Atmospheric water vapor plays an enormously important role in the energy budget of the planet’s high latitudes., Its distribution is intimately tied to atmosphere, ocean and cryosphere circulation features and it is strongly affected by processes that serve as sources and sinks to/from other components of the Earth System. Water vapor also participates in many important feedback mechanisms influencing the planet’s climate and response to forcing agents. This presentation will survey the range of CMIP6 model variation in high-latitude simulations of water vapor, the transport/source/sink processes that control the water vapor distribution, and the implications for the feedbacks that are important to climate and climate change, and as a source of water to the ocean and cryosphere. Most of the focus will be on simulations of the recent past (AMIP) to facilitate comparison with observations and reanalysis products. We are particularly interested in the episodic filamentary structures (atmospheric rivers) that can play an important role as a delivery agent of water to high latitudes and plan to contrast the range of behavior seen in model simulations with best estimates of that transport from observational estimates.