This report explores the quantification of uncertainty in the NEWA project. Uncertainty is un- derstood here as the result of the contributions of model sensitivity to different model setups, and of model errors in a model-data comparison framework. The first part (Sec 3 of this report ex- plores the uncertainty derived from model sensitivity subjected to the decisions taken regarding the use of different models setups and how these produce variability in model output. The range of this variability has been regarded as spread in model output and has been quantified in various manners. The second part of this report (Sec. 4 addresses how model performance can be char- acterised with the data at hand and whether decisions regarding selection of a given model setup for a production run can be taken on the basis of model performance in a variety of situations, using different variables and datasets as observational targets: wind farm data from Vestas; tall masts and wind profiles; surface wind data; satellite data and reanalysis outputs.