I really like this tool. It successfully presents a lot of complex information in a clear way, one you've got your head around the key or watched the video below. It has inspired me to think about how I present probabilistic information and I hope to see more innovation in this area in the not-too-distant future. It's a shame, however, that the skill is insufficient to offer forecasts for most of Europe and the North Sea where there is significant wind power capacity, though that is of course and issue with the forecast, not the visualisation.
Ukko is the result of a collaboration between the Barcelona Supercomputing Center and FutureEverthing using ECMWF seasonal forecasts, and well worth a play with!