The West’s unprecedented winter could fuel a summer of disaster

In Park City, Utah, skiers could find patches of grass poking through the slopes for much of the winter — a striking sign of a season that never really arrived. Now, after one of the warmest winters on record, much of the West is entering spring with snowpack at historic lows and an early heat wave that pushed temperatures into triple digits.

These woes could be straight out of a climate fiction novel. But the West’s no good, very bad winter was alarmingly real. And, experts say, a worrisome combination of low snowpack and a devastating heatwave could create a summer ripe for climate disasters. “There is no analog,” Marianne Cowherd, a climate scientist at Montana State University, said of what’s happening. “There isn’t a year in the historical record we can look to for information … This limits our ability to look to the past for insight.”

Much of that uncertainty stems from what’s happening to the region’s snowpack, a cornerstone of its water system. Snow accounts for 60 to 70 percent of the Northwest’s water supply and is especially critical to the ever-thirsty Colorado River Basin, which supplies seven states. But much of the region has experienced the warmest winter on record. That has meant a higher proportion of water arrived as rain, and the snow that did fall melted more quickly than usual. Snowpack is critically low, according to the federal Colorado River Basin Forecasting Center, which utilizes the federal government’s Snow Telemetry network of monitoring stations that go back half a century.

“The majority of them have record low or near record low snowpack conditions,” said hydrologist Cody Moser 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, have about 40 percent of normal snow cover. That has since dropped to 25 to 30 percent. 

While winter precipitation has actually been fairly average, how that water falls is important, too. Snow acts as a natural water-storage mechanism that spreads the delivery of water out over weeks or even months as it melts. This helps keep rivers and reservoirs flush for longer. Without snow, the moisture can be fleeting. “Even when we’re getting precipitation we’re not storing it,” Cowherd said. “A lot of it actually just 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 watching the snowmelt closely. On one hand, the warmer temperatures are priming the snow to liquify more quickly than normal. But the solar angle — the sun’s maximum height — is lower now than it would be later in the spring, which could impede the melting trend. “I’m really interested to see how those balance,” she said, adding that the answer could be critical to the region’s water supply. “We don’t have the reservoir capacity behind human-built dams to hold the amount of water that we need.”

If snowpack problems weren’t enough, a mid-March heatwave also wreaked havoc in the West. A heat dome brought temperatures as much as 35 degrees above normal, according to the research group Climate Central. More than 1,500 daily records were set across 11 states. Several saw temperatures above 100 degrees Fahrenheit, and the U.S set a national March 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 Imperial College London’s Centre for Environmental Policy who was part of the team behind the report. She added that extreme temperatures this early in the year “tend to be more dangerous for people because your body is not yet acclimatized.” 

While the heat broke in many places after about a week, the impacts could last through the summer. July-like temperatures and dwindling snowpack jeopardize the West’s fragile water supply. The U.S. Bureau of Reclamation’s forecast shows that levels in Lake Powell could dip below the minimum needed to generate power as early as August, and most probably by December. Some Colorado residents are already facing the earliest restrictions on water use ever seen.

“This winter was unusually warm and did not deliver 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 a Stage 1 emergency, which called for a 20 percent cut in usage and mandatory restrictions on outdoor watering. “This drought is also a reminder of the impacts of climate change on our water supply,” he said. 

Such conditions heighten the risk of wildfires. Excessive runoff and high heat foster early growth of vegetation that can fuel them, and unseasonably warm weather turns all that greenery to kindling. “Record heat over the previous weeks has put us into early ‘green up’ for the year,” August Isernhagen, a division chief in the Truckee Meadows Fire Protection District, told the University of Nevada, Reno. “This, coupled with many other human impacts on the landscape, has created potential for unprecedented conditions this fire season.”

If these risk trajectories pan out, the impacts could be catastrophic. Low water supplies could upend agricultural operations that feed people across the country. Wildfires could threaten lives, displace thousands, and cause billions of dollars in damage. Still, a lot could change over the next few months.

Barnes said an early heatwave doesn’t necessarily mean there will be more of them later in the year. The weather between heat events also matters, and could go in many directions. A looming El Nino climate pattern could, for example, help alleviate a potential drought. The snowpack problem could even rebound, too.

“We could have a huge snow storm tomorrow and it would be great,” Cowherd said. But based on the current weather forecasts, she cautioned, “I don’t think this is likely to happen.”