Mapping past snow melt to understand future events

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While we do not know how much snow will melt this week, there is data on extreme snowmelt events over the past thirty years. By mapping the past, we might get a glance at the future. 

Rapid snowmelt can be dangerous, leading to localized flooding and effects downstream.

“Snowpack also has all the long distance impacts for different peak river basins, including the Mississippi,” said UArizona Climate Dynamics and Hydrometeorology Center Director Xubin Zeng, Ph.D. “I mean, at this time of the year, all for the next couple of months, the snow melts over and part of the country will affect reservoirs and rivers.”

In 2021, University of Arizona researchers mapped extreme snowmelt events over the last thirty years to better understand the processes behind rapid melting in a variety of regions.

“The mechanisms for extreme snow melt use are somewhat different for Minnesota versus for western U.S. You see, east of the Rocky Mountains, most of the time the snow melt is simply due to higher temperature,” explained Dr. Zeng. “Well, for western U.S., besides higher temperatures, sometimes the so-called rain and snow event would be very impactful in terms of causing substantial snow melts for the region east of Rocky Mountains. This could still happen if there is a very warm way that substantially accelerates the snow melt. That’s why the other thing is to look at the weather pattern for those events.”

This was the first study to characterize snowmelt across the U.S.

“We built into our own model for bringing all the measurements together, “ said Dr. Zeng. “Even for the same area, you can have very different snow depths and we take care of that and a key is to consider that history.”

One of the historical snowmelt events noted in the research paper was the Red River Flood of April 1997. In this case, an abnormally snowy few months in North Dakota and western Minnesota was followed by warmer temperatures with nights staying above freezing, resulting in flooding.