Role of extreme snowfall events in interannual variability of snowfall accumulation in the western United States

Abstract

Water resources in the western United States are contingent on interannual variations in snowpack. Interannual snowpack variability has been attributed to large-scale climate patterns including the El Niño-Southern Oscillation (ENSO), however, the contribution of snowfall frequency and extreme snowfall events to this variability are less well quantified. Long-term records from Snowpack Telemetry and Cooperative Observer Program stations in the 11 western states were used to investigate these relationships by considering the number of snowfall days and snowfall water equivalent (SFE) of extreme snowfall events. The top decile of snowfall events contributed 20-38% of annual SFE, depending on the region. An average of 65% and 69% of the interannual variability in annual SFE was explained by snowfall days and SFE of top decile snowfall events, respectively, with extreme events being a more significant predictor at most stations. The latitudinal dipole in SFE during ENSO phases results from changes in snowfall frequency and extreme events. In the Pacific Northwest, above normal SFE during La Niña winters was a product of both larger contributions from extremes and more snowfall days, while below normal SFE during El Niño winters was primarily associated with a substantial reduction in extremes. Conversely, annual SFE during ENSO phases in the mountains of Arizona was more closely linked to fluctuations in snowfall days than extremes. Results indicate the importance of extreme snowfall events in shaping interannual variability in water resources and suggest that improved predictive ability may inform better water resource management now and in the coming decades.

Does Including Soil Moisture Observations Improve Operational Streamflow Forecasts in Snow‐Dominated Watersheds?

“…Soil moisture offers an additional source of information that could account for shifts from snowpack stores to subsurface stores. In addition, capturing extreme precipitation events that are outside of historical ranges is likely to become increasingly important in the future (Lute and Abatzoglou, ; O'Gorman, ). The accuracy improvement in watersheds where 2011 was the wettest year on record (Figure ) bodes well for the potential of soil moisture to help address extreme climate years.…”

Regionalization of snowfall frequency and trends over the contiguous United States

“…During a winter with positive Nino 3.4 SST anomalies there is a southward shift in the jet stream, resulting in a decrease in snowfall frequency in the Pacific Northwest (McCabe and Dettinger, 2002;Lute and Abatzoglou, 2014). This region also has a negative correlation with Northern Hemispheric annual temperature indicating that precipitation is likely falling more frequently in liquid rather than solid form during warm years.…”

Responses of runoff to historical and future climate variability over China

“…Also note that some other natural water sources, such as snow and glaciers, which may contribute to R, are overlooked in this study. Lute and Abatzoglou (2014) highlighted the importance of extreme snowfall events in shaping the interannual variability of the water balance. The melting of snow and glaciers is generally significant at a seasonal timescale in some high-altitude regions of China.…”