In Park City, Utah, skiers could find blades of grass poking through the slopes all winter long – a wonderful sign of a season that never came. Now, after one of the warmest winters on record, much of the West is entering spring with record low snowfall and the first heat wave that has pushed temperatures into the triple digits.
These problems can appear in a weather fiction book. But the winter in the West is not pleasant, the worst was frighteningly true. And, experts say, the troubling combination of low snow and sweltering temperatures could make the summer open for catastrophic weather. “There is no analog,” Marianne Cowherd, a climate scientist at Montana State University, said of the phenomenon. “There is no 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 is caused by what happens to the area’s snowpack, which is the basis of the existing water system. Snow makes up 60 to 70 percent of the Northwest’s water supply and is critical to the perennially thirsty Colorado River Basin, which supplies seven states. But most of the region had the warmest winter on record. That means a higher proportion of water has arrived as rain, and the snow that has fallen is melting faster than usual. Snowpack is very low, according to the federal Colorado River Basin Forecasting Center, which uses the federal Snow Telemetry network of monitoring stations going back half a century.
“Most of them have low or near low snowpack,” hydrologist Cody Moser said at the agency’s monthly briefing in early March. At the time, he said, the upper Colorado River, which covers water north of Lake Powell on the Colorado-Arizona border, had 40 percent of normal snowfall. That’s down to 25 to 30 percent.
Although winter rainfall is really average, how that water falls is important. Snow acts as a natural water storage system that spreads the water supply over weeks or months as it melts. This helps to preserve the rivers and reservoirs for a long time. In addition to snow, the humidity may be temporary. “Even if it rains, we don’t store it,” Cowherd said. “A lot of it ends up evaporating or running into the ocean, so it’s not in our reach.”
Cowherd will be watching the snow melt. On the other hand, warmer temperatures cause the snow to melt faster than usual. But the angle of the sun – the height of the sun – is lower than it would be in spring, which can hinder the melting process. “I’m very interested to see what the balance is,” he said, adding that the answer could be important to the water supply in the area. “We don’t have a reservoir of man-made reservoirs to store the amount of water we need.”
If the snow problems weren’t enough, a heat wave in mid-March also wreaked havoc in the West. The heat wave brought temperatures about 35 degrees above normal, according to research group Climate Central. More than 1,500 daily records were set in 11 locations. Several saw temperatures above 100 degrees Fahrenheit, and the US set a March national record of 112 in four cities.
An analysis carried out by the World Weather Attribution Initiative found that this warming would be “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. He added that extreme temperatures at the beginning of the year “tend to be dangerous for people because your body is not used to it yet.”
Although the heat broke out in many places after about a week, the effects may last into the summer. July-like temperatures and dwindling snowpack threaten the West’s water supply. A forecast by the US Bureau of Reclamation indicates that levels in Lake Powell could drop below the minimum required to generate power in early August, and possibly in December. Some Colorado residents are already facing the first water use restrictions ever seen.
“This winter was unusually warm and didn’t provide the snow we needed,” Alan Salazar, CEO of Denver Water, the state’s largest water provider, said in a statement last week. The utility declared a Stage 1 emergency, which called for a 20 percent reduction in use and mandatory restrictions on outdoor irrigation. “This drought is yet another reminder of the effects of climate change on our water supply,” he said.
Such conditions increase the risk of wildfires. Excessive runoff and high temperatures promote the early growth of flammable vegetation, and unusually warm weather turns all greenery into fire. “The heat recorded over the past few weeks has put us in the ‘green’ of the year,” August Isernhagen, division commander for the Truckee Meadows Fire Protection District, told the University of Nevada, Reno. “This, along with many other human impacts on the environment, has created unpredictable conditions during this fire season.”
If these dangerous conditions occur, the consequences can be dire. Shortage of water supply can disrupt agricultural production that feeds people across the country. Wildfires can endanger lives, displace thousands, and cause billions of dollars in damage. However, a lot can change in the next few months.
Barnes said early temperatures don’t necessarily mean there will be more later in the year. The weather between heat events is also important, and can go in many ways. An upcoming El Nino weather pattern, for example, could help reduce potential droughts. The snowpack problem may even return.
“We could have a big snowstorm tomorrow and it’s going to be fun,” Cowherd said. But based on the current weather forecast, he warned, “I don’t think this is likely to happen.”
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