Characterizing Snow Drought Conditions across the United States

In many regions of the world, drought is not uncommon and it can be manifested as low snow water equivalent (SWE) accumulation or storage. Since large populations derive their water resources from snow, years of below average SWE and shifts in the SWE distribution (spatial and temporal) can stress available water resources. As a result, snow drought has emerged as a key area requiring additional study since it is less often characterized than many other types of drought. Snow drought can result from below average precipitation or warm temperatures that shift the partitioning of precipitation from snowfall to rainfall and/or promote ablation, leading to below average SWE. Using spatially-distributed historical SWE information, we characterize SWE variability to understand changes in its spatiotemporal distribution and the relationship between SWE and hydrometeorological variables (e.g., temperature, humidity, precipitation, etc.) across the Conterminous United States (CONUS). The extent to which these relationships show regional or physiographic (e.g., elevational) signatures is also examined. We explore metrics for identifying and quantifying snow drought characteristics (e.g., severity, duration, onset, termination, etc.) as they vary in space and time across a variety of topographic, climatic, and ecologic regimes.