The West’s unprecedented winter could fuel a summer of disaster
In Park City, Utah, skiers could find patches of grass on the slopes for much of the winter — a stark sign of a season that never really arrived. Now, after one of the warmest winters on record, much of the West is heading into spring with a historically low snowpack and an early heat wave that has pushed temperatures into triple digits.
These misfortunes could come straight out of a climate fiction novel. But the very bad winter in the West was alarmingly real. And, experts say, a worrying combination of low snowpack and a devastating heatwave could create a summer ripe for climate disasters. “There’s no analogue,” Marianne Cowherd, a climatologist at Montana State University, said of what’s happening. “There is not one year in the historical record that we can look to for information… This limits our ability to look to the past for insight.” »
Much of that uncertainty comes from what happens to the region’s snowpack, the cornerstone of its water system. Snow accounts for 60 to 70 percent of the Northwest’s water supply and is especially critical for the perennially thirsty Colorado River Basin, which supplies water to seven states. But much of the region experienced the warmest winter on record. This means that a higher proportion of water arrived as rain and the snow that fell melted more quickly than usual. The snowpack is extremely low, according to the federal Colorado River Basin Forecast Center, which uses the federal government’s network of snow telemetry monitoring stations that dates back half a century.
“The majority of them have record or near record snow conditions,” hydrologist Cody Moser said at the center’s monthly briefing in early March. At that time, he said the upper Colorado River basin, which covers the watershed north of Lake Powell on the Colorado-Arizona border, had about 40 percent of normal snow cover. Since then, this figure has fallen to 25 or 30 percent.
Although winter precipitation has been fairly average, the manner in which the water falls is also important. Snow acts as a natural water storage mechanism that spreads water distribution over weeks or even months as it melts. This helps keep rivers and reservoirs empty for longer. Without snow, humidity can be temporary. “Even when we get precipitation, we don’t store it,” Cowherd said. “A lot of it ends up evaporating or flowing out to the ocean, so it’s not necessarily in a place where we can still access it.”
Cowherd will be closely monitoring the snowmelt. On the one hand, warmer temperatures cause snow to liquefy more quickly than normal. But the solar angle – the maximum height of the sun – is lower now than it would be later in the spring, which could hinder the melting trend. “I’m really interested to see how these factors balance out,” she said, adding that the answer could be crucial to the region’s water supply. “We don’t have the reservoir capacity behind man-made dams to hold the amount of water we need.”
As if snowpack problems weren’t enough, a mid-March heat wave also wreaked havoc in the West. A heat dome brought temperatures up to 35 degrees above normal, according to the research group Climate Central. More than 1,500 daily records were set in 11 states. Several saw temperatures above 100 degrees Fahrenheit, and the United States set a March national record of 112 in four cities.
An analysis by the World Weather Attribution Initiative found that this heatwave would have been “virtually impossible” without climate change. “The role of climate change is clear,” said Clair Barnes, a researcher at the Center for Environmental Policy at Imperial College London, who was part of the team behind the report. She added that extreme temperatures early in the year “tend to be more dangerous for people because their bodies are not yet acclimated.”
Although the heat subsided in many places after about a week, the impacts could last through the summer. July temperatures and diminishing snowpack are putting the West’s fragile water supply at risk. Forecasts from the U.S. Bureau of Reclamation show that Lake Powell levels could drop below the minimum needed to generate electricity as early as August, and most likely by December. Some Colorado residents are already facing the first water use restrictions ever.
“This winter has been unusually warm and has not provided the snow we need,” Alan Salazar, CEO of Denver Water, the state’s largest water provider, said in a statement last week. The utility declared a Level 1 emergency, which called for a 20 percent reduction in usage and mandatory restrictions on outdoor watering. “This drought also reminds us of the impacts of climate change on our water supply,” he said.
Such conditions increase the risk of wildfires. Excessive runoff and high heat promote early growth of vegetation that can feed them, and unusually warm weather turns all that greenery into kindling. “The record heat of the previous weeks allowed us to go green early for the year,” said August Isernhagen, division chief of the Truckee Meadows Fire Protection District at the University of Nevada, Reno. “This, coupled with many other human impacts on the landscape, has created the potential for unprecedented conditions during this fire season. »
If these risk trajectories materialize, the impacts could be catastrophic. Low water supplies could disrupt agricultural operations that feed people across the country. Wildfires could threaten lives, displace thousands and cause billions of dollars in damage. However, a lot could change in the coming months.
Barnes said an early heat wave doesn’t necessarily mean there will be more later in the year. The weather between heat events is also important and could go in many directions. The threat of an El Nino climatic phenomenon could, for example, help to alleviate a possible drought. The snow cover problem could even rebound.
“We could have a huge snowstorm tomorrow and that would be great,” Cowherd said. But based on current weather forecasts, she warned: “I don’t think that’s likely to happen.”
