Archived Avalanche Advisory covering Breckenridge, CO for Saturday, Dec 31, 2022 Avalanche Forecast Issued on:Thu, Dec 29, 2022 at 4:30 PM Considerable - Above, at and below treeline You can trigger a large and dangerous avalanche on northwest through east to south-facing slopes, especially at upper elevations. You are most likely to trigger an avalanche from an area of shallower snow, like near protruding rocks, bushes, or at the bottom of convex rollovers. You can trigger avalanches from a distance or below, so give yourself a wide margin around any steep slopes. Carefully evaluate lower elevation and wind-sheltered steep slopes as well. Consider avoiding steep slopes if you find a cohesive slab of snow resting over a very soft, weak layer of snow. If you see signs of unstable snow like cracking or collapsing, move to slopes less than about 30 degrees that are not connected to larger, steeper slopes above. Avalanche Problems (1) Problem: Persistent Slab Aspect/Elevation: NW through E all elevations, SE At and Above treeline Likelihood: Likely Size: Large to Small Persistent Slab avalanches can be triggered days to weeks after the last storm. They often propagate across and beyond terrain features that would otherwise confine Wind and Storm Slab avalanches. In some cases they can be triggered remotely, from low-angle terrain or adjacent slopes. Give yourself a wide safety buffer to address the uncertainty. Issued on:Thu, Dec 29, 2022 at 4:30 PM Northern Mountains Regional Discussion Tuesday and Wednesday's storm came in warm and then temperatures dropped significantly Wednesday night. That left us with right-side-up snow (when a storm starts with warm, wet, and dense snow and finishes with cold, dry, and low-density powder). Snow fell across the entirety of the Northern Mountains in this cycle. The Park Range and Flat Top Mountains did the best, with 18 inches of snow and more on the way. The difficulty now is managing a Storm Slab problem in addition to a Persistent Slab problem. We have not had reports of the Storm Slab being reactive, however, there is more snow in the forecast combined with rising temperatures which may bring this problem to life over the weekend. The Front Range and Summit County may see significant snowfall on Saturday. The timing of the storm and the total amount of snow is still in question but expect to see the avalanche danger rise through the weekend. If these areas get a foot or more of new snow, expect avalanche conditions to become very dangerous. On Thursday, observers found a thin and breakable crust was observed in the Loveland Pass area on high-elevation northerly-facing slopes. This crust had soft facets beneath and new snow above and was very reactive in Extended Column Tests; propagating across the column on isolation twice. As this crust gets buried with additional snowfall and wind-drifting over the weekend, look out for it to begin to produce avalanches. Avalanches triggered in the newer snow can easily step down and become larger and more dangerous. While we are forecasting a rise in danger over the weekend, conditions are still dangerous for Friday. As our persistent weak layers get buried more deeply, it becomes more difficult to trigger an avalanche. However, if you find the right (or wrong) spot you can easily affect the buried weak layers near the ground. You are most likely to trigger these more deeply buried weak layers from a thinner area of the snowpack. If you trigger a slide in one of the shallower spots, it can wrap around terrain features and entrain the entire season's snowpack. New snow makes it difficult to identify thin versus thick areas. The only way you'd know for sure would be to probe the entire slope - not a likely or worthwhile activity. Alternatively, you can avoid areas with protruding rocks or bushes, or the edges of convex rollovers as likely areas of more shallow snow. On Monday, a snowboarder triggered an avalanche on Berthoud Pass and was caught and killed. Our sincere condolences to all the friends and family of the deceased. Additionally, since December 23, there have been at least two close calls with avalanches triggered by one party almost burying individuals in another; one near Marble and one near Berthoud Pass. Avalanches are being triggered remotely, and many people are recreating in the backcountry this holiday season. With the threat of remotely triggering avalanches, you not only need to be aware of overhead hazards for your party, but you should be aware of other parties traveling near you. Strike up a conversation at the trailhead, share what conditions you are seeing, discuss your trip plan, and let's all enjoy safely recreating in these beautiful snow-covered mountains together.