Do you ever wonder where the winter forecasts for the United States come from and how they determine what the likely conditions are going to be? The Europeans do similar forecasts for their own winter, and this long and detailed article from Severe Weather Europe provides a lot of information into how the forecasts are made based on ENSO status, global climate models, and stratospheric models. The article may be a bit too jargony for some people but there is a lot of good information about the impacts of different parts of the weather system, including how La Nina influences worldwide weather, how Sudden Stratospheric Warmings (SSW) can affect conditions here in the United States, and how all of this different information is combined to create a winter forecast.