Above Normal, but Not Out of the Woods: Precipitation Chips Away at California Drought, but the Water Deficit RemainsWritten by Paige Blankenbuehler
At the beginning of February last year, South Lake Tahoe in California was nearly 60 degrees Fahrenheit—almost 20 degrees above its historic average.
At that time, the drought had been dragging along for four years, and chair lifts at nearby ski resorts were swaying over barren slopes. Representatives from the California Department of Water Resources called the Sierra Nevada snowpack “dismally meager,” at only 23 percent of normal.
This year, it’s a drastically different story. January has been California’s best month for the snowpack since 2011, and the state’s measurements are at 127 percent of normal. Still, it’s still not enough to make up the deficit from the persisting drought in the state. It is enough, though, to keep ski resorts running and reservoirs in the state from drying up.
Above-normal snowpack measurements are tracking for most of the West, too. (See the chart below.) The season was off to a slow start with sporadic storms from October through December, but January winter precipitation increased measurements across all states, according to the Natural Resources Conservation Service’s SNOTEL sites, which measure snow depth at thousands of stations nation-wide. Over the past month, California snowpack increased from 90 to 127 percent, and Arizona jumped from 83 percent to 113 percent of normal.
Only two Western states, Montana and Wyoming, are below the historic benchmark for “normal” at this time of year—and not by much. North-central Wyoming and the eastern slope of the Northern Rockies in Montana are the low-snow areas. Both states are at more than 80 percent of normal for this time of year, and February is a crucial month for snow. Snowpack typically builds until April, says Alan Haynes, a hydrologist for the California Nevada River Forecast Center. But even in states with snowpack measurements lagging behind, readings from early in the season have improved.Since December, snow depth in Montana has hobbled to 84 percent of normal —from 73 percent in early December. And Wyoming similarly increased to 84 percent, from about 75.
Measurements from SNOTEL sites across the West, which have been recording precipitation and snow depth this season since Oct. 1, 2015, are painting a reverse picture of last year. Areas that were far below average last year—the Tahoe Basin in California and the Cascades in the Pacific Northwest—are recording the highest precipitation in the West so far this season.
In California, local forecasters say the past few months of snow are finally chipping away at the state’s five-year drought. The deficit will be hard to overcome, Haynes says, but if this season continues, the state might avoid fallowing fields. California gets 30 percent of its total water supply from snowpack, and reservoirs that have been low are now slowly filling up. Shasta Reservoir, one of the largest storage systems in the state, is currently more than 50 percent full, or about 75 percent of the historical average for this time.
However, a late-winter dry spell could cause further problems.
“If we get shut out for the rest of the winter, the outlook could be bleak,” Haynes says.
Winter recreation in California is also benefiting from the abundant snow. The Hagens Meadow SNOTEL site near South Lake Tahoe is reporting 53 inches of snow depth, or 158 percent of normal, and the Ostrander Lake site, in south Yosemite National Park, has had 220 inches of snow.
Although the surplus of snow in the West is a positive sign for drought-stricken areas, it has been a dangerous season for those in the backcountry. Fifteen people have died in avalanches this season, and 12 of those deaths occurred in January alone. Ten of those fatalities, astoundingly, occurred in just an eight-day period spanning six Western states: Washington, Wyoming, Colorado, Montana, Utah and Alaska. January was the third-deadliest month recorded since 2001, according to Karl Birkeland, director of the National Avalanche Center.
Sporadic storms from October through December created a weak foundation in snowpack across the region. The clear spells between storms allowed “depth hoar,” a sugary and large-grained snow, to develop, and large storms in December and January added dense layers on top of the fragile base.
“That set the stage of the cluster of avalanche deaths in January,” Birkeland says.
While El Niño may be creating a more robust winter storm pattern, it’s difficult to attribute all of the heavy snow to the global weather phenomenon.
“This year has been a really strong El Niño, but we’re seeing snowfall patterns that are somewhat unusual for this weather event,” Haynes says. The Northwest, which would typically be fairly dry, is wet. However, precipitation in south-central California hasn’t lived up to early El Niño predictions for that part of the state.
Still, the U.S. Drought Monitor remains cautiously optimistic about recovery. According to the center’s Jan. 28 report, “the trend is going in the right direction for now with a good chunk of the snow season still left to play out over the next two months.”
Paige Blankenbuehler is an editorial fellow at High Country News, where this story first appeared.