Scientists developed a new method to better identify and understand the particular heat waves that cause abrupt snowmelt.
By Carly Nairn, Courthouse News Service
With climate change, wildfires and heat waves, an abundant snowpack becomes a more precious resource every year.
Increased temperatures earlier in the year followed by other weather-related phenomena are causing much of the western United States to experience what scientists are calling “snow-eater” heat waves.
A new study, published Wednesday in the journal Science Advances, analyzes the weather events using a method developed to identify the heat waves. Snow-eater heat waves are pretty much like they sound — abrupt snowmelt triggered by rain-on-snow and followed by several days of unseasonably high temperatures.
But some of the “snow-eater” heat wave characteristics and impacts haven’t been broadly studied before the paper, the scientists said.
Analyzing air temperature data from 1850 to 2015 and incorporating a snowmelt model, the scientists were able to estimate heat waves and their melt potential.
“Melt season snow-eater heat waves typically last three to five days, with three to five events per decade, doubling snowmelt rates,” said the scientists, including Lawrence Berkeley National Laboratory researcher and lead author Alan Rhoades, in the study.
“Seven of 11 spring super floods are shown to coincide with snow-eater heat waves. Since the 1850’s, snow-eater heat waves have increased in area and frequency, decreased in duration, and shifted earlier in the melt season,” the scientists said.
The authors noted that in the spring and early summer in the West, heat waves occur regularly. But they have nearly doubled in frequency and intensity since the mid-1990’s. And with those extreme temperatures comes increased snowmelt, which in turn can cause severe floods.
Snow-eater heat waves are caused by a buildup of abnormally high pressure that diverts storms, acting like “a boulder in a stream,” said Rhoades in an email to Courthouse News.
“The anomalous buildup of high pressure leads to warmer and drier conditions that can lead to sustained above-freezing conditions throughout the day and night. When these conditions persist for several days, snowpack melts twice as fast, on average, as is typically expected,” he said.
Rhoades said snow-eater heat waves have occurred often over the last few centuries, but a particularly impactful one just happened in March 2026. In the Intermountain West — a region that primarily includes Nevada, Idaho and Utah — drought conditions persisted for the most of the winter and then a snow-eater heat wave occurred and rapidly depleted the small amount of mountain snowpack left.
“This resulted in the second lowest inflows on record to Lake Powell, our nation’s largest reservoir, at a time when Colorado River water managers were hoping for a miracle March to alleviate stress on the Colorado River compact negotiations,” he said.
To analyze other effects of snow-eater heat waves, a 1983 Utah “super flood” was used as a case study in the new report to explore the effects of the unseasonal melting events. The researchers believe the method they developed can assist municipal water management tools in the future with forecasting and to better understand the impacts of how agriculture and urban areas use water during drier seasons.
“The ability to predict the area, duration, frequency, and intensity of snow-eater heatwave events at sub-seasonal to seasonal timescales could also be worth exploring in future work,” the scientists said.
“Given the identified size and potential impact on water resources and natural hazards, additional work on snow-eater heat-wave events is needed.”
