The main features of ionospheric-geomagnetic storms and their probable causes are reviewed. Disturbances in short-wave radio propagation during such storms are discussed. The principles of short-term prediction of ionospheric-geomagnetic storms are summarized and all kinds of Izmiran's forecasts are described. The application of these forecasts and current ionospheric data to calculation of usable radio propagation frequencies is explained. This Manualiis of interest to radio-communication operators as well as to geophysicists dealing with this field of science.