Snow-eater heat waves of the western United States
Alan M. Rhoades, Joshua Snowball North, William Rudisill, Benjamin J. Hatchett, Mark Risser, Areidy Beltran-Peña, Anne Heggli, Scott Hotaling, Laurie S. Huning, Andrew Joros, Matthew LaPlante, Ankur Mahesh, Adrienne M. Marshall, Rachel McCrary, Daniel McEvoy, Stefan Rahimi, Mark S. Raleigh, Calen Randall, Abhishekh Srivastava, Michael Wehner, Yang Zhou, Andrew D. JonesAbrupt snowmelt, triggered by rain-on-snow events or “snow-eater heat waves,” can cause flooding, initiate or accelerate snow drought, and affect water availability. However, the characteristics (e.g., area, duration, and frequency), impacts, and trends of snow-eater heat waves have received little attention. To address this gap, we developed a method to identify snow-eater heat waves and estimate their melt potential using 20th Century Reanalysis version 3 air temperature data, the TempestExtremes algorithm, and an operational snowmelt model (SNOW-17) across 1850–2015. Melt season snow-eater heat waves typically last 3 to 5 days, with three to five events, doubling snowmelt rates. Seven of 11 spring superfloods are shown to coincide with snow-eater heat waves. Since the 1850s, snow-eater heat waves have increased in area and frequency, decreased in duration, and shifted earlier in the melt season. Incorporating snow-eater heat-wave impacts into SNOW-17 enhances extreme melt estimates, improving water management support tools.