KOMU, the NBC affiliate for Columbia, MO, was evacuated Sunday because of fears the broadcast tower might fall during the latest storm to hit the area.
Engineers, concerned by high winds along with a build-up of heavy snow on the tower, ordered the evacuation of the station just before 10:00 a.m.
Shortly after Noon, the station tweeted the all-clear saying, “We are happy to report KOMU has been given the all-clear and we are all safely back in the building.” Viewers saw no interruption on-air. The station was airing network programming during the evacuation.
>UPDATE: Chris Swisher, KOMU manager of broadcast operations told TVSpy, “The issue was that the guy lines (the cables that hold the tower upright) had accumulated a wet sticky snow that in essence created an airfoil around the cables that would move in the wind. As the wind speed and direction was perfect, the cable would flop or gallop in the wind at or near the resonant frequency of the length of the cable. This in turn shook the tower and caused the structure to become unstable. We used a rope and a piece of construction equipment to change the resonant frequency of the guy line to make it non-resonant.”
Swisher said the tower had done this once before more than 14 years ago. The station plans a full inspection of the structure in the Spring.