Snowpack rebounds emphatically after dismal start
A dismal start for Colorado’s snowpack season is starting to feel like a distant memory after numerous storms that have boosted the statewide total to 150 percent of median as of Tuesday.
Snowpack accumulation, so crucial to agricultural and municipal water supplies, had been off to its worst start in more than 32 years in Colorado, at 6 percent of normal as of Nov. 17, the Natural Resources Conservation Service says.
“At that point prospects for reaching normal snowpack conditions by January 1st, 2017, were bleak, and chances of achieving normal snowpack by late April, when snowpack typically peaks, looked doubtful,” Brian Domonkos, NRCS snow survey supervisor in Colorado, said in a news release.
But a series of storms arrived starting on Nov. 17, resulting in a statewide gain of 7.4 inches of snow water equivalent through the end of the year, the fastest rate of gain over that time period since 1986.
The gains have continued since then thanks to storms like the ones that have wreaked havoc on western Colorado roadways in recent days. The state’s current snowpack of 150 percent of median is up from 114 percent at the month’s start. It rose 14 percentage points just between Monday and Tuesday.
Snowpack in Colorado’s Upper Colorado River Basin was at 146 percent of median Tuesday, with the Gunnison River Basin at 158 percent of median. The state’s southwest corner — the San Miguel, Dolores, Animas and San Juan river basins — led the state, at 161 percent. And even the region with the lowest snowpack, the Yampa and White river basins, is at 133 percent.
Precipitation in December in the Colorado River Basin was 181 percent of average, the NRCS says. Precipitation in the Gunnison Basin and far southwest Colorado were 170 and 171 percent of average for the month, respectively.
A high-pressure ridge had been blocking storms from reaching Colorado early in the snowpack season.
“We weren’t getting into the storm track so well,” said Aldis Strautins, a hydrologist for the National Weather Service in Grand Junction. “Now we’re into the storm track of late.”
Reservoir storage as of Jan. 1 was at 105 percent of average statewide, 106 percent of average in the Colorado Basin and 103 percent in the Gunnison Basin.
“Given current reservoir capacity, the collective storage in the majority of Colorado’s river basins will be well poised to provide adequate water supply if the above normal precipitation and snowpack trends experienced during December do not continue for the remainder of the water year,” the NRCS said in a start-of-the-year water supply outlook for Colorado.
Strautins said streamflows in Colorado this year are currently predicted to be normal or slightly below normal, but it’s early in the season to be trying to make such projections. Last fall’s soil moisture had been lower than normal going into winter.
Weather in the West currently remains under the influence of a weak La Niña pattern. La Niñas are associated with lower-than-normal surface ocean temperatures in the equatorial Pacific Ocean, and in Colorado tend to produce more snowfall in northern Colorado than southern Colorado.
“Those are kind of the trends. They don’t always work out that way,” Strautins said, pointing to state-leading snowfall so far this year in southern Colorado basins.
The recent string of storms have dumped so much heavy, wet snow that they’ve triggered avalanches — or fears of sliding snow — that have closed several high mountain passes in recent days.
Colorado Highway 65 over Grand Mesa reopened late Tuesday after being closed Monday for avalanche mitigation, according to Colorado Department of Transportation officials. Avalanche crews released two planned slides on the mesa Tuesday morning that were between 4 and 6 feet deep in some sections.
Planned avalanches were slated for several areas across the state as massive wet snowfalls created hazardous conditions in the backcountry as well as near major thoroughfares, evidenced by Tuesday morning’s natural avalanche that buried westbound lanes of Interstate 70 near Vail Pass with up to 15 feet of snow.
Ethan Greene, director of the Colorado Avalanche Information Center, said the snows throughout Colorado are wetter than normal.
“This is a really unusual event and it has to do with the amount of snow and the water content of that snow,” Greene said. “Some of the water contents are really impressive.”
CDOT Director of Highway Maintenance Kyle Lester said nearly every pass in the state system has had some natural slides from the weight of the wet snow.
“This is an extraordinary event,” Lester said. “We see these patches periodically throughout the year where every crew in the state is working avalanches during that storm cycle. The unique part about this is the moisture.”
While crews are working to clean up avalanches that crossed roads, as in Vail, Lester said new heavy snow in the backcountry just needs time to settle and stabilize.
Forecasters expect to see a transition to a more neutral phase between a La Niña and an El Niño early this year. El Niños are tied to warmer equatorial Pacific Ocean temperatures and generally favor southern Colorado over northern Colorado in terms of snowfall. Strautins said neutral phases make predicting long-term weather patterns more difficult, as reflected by the fact that the weather service’s Climate Prediction Center currently is forecasting an equal chance of above- or below-average precipitation in Colorado through this spring.
For now, however, “we’re in a good spot,” said Strautins, who had been among those closely watching the extremely dry start to the snowpack season.
Jim Pokrandt, spokesman for the Colorado River District, said he doesn’t think anyone predicted the state would be doing this well at this point in the year.
“Let’s keep putting the money in the bank while we’ve got it because it’s so hard to tell what’s going to happen in the balance of the year,” he said.
He pointed to last year, when the snow spigot pretty much turned off for about six weeks in January and February.
“That’s always lurking out there,” he said of the possibility of prolonged dry spells. “Just count our blessings for right now.”
While a wet winter would provide some short-term comfort, it’s going to take more than that for people such as Pokrandt to feel better about the overall water-supply picture in the Colorado River Basin. Water entities in the Southwest are worried about low water levels in Lake Powell and Lake Mead. In the Upper Colorado Basin, the focus is on measures to keep Powell’s water level from falling so low that water no longer can be released through hydroelectric facilities at Glen Canyon Dam. If that were to happen, it would not only prevent hydropower production, but would limit the ability to release water downstream and meet obligations by Upper Basin states to deliver water to Lower Basin states and Mexico.
“In the bigger picture we still have to treat Lake Powell levels as if it’s a near-term emergency and still do the contingency planning that’s necessary to preserve power-generation levels there,” he said.