ARCHIVED AVALANCHE ADVISORY This is an archival text-only version of the advisory in effect at the time of an incident. Colorado advisories are issued by the State of Colorado. Avalanche Warning Issued: Friday, December 24, 2021 at 6:00 AM Expires: Saturday, December 25, 2021 at 12:00 AM An Avalanche Warning is in effect for most of the mountains in Colorado. Heavy snow and strong winds are creating very dangerous avalanche conditions. Expect very large avalanches to run naturally and long distances on Friday. Travel in avalanche terrain is not recommended. Backcountry Avalanche Forecast Fri, Dec 24, 2021 at 6:57 AM Issued by: Jason Konigsberg Friday Above Treeline and Near Treeline High (4) Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Below Treeline Considerable (3) Dangerous avalanche conditions. Cautious route-finding and conservative decision-making essential. Summary Heavy snow and strong winds are creating very dangerous avalanche conditions. The most dangerous portion of the zone is in the north around Cameron Pass and Rocky Mountain National Park. This is where the most snow is falling. Avalanches can release naturally and run long distances. Pay attention to what is above you and avoid traveling under steep slopes, especially those that face a north through east direction. Even if you find an area with less snow and less dangerous conditions, winds are building thick slabs near ridgetop so avoid these areas. Avalanche Problem Persistent Slab N - NE - E Above and Near Treeline Possible Small to Large What You Need to Know About These Avalanches 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. Forecast Discussion Fri, Dec 24, 2021 at 8:14 AM Issued by: Jason Konigsberg An Avalanche Warning is in effect and the avalanche danger is HIGH (Level 4 of 5) across the Northern Mountains. At around 8 AM, storm totals are anywhere from 6 inches to 18 inches. The favored areas, and also the most dangerous, are the Park Range, Flat Tops, and Never Summer Range including RMNP. There are some places with only about 6 inches of snow such as around the Vail and Beaver Creek area, so the danger around these areas is currently lower, but we do expect continued heavy snowfall throughout the day. So even if you are traveling in an area that seems safer due to lower snow totals, be prepared for changing conditions as the day progresses. This is not a normal storm for Colorado. The snow is very dense and even wet in places. This dense snow makes for well connected slabs. If you have been following the forecast over the last few weeks, you will know that we have well connected weak layers, but prior to this storm we did not have the slab. Now we do. Mitigation work around the highways this morning are finding avalanches to propagate long distances and be surprisingly wide. The storm is ongoing, so throughout the day expect conditions to worsen as avalanches break wider and deeper and run further. If the dense, slab-building snow wasn't enough to exacerbate avalanche conditions, we also have wind speeds that are perfect for transporting snow. At upper elevations winds are generally in the 20 to 30 mph range gusting into the 40s and 50s. They are also from a west to southwest direction which will load the slopes that we are most concerned with. Thick slabs building on northeast to east-facing slopes, where there are deeply buried weak layers, will fail dramatically. The only limiting factor right now is the thin cover in the paths, otherwise we would see avalanches running thousands of vertical feet. Regardless, these avalanches will be plenty large enough to bury a person. As the natural cycles comes to an end with snowfall, dangerous avalanche conditions will remain through the weekend. Don't underestimate the avalanche danger as it drops to Considerable (Level 3 of 5) tomorrow. It will still be easy to trigger large, wide and potentially deadly avalanches.