Edinburgh at last began to applysomepressure of their own and, after Wallace was sent to the sin-bin for an infringement, Paterson kicked the resulting penalty to narrow the gap to three points.
Wenger's side finally managed to applysomepressure, but found Chelsea's defence in resilient mood as Cole made a superb saving tackle as Samir Nasri shaped to shoot and Cech saved well from Fabregas' low free-kick.
Edinburgh, who were without several second-row regulars, continued to apply the pressure and it paid off when Cairns raced through following some excellent handling and offloading.
Professional forecasters often applysome version of a Markov model in order to get a baseline and then incorporate other factors, such as barometric pressure, to improve accuracy.