Archived Copy Front Range Backcountry Avalanche Forecast Tue, Dec 31, 2013 at 5:56 AM Issued by: Scott Toepfer Today Above Treeline - Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully. Near Treeline - Moderate (2) Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully. Below Treeline - Low (1) Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Summary A dusting of new snow early this morning across the zone. Wind speeds have eased, but they are still strong enough to drift snow onto the easterly aspects today. New Wind Slabs are forming on lee aspects ranging from north through east to south. Look for pillows of windblown snow in start zones to the lee of ridges and cross loading around rocks and gullies. An observer west of Rollinsville found touchy Wind Slabs near and just above treeline, while the higher alpine was getting blown out. Natural slide activity occurred on east and southeast aspects near and just above treeline. Wind Slabs will be easy to trigger and could be dangerous if they carry you into trees, rocks, or over cliffs. They could also step down into older Persistent Slabs resulting in a much larger and dangerous avalanche. Avalanche Problem: Wind Slab - At and above treeline, NNW - E - WSW, Likelihood is Possible, Small to Large What You Need to Know About These Avalanches Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas. Avalanche Problem: Persistent Slab - At and above treeline, All Aspects, Likelihood is Possible, Small to Large What You Need to Know About These Avalanches Persistent slabs can be triggered by light loads and weeks after the last storm. You can trigger them remotely and they often propagate across and beyond terrain features that would otherwise confine wind and storm slabs. Give yourself a wide safety buffer to handle the uncertainty. Discussion A couple of natural hard slabs were reported from the Berthoud Pass area Tuesday morning. These were above treeline on northeast aspects. Crowns were in the 2 to 4 foot deep range. One of these ran close to 700 vertical feet. The threat of wind slabs and deeper Persistent Slabs remain the top concerns for backcountry travelers as we move into the new year. The last day of 2013 brought (as of 11 am)) an inch of new snow, with some increasing westerly winds. The current weather will not alter today's avalanche danger or avalanche problems. The recent slide activity is a good illustration of our Persistent Slab problem. There were reports of remote triggered slides resulting from a weak layer collapse that propagated some distance before manifesting itself as a slab avalanche. Sometimes we feel or hear that collapse, but not always. The snowpack is a bit tricky right now. Last week’s storm cycle brought modest amounts of new snow, but strong winds. The danger has been slowly easing, but the danger has not gone away, which can bring on stubborn hard slab avalanches. You may sometimes hear people refer to this time frame as a dangerous moderate. Many tracks on a slope, lots of people pushing new lines across the backcountry, and only the occasional human triggered slide can lull users into a sense of safe avalanche conditions. In reality, this is a good time to be very careful in your terrain choices. Avoid areas where the snowpack thins like a rocky area, lower on the slope, or traveling over a steep rollover. Other areas to avoid are paths that lead to terrain traps like gullies or cliffs. It has become difficult to trigger one of these Persistent Slab avalanches but they are lurking about. You will find them on northwest through north to east aspects that are near and above treeline. Conservative route finding with a wide margin of safety is the best strategy for managing these Persistent Slab issues. Generally 5-10" of new low density snow fell since last Saturday. Wind speeds increased Sunday from the west to northwest. New Wind Slabs are forming on lee aspects ranging from north through east to south. Look for pillows of windblown snow in start zones to the lee of ridges and cross loading around rocks and gullies. An observer west of Rollinsville found touchy Wind Slabs near and just above treeline, while the higher alpine was getting blown out. Natural slide activity occurred on east and southeast aspects near and just above treeline. CDOT reported several explosive-triggered slides in the Seven Sisters north of Loveland Pass. Wind Slabs will be easy to trigger and could be dangerous if they carry you into trees, rocks, or over cliffs. They could also step down into older Persistent Slabs resulting in a much larger and dangerous avalanche.