The paper reports and discusses simulated statistics obtained by the synthetic storm technique, in the Po Valley, Northern Italy, on the interruptions (outages), due to rainfall, observed in contiguous (clock) periods of the day of duration T, with 1 min less than or equal to T less than or equal to 24 h. The results refer to a 32degrees slant path at 11.6 GHz, although the main conclusions are independent of carrier frequency and of site, and are based on a large experimental rain rate database (10.6 years of observation). The results can be used to assess the quality and unavailability of services of duration T during a day in earth-space communication systems affected by rain attenuation. A distinction is made and discussed between channel unavailability and service unavailability. The numerical results and the best fit and extrapolation formulas derived might provide a rough approximation to the same statistics at different elevation angles, clock intervals and carrier frequencies, for sites with the same climate of the Po Valley.