We consider the phenomena observed in the microwave radiation emitted by the Sun during a twohour period, which precedes the time when the coronagraph records coronal mass ejections. The data of 24-h patrol observations of centimeter-and decimeter-wave radiation in 1998 and 2003 are used, as well as the data about individual events in January 2005 and December 2006. Temporal characteristics of the phenomena and the spectral composition of sporadic components of the solar microwave radiation are analyzed. The statistical relation between the characteristics of sporadic radio waves, which are observed within the above-mentioned interval, and the parameters of coronal mass ejections have been found.