Avalanche danger in the Summit County area spiked this weekend, as more than 8 inches of new snow loaded up weaker layers at the base of the snowpack.
Given the current conditions, experts warn of dual dangers: smaller, but more easily triggered slides in the new, loose snow and bigger, more destructive avalanches, that occur when persistent slabs give way.
"It will be pretty easy to trigger slides in the new and windblown snow. Those slides by themselves will probably be pretty manageable," Colorado Avalanche Information Center (CAIC) forecaster John Snook said. "The bigger problem is that we're putting new weight on the preexisting snowpack."
Wind and snowfall over the last several days have created large slabs, adding stress to the deeper snowpack and prompting CAIC to issue a special advisory for all mountain areas Sunday.
Several human-triggered avalanches in areas that didn't show many signs of instability underline the danger, according to the advisory. Summit County had two reported slides in the last 10 days, one inbounds at Arapahoe Basin and a second triggered by a backcountry skier on Peak 1.
Neither involved fatalities.
"We knew this weather was coming in and we expect to hear about more avalanches today," Snook said Sunday. "We're still trying to get the message out there, telling backcountry travelers to be careful."
The avalanche danger is rated considerable on most slopes at and above tree line, the third on a five-tiered scale used by CAIC. Danger ratings in the Sawatch Range directly south of Summit County was upgraded to high this weekend, after Monarch Pass received significant snowfall.
Part of the problem this season, experts say, has been the changes in conditions across relatively small distances. Snow that appears safe in one area may be unstable very nearby, leaving backcountry recreationalists unprepared or unaware of potential escalations in avalanche danger.
"The big lesson this year has been the variability of the snowpack," Summit County Rescue Group spokesman Charles Pitman said. "There are several weak layers buried within the snow. Individuals that go in the backcountry really have to be prudent about understanding the snow conditions right where they are."
Pitman urged backcountry travelers to frequently check snow conditions and to carry and know how to use avalanche safety equipment, including probes and beacons.
Precipitation is expected to continue this week, paired with colder temperatures for the first part of the week.
National Weather Service forecasters are calling for sunny skies today, followed by a 40 percent chance of snow tonight, although accumulations aren't expected to amount to more than half an inch.
Snow is possible throughout the day Tuesday and could return Wednesday night into Thursday, according to NWS forecasts. Snow accumulations for the coming week are uncertain, but aren't expected to rival this weekend's totals.
Up to date weather and avalanche forecasts are available online at www.weather.
gov and www.avalanche.state.co.us.