Monitoring the daily evolution and extent of snow drought

Abstract. Snow droughts are commonly defined as below-average snowpack at a point in time, typically 1 April the western United States (wUS). This definition is valuable for interpreting state of but obscures temporal evolution snow drought. Borrowing from dynamical systems theory, we applied phase diagrams to visually examine daily water equivalent (SWE) and accumulated precipitation conditions maritime, intermountain, continental climates wUS using station observations well spatially distributed estimates SWE precipitation. Using percentile-based drought definition, highlighted decision-relevant aspects such onset, evolution, termination. The diagram approach can be used tandem with reveal variability type extent. When combined streamflow or other environmental data, spatial help inform monitoring early warning link impacts on ecosystems, resources, recreation. A web tool introduced allowing users create real-time historic diagrams.