The problem of determining the outage probability in cellular systems where each of the desired signal and the cochannel interferers are lognormal shadowed and Weibull faded is considered. An exact expression is first derived for the outage probability, which involves performing a multiple-fold integration numerically. The computation complexity increases with the number of cochannel interferers in the system, making it difficult to compute for a large number of interferers. Two alternative expressions are proposed, which are significantly simpler to compute: a lower bound which involves computing only a single integral and an approximate expression based on the use of the central limit theorem that involves computing a two-fold integral. The accuracies of each of the exact, the lower bound and the approximate expressions are verified by comparing them with results obtained by means of Monte Carlo simulations. The proposed lower bound and approximate expressions prove to be accurate and simple tools for estimating the outage probability without having to revert to either the complicated exact expression or time-consuming simulations.