Mystery Clouds Over Pennsylvania

Weather is often violent but usually predictable. Of course, we repeatedly mock forecasters for missing daily prognostications, but they point -- with solid evidence -- to records showing increased accuracy in their work.

From time to time, however, a weather event occurs which is not only unpredictable but unexplainable. One such was reported 28 July 1874 in the vicinity of a valley town called Mill Run, western Pennsylvania. Countless people watched as a weird black storm cloud, tinged with a reddish hue, slowly gathered from the southwest. Even more strange was the appearance from the opposite direction of a second, similar mass. Lightning intensified as the two frightful forces of nature came together. It was said as they collided and merged, the ground shook and the atmosphere was a tumult of fireworks for half a minute without diminishing. Then the electricity played itself out -- and the rains came. It was the heaviest downpour anyone could remember. Within minutes, the valley was awash in a torrential flood. Some 150 people drowned, as did untold head of cattle. Bridges and other structures were carried away.

A severe thunderstorm is intimidating to anyone. When storms meet head-on, even veteran meteorologists take notice.