The first week of the new year is expected to bring a bounty of storms that will bolster the state’s snowpack, a vast and vital frozen reservoir that, as 2019 came to a close, was at about half its normal year-end depth.
An initial front, on the warm side, barreled from the Pacific just in advance of 2020, carrying gusting lowland winds and Tuesday rain to Snoqualmie Pass. The wave of storms is likely to continue through the weekend and include chillier temperatures that will bring more mid- and lower-elevation snow, which — as it melts in the spring and summer — provides water that supports fish, farm irrigation and power generation.
If winter includes a lot more moist, cool weather, the late-season snowpack of April still could reach more than 80% of the long-term average — enough to prevent serious water shortages.
“This is our third-slowest start to the winter (snowpack) since 1990,” said Scott Pattee, a water-supply specialist with the Natural Resources Conservation Service. “The odds of us catching up completely are pretty slim.”
Washington’s snowpack is measured through more than 70 conservation service survey sites, which track the water content compared with a 4o-year, point-in-time average. As of Tuesday, those sites showed the snowpack ranged from 29% of normal in the Lower Columbia basin of Southwest Washington to a high of 65% in the Upper Columbia basin of North Central Washington, bordering Canada. Across the state, the snowpack averaged 45%, according to Pattee.
The subpar snowpack is due largely to a very dry November and a warmer-than-normal December that resulted in more moisture landing as rain in much of the state’s mountain range.
In the Seattle area, December rainfall at the end of Monday totaled 7.7 inches, well above the monthly average of 5.03 inches, according to the National Weather Service. But temperatures averaged 3.6 degrees warmer than normal, and even the big pre-Christmas storm eventually turned from snow to rain at Snoqualmie Pass.
Four ski areas are located at Snoqualmie Pass, but only two were open during the peak Christmas week. In the days ahead, conditions are expected to improve there as well as at other Washington ski areas.
“We definitely need one of those typical Northwest storm cycles that dumps 5 feet in a week,” said Karter Riach, director of marketing at The Summit at Snoqualmie. “I’m hopeful we can get the next big storm soon and get everyone excited.”
Winter storms welcome
National Weather Service and Northwest Avalanche Service forecasters say the early January storms will include some warmer Pacific air that produces rain at lower mountain elevations, with Tuesday night snow levels expect to rise to as high as 6,500 feet in the Cascades. But storms expected later in the week will have enough cool air to produce snow from 1,500 to 5,000 feet, where deficits have been the greatest, and include more than a half-foot at Snoqualmie Pass.
“This won’t completely change the landscape. But I think we will be in a better place,” said Dennis D’Amico, forecast director of the Northwest Avalanche Center
And Cliff Mass, a University of Washington professor of atmospheric sciences, says weather models make him upbeat about the next few months.
“My general caution … is not to expect we will have water problems next summer based on what has happened so far … we need to see how the rest of the winter plays out,” Mass said.
Big winter storms would be welcome by federal Bureau of Reclamation officials who monitor Yakima basin reservoirs that provide critical irrigation flows for fruit orchards and farms growing vegetables, hops and other crops.
These reservoirs are drawn way down by summer’s end. They get an early recharge from fall rains, then gain a lot more water as the snow pack melts in the spring.
In 2019, there wasn’t much rain in November, which ranked as the fourth-driest in the 105 years of record-keeping in Yakima Basin, according to bureau statistics. The basin snowpack also is lagging at far below average. All of this increases the risk of summer water shortages, which Chuck Garner, a Reclamation Bureau operations supervisor, puts at 35% to 40%.
“It’s too early to make any real projections,” Garner said. “We’ve been bouncing around, going from really good months to really bad months. I’ve been in the basin for 27 years, and it’s not really scaring me … but the patterns are changing.”
Climate scientists say the snowpack in any one year is considered to be a reflection of weather. But they also note that a long-term warming trend is underway due to the buildup of greenhouse gases in the atmosphere.
They have developed models for the future, based on different levels of fossil-fuel combustion that releases greenhouse gases. They forecast warmer winter temperatures will produce more frequent winter rain on mountain slopes, and thus contribute to a long-term decline of the average mountain snowpack.
One forecast from UW’s Climate Impacts Group estimates that by midcentury, the average state snowpack could shrink by nearly 40%. Other studies predict that will be accompanied by a shift to an earlier spring snow melt, which leaves less cool water flowing into streams during the hotter summer months.
Nick Bond, Washington state’s climatologist, said there will still be plenty of changes from year to year. But in Washington state much of the snow storage is on relatively low-elevation slopes, from 3,000 to 5,000 feet, that are more vulnerable to small increases in temperatures.
“Subtle long-term shifts that raise the (average) freezing levels can have a big impact in how much water you have in the snowpack,” Bond said.