I cannot over stress the importance of divergence and convergence of air. Developing winter storms are marked on maps by a low pressure at the surface. Air is moving in to 'fill-in the low pressure', this is convergence. By converging air molecules over a given region, we are adding molecules to our column and so the pressure should increase. Because divergence is occurring above the surface low.
Divergence removes air molecules from our column of air, thus dropping the pressure at the surface.
Thus, if the upper level divergence is removing molecules faster than the low level convergence the surface low pressure will decrease. This decreases the surface pressure which increases the pressure gradient force, which increases the wind speed and causes the air to rush in faster towards the low pressure center. Questions for Thought.