  We have obtained deep HI observations in the direction of 22 continuum
sources without previously detected cold neutral medium (CNM). 18 CNM clouds
were detected with the typical HI column density of $3\times10^{18}$ cm$^{-2}$.
Our surprisingly high detection rate suggests that clouds with low HI column
densities are quite common in the interstellar medium. These clouds appear to
represent an extension of the traditional CNM cloud population, yet have sizes
in hundreds to thousands of AUs. We present properties of the newly-detected
CNM sample, and discuss several theoretical avenues important for understanding
the production mechanisms of these clouds.
