Most of us are familiar with the term downburst or microburst. These occur when a thunderstorm cell collapses rapidly.
We are probably most familiar with the term microburst. A microburst occurs when a single-cell thunderstorm collapses. Just prior to the collapse the storm has a column of air that is rising rapidly often to heights of 50,000 to 60,000 feet above the ground. When the storm suddenly collapses this column of air stops moving upward and begins to move back down to the ground. When the column of air strikes the ground it moves radially outward in all directions from the contact location with the ground (like the spokes on a bicycle wheel) creating wind damage in all directions.
The same thing can occur with a multi-cell or line of thunderstorms when one cell of the system collapses suddenly. In these cases the other cells of the storm system cause the collapsing air to move in the direction of the storm system as they continue down towards the earths surface. As a result these damaging winds tend to all move in one direction upon ground contact instead of radially outward in the single-cell storm. It would be like sliding down a slide and then shooting off the end once you get to the bottom.
The damage is usually short lived in width and distance from the events I have seen, although, the damage at the point of impact with the ground is often extensive.
