High Risk of Unprecedented U.K. Rainfall

In winter 2013/14 a succession of storms hit the UK leading to record rainfall and flooding in many regions including south east England. There was no observational precedent for this level of rainfall. We use the UNSEEN method (UNprecedented Simulated Extremes in ENsembles) to calculate the risk of such events. We analyse a large ensemble of high-resolution initialised climate simulations to show that this event could have been anticipated, and that in the current climate there remains a high chance of exceeding the observed record monthly rainfall totals in many regions of the UK. In south east England there is a 7% chance of exceeding the current rainfall record in at least one month in any given winter. Expanding our analysis to some other regions of England and Wales the risk increases to a 34% chance of breaking a regional record somewhere each winter. As we are using a dynamical global model we are able to assess the atmospheric conditions surrounding the modelled extreme events to provide further insight into the dynamics of the events. This method could be applied to other climatic indicators in different regions globally to assess the risk of extremes in the current climate.