meridian. (b) Peak velocities ﹩{v}_{{\rm{p}}}﹩ of the HSS in the flank vs. the radial distance of the location of the peak velocity to the Sun.