The eigenmode equation describing ballooning collisional drift instabilities is analysed in the presence of a radially varying poloidal velocity. The instability is found to be stabilized by an H-mode-type velocity profile. The radial mode structure is found to be more extended than its conventional localized Gaussian form. Electron Landau damping (contrary to the usual ion Landau damping of the corresponding slab problem) is conjectured as the possible sink of the outgoing energy.