Storm set to break Summit County’s dry spell with as many as 7 inches predicted Thursday
March 22, 2017
It's been an unusual snow season, to say the least. After a dry October and November that saw snowpack levels well below annual averages, the hand-wringing abruptly ended with strong showings in December and January that more than made up for the sluggish start.
For February and March, however, the pendulum has swung back: Summit's last major snow day came in early March, and the rest of the month has been unseasonably warm.
In Breckenridge, snowpack for those months was down 19 and 54 percent, respectively, after two straight months of totals that were as much as 86 percent higher than normal, according to independent snow measurements.
A brief respite is forecast to arrive, though, and some local ski areas are expecting as much as a half-foot of snow overnight on Thursday.
The storm is expected to arrive in earnest during the day Thursday, when Arapahoe Basin Ski Area, Copper Mountain Resort and Keystone Resort are projected to see an inch of daytime accumulation while anywhere from 1 to 3 inches are forecast for Breckenridge.
The snow is then predicted to rapidly intensify overnight, with 3 to 5 inches expected to fall at Keystone and Copper Mountain and as many as 7 at A-Basin and Breckenridge.
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"The main message is that the best time for powder will be on Friday morning and that most mountains should receive 4 to 8 inches, with some areas receiving 12-plus inches mainly near and east of the divide," meteorologist Joel Gratz wrote on OpenSnow.com.
The prolonged lull has steadily eroded above-average snow totals, which have declined to near baseline level from January peaks of close to 150 percent compared to annual averages.
March is typically a month of frequent storms, but clear skies and temperatures as high as the low 60s mean a lot more snow has melted than accumulated.
A Natural Resources Conservation Service snow-monitoring site at Copper Mountain, for instance, has lost 7 inches of snow in the past week.
The trend is much the same in the northern mountains, where the Steamboat Pilot and Today reported that rapid melting caused flow rates in the Elk River to reach a peak of 1,050 cubic feet per second on March 20, nearly doubling the record for the previous date.
Summit County saw an uptick in melting as well, with 129 cfs flowing into Dillon Reservoir on March 19 compared with 80 to 85 cfs earlier in the month, according to Denver Water.
"This is not unusual for this time of year as we commonly see warm spells like this in early spring," a spokesman said in an email. "With the forecasted storm for tomorrow (Thursday) evening and the weekend, we expect the inflows will decrease back down to the 90 cfs we typically see this time of year."
All of that melting has had an impact on avalanche conditions in the backcountry. The risk of slides is currently moderate — or two on a scale of five — at all elevations on south, southeast and southwest facing slopes.
"The snowmelt creates percolations in the snowpack, and it's not a time you want to let your guard down," said Ethan Green, executive director of the Colorado Avalanche Information Center. "The melt water drains down into the layers, and depending on the route through the snowpack it can create different instabilities."
Areas with steep, rocky terrain can be particularly prone to avalanches during these warm conditions. Those loose, wet slides will typically start near the surface but can quickly break into lower layers and grow considerably, according to the CAIC.
How the new snow will affect the avalanche outlook isn't quite clear yet, Green said.
"It depends on how it comes in, and if it gets cold before the snow comes, we'll have new snow issues. If it doesn't get cold, the wet slide issues will persist."
Meteorologists predict a dry interlude on Friday and most of the day Saturday before another, smaller storm system is expected to roll through and deposit at least a few inches, according to Open Snow.
"There are a few more storms showing up in the forecast," Green said. "It's been slow, but there's still hope."