Western North America (WNA) climate variations and changes can have substantial socio-economic impacts within and beyond the WNA region.  Some of the most pronounced variations and changes are associated with large scale anomalous atmospheric ridging or troughing over or near WNA that occurring at subseasonal to decadal scales.  These anomalies and their direct impacts can extend from the Alaska to Mexico, and from the northeast Pacific to eastern North America, and include, for example, anomalies in surface temperature, atmospheric river activity, precipitation, snow and ice melting, soil moisture, and ocean circulation.  These environmental anomalies in turn lead to impacts on, for example, the management of water resources, droughts, floods, wildfires, electric power generation, and fisheries.  The overall objectives of this session are to help develop a more comprehensive and integrated understanding of WNA climate variations and changes (especially the role of ridging / troughing events), promote collaborative efforts, and improve prediction and decision support.  We invite researchers, operational analysts and forecasters, decision support providers, and others to share their progress in identifying and predicting subseasonal to decadal WNA climate variations and changes.  We especially encourage presentations on WNA ridging and troughing events, and related anomalies and impacts.  These include, for example, investigations of: ridiculously resilient ridging; northeast Pacific sea surface temperature blobs; climate scale variations and changes in atmospheric rivers, Santa Ana events, wildfires, and coastal upwelling; and decision support for resource and emergency managers.  We welcome presentations from observational, theoretical, modeling, forecasting, and applied perspectives, such as studies of: links to El Nino – La Nina, Indian Ocean Dipole, Madden-Julian Oscillation, Arctic Oscillation, and climate change; low frequency wave dynamics, climate-weather interactions, hindcast and forecast skill assessments, multi-decadal projections, and applications of climate information in planning and management.