We present a relatively simple analysis of the gradient drift instability in barium clouds which includes the effects of both finite temperature and finite parallel length. It is found that short-wavelength modes are stabilized as the electrons redistribute parallel to the magnetic field and neutralize the charge imbalance set up by the instability. An analytical expression for the critical wave number for stabilization is given as well as numerical results. We discuss the application of these results to the structuring of barium clouds.