In order to provide valuable and reliable numerical guidance include probabilistic forecast,state-of-the-art global ensemble forecast system has been implemented into National Centers for Environmental Prediction daily operation to service the general public.The forecast skills for various elements through statistical verification are offering the levels of confidence to general users when they apply these guidance.However,the skills are all differents rely on the forecast elements,spatial and temporal resolutions,and special events or the forecast extremes.As an example of large scale pattern prediction,the global ensemble forecast system (global ensemble mean) could provide about 10 days skillful forecast on average based on 60% Northern Hemisphere 500 hPa geopotential height anomaly correlation.The predictability or limit of prediction we will discuss in this article could be a good reference for model developers,stakeholders and general users in terms of their requirements from various forecast elements to the different spatial-temporal scales.Especially,the investigation of sources predictability are very important to advance our numerical system in terms of science and technowledge.When we understand the source of predictability,the scientists will know where to work on,and how to improve the system.To combine the traditional predictability study and recently developed global ensemble forecast system with full representation of uncertainty,the predictability and limit of prediction through state-of-art global ensemble forecast system could be another valuable reference.As a summary of predictability investigation,there could be about 15-,12-,10-days forecast skills for planetary wave,large scale and synoptic scale patterns respectively.For tropical prediction,a skill of Madden-Julian Oscillation could be extended to 32.5 days if we could reduce model bias and improve others.