I dont understand the point about Ensembles. Without seeming to wade in half way through. The fact forecasting accuracy is low, has nothing to do with any single tool used to forecast weather. (To which Ensembles are but one element of an array of "tools" available) The difficulty in forecasting is to do with a numerous string of factors, related to our geographical location. An nothing to do with what tools are used, or how individaully they rate as forecasting tools for the mid term.