Snowpack observations in the Intermountain West are sparse and short, making them
difficult for use in depicting past variability and extremes. This study presents a reconstruction
of April 1 snow water equivalent (SWE) for the period of 1850–1989 using increment cores
collected by the U.S. Forest Service, Interior West Forest Inventory and Analysis program (FIA).
In the state of Utah, SWE was reconstructed for 38 snow course locations using a combination of
standardized tree-ring indices derived from both FIA increment cores and publicly available tree-ring
chronologies. These individual reconstructions were then interpolated to a 4-km grid using an
objective analysis with elevation correction to create an SWE product. The results showed a significant
correlation with observed SWE as well as good correspondence to regional tree-ring-based drought
reconstructions. Diagnostic analysis showed statewide coherent climate variability on inter-annual
and inter-decadal time-scales, with added geographical details that would not be possible using
courser pre-instrumental proxy datasets. This SWE reconstruction provides water resource managers
and forecasters with better spatial resolution to examine past variability in snowpack, which will be
important as future hydroclimatic variability is amplified by climate change.
