A hydrogen gas fire, a signature of the overheating caused by induced currents, erupted at the Zion Nuclear Power Plant on April 3, 1994. Due to the great expense of operating without the necessary transformers, Commonwealth Edison planned to put a replacement transformer into service sometime after midnight April 16. As the date approached, the Sun, as seen in X-ray images taken by the Japanese satellite Yohkoh, ejected a large massive structure. Such structures are frequently associated with geomagnetic disturbances at Earth. Based on these observations, NOAA's Space Weather Operations raised the probability for geomagnetic storm conditions for April 16 and 17 to 55%. Personnel at Commonwealth Edison consulted in depth with NOAA staff during April 16 because of concerns about the possible disturbance and its effects on the new transformer. As a result, Commonwealth Edison decided that the risk to the transformer justified the cost of postponing the installation until April 17, when the disturbance was predicted to subside. The disturbance began Saturday evening and proved to be intense. Aurora could be seen as far south as Boulder, Colorado. By late Sunday, the severe storm level had declined and the new transformer was successfully installed.