This is an archived text version of an avalanche bulletin for Aspen Colorado. It is archived for reference in relation to an incident that day. Avalanche Watch Issued: Friday, November 23, 2018 at 6:00 AM Expires: Saturday, November 24, 2018 at 8:00 AM The avalanche danger will rise rapidly on Friday night with an incoming winter storm. The Steamboat and Flat Tops, Aspen, Gunnison, Vail and Summit County, Front Range, and Sawatch zones could reach HIGH (Level 4) on Saturday if the weather forecast verifies. Expect heavy snow and strong winds. Avalanches will be easy to trigger and may release naturally near and above treeline on Saturday. Watch for rapidly changing conditions throughout the storm and make sure to check the avalanche forecast for updated avalanche danger on Saturday morning. Backcountry Avalanche Forecast Sat, Nov 24, 2018 at 7:20 AM Issued by: Brian Lazar Today, Tomorrow, Above, near and below treeline Considerable (3) Dangerous avalanche conditions. Cautious route-finding and conservative decision-making essential. Summary Avalanche conditions are dangerous this morning, and will get worse as the day progresses. Storm totals of 4 to 8 inches of new snow since yesterday morning characterizes most of the forecast zone. Another 6 to 10 inches today, combined with strong westerly wind means you can easily trigger an avalanche in the storm snow today. Slabs will be thickest and stiffest on wind-loaded north and east-facing terrain at higher elevations and could break up to three feet thick in these areas. Cracking in the surface snow is a clearly sign of instability. Reduce your risk by sticking to more sheltered slopes less than about 30 degrees in steepness. This new load is testing more deeply buried weak layers. Avalanches breaking on these weak layers will become easier to trigger as the storm snow drifts and accumulates. You can trigger avalanches from a distance, from the flats, or from below today, so travelling under steep slopes can be dangerous. Avalanches like these from just north of Crested Butte zone are likely by this afternoon in the Aspen zone. Give yourself a wide margin travelling around or under avalanche terrain to account for the unpredictable way these avalanche can break across the terrain. Avalanche Problem Storm Slab Likely Small - Large What You Need to Know About These Avalanches Storm Slab avalanches release naturally during snow storms and can be triggered for a few days after a storm. They often release at or below the trigger point. They exist throughout the terrain. Avoid them by waiting for the storm snow to stabilize. Avalanche Problem Persistent Slab Above-Near Treeline N-E Likely Small - 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 The avalanche danger is rising. Our Thanksgiving storm's snowfall totals around the Central Mountains range from 3 to 20 inches so far, with more snow and wind on tap for today. The north and west portions of the Gunnison zone received the most, with the eastern and southern portions of the Sawatch receiving the least. The Aspen and Grand Mesa zones have 4-8 inches of storm snow so far. As the storm rages on, that avalanche danger pattern will follow the snowfall distribution pattern. More snow means more danger. In the deeper portions of the Gunnison zone where an avalanche warning is in place through 8am Sunday, backcountry travel is not recommended. Elsewhere conservative terrain choices will be essential to safe travel. You can trigger large Storm Slab avalanches breaking below the new snow. Some of these avalanches will entrain old layers, including the entire season's snowpack. Yesterday afternoon skiers triggered multiple avalanches north of Crested Butte. At the time 10 inches of snow had fallen, which gives an early insight into what will happen as the snow accumulates around the region. They triggered some of these slides while on a steep slope. They also remotely triggered a couple slides from flat ground a good distance away from the avalanche paths. Natural avalanches are expected today, so avoid travel beneath large avalanche terrain. With the winds picking up as the day goes on, the loading rates will increase dramatically. In areas where less snow falls, your greatest concern will be triggering a Wind Slab avalanche. Pay attention to the local wind-loading patterns and avoid drifted terrain to reduce your risk.