MEMPHIS, TN (WMC) - An outflow boundary, or a gust front as it is sometimes called, is formed when rain-cooled air from the downdraft of a thunderstorm hits the ground and spreads out ahead of a storm or in the direction that the lower level surface winds are flowing.
This outflow boundary will provide a sudden gust of cooler air for those in its path.
The outflow boundary can often times be detected on radar. As it moves along it can lift insects, dust, and debris along its leading edge making it visible as a thin line on the reflectivity setting of a Doppler radar.
It can sometimes be seen more clearly on the velocity or wind setting of a radar.
The boundary can also provide lift to warm moist air in advance of it triggering a thin line of brief precipitation over an area as it moves through.
If the atmosphere unstable enough and there are abundant heat and moisture at the surface, it can give that enough lift to create another thunderstorm cell.
In most cases, the outflow boundary just provides a brief cool breeze for those in its path.