Preliminary results are presented on the nature of a distinct class of sub-km high latitude irregularities which can create localized regions of near saturated VHF and fairly intense UHF scintillations in the nighttime auroral F-region. The unique feature of this class of irregularities is that it is associated not with large scale (several tens of km) organized density gradients in the F-region but with velocity shears with shear gradient scale lengths ~10km. The presence of velocity shears was established by EISCAT ion drift measurements, continuous STARE measurements of electron drift and the in-situ ion drift measurements from the HILAT satellite. Analytical and numerical simulation studies of velocity shear driven Kelvin-Helmholtz type plasma instabilities are necessary to elucidate the generation mechanism of this class of irregularities.