The nation's worst tornado outbreak occurred on April 3, 1974. I was working that day as a forecaster for the National Weather Service in Louisville, Ky. We were expecting a major tornado outbreak, and had issued a warning for our local area based upon radar indications.
Later that afternoon, about a half hour after the tornado warning was issued, we observed a thunderstorm approaching Standiford Field from the southwest. A lowered cloud base along the edge of the storm was clearly evident, but we did not see a tornado. The top floor of the terminal building offered an unobstructed view of the storm. As the lowered cloud base moved overhead, we first observed the funnel cloud forming and were able to even see small scale circulations within the descending vortex.
Suddenly, an instrument shelter, which was bolted to a rooftop deck, collapsed on its side in front of our window. The tornado circulation had reached the roof without a visible funnel. We briefly sought shelter, then crossed the office to look towards the City of Louisville. The tornado was now clearly visible on the ground and was racing northeast into the densely populated city. An I-beam, ripped from the rooftop and thrown onto a car in the adjacent parking lot, marked the beginning of a trail of damage affecting 900 homes and causing millions of dollars of property loss.
This tornado was one of 148
twisters recorded during the outbreak. For me, it was the most
spectacular, since it was the first tornado I witnessed and the
only one I have viewed from such a perspective.