As a potent cold front pushed toward mid Missouri last evening, an arc of thunderstorms developed, moving southeastward at 30 mph or more. Ten minutes before the storms arrived, Columbia received a blast of wind that shook the trees, downing limbs and power lines. Local meteorologists reported wind gusts of 60-70 mph.
These destructive winds, which form a gust front, result from rain-cooled air which plummets through the thunderstorms and is deflected outward as it hits the ground. In isolated storms, this outflow boundary moves out in all directions, creating a circle of gusty winds around the thunderstorm. When storms are aligned on a front, as occurred last evening, the winds move out in advance of the storm wedge, their speed a sum of the downdraft and the movement of the storms themselves.
Outflow boundaries that move into the warm sector (ahead of the front) often ignite other thunderstorms as the cool air of the gust front undercuts and lifts this moist, unstable air. As a result, a line of scattered storms begins to develop ahead of the primary cold front.
