ARCHIVED - Not the current avalanche danger. This is an archived text version of the advisory issued for the Anthracite Range in Colorado by the CAIC, a state agency. It is archived for reference in relation to a fatal avalanche incident on Feb 11, 2024. Avalanche Forecast Issued on:Fri, Feb 9, 2024 at 4:30 PM Lat: 38.815, Long: -107.133 Sunday, Feb 11 3 - Considerable - All Elevations Our recent storm created dangerous avalanche conditions on most steep slopes. Slopes with wind-drifted, stiffer slabs are most dangerous. Look for drifts of snow below ridgelines, and in cross-loaded features even at lower elevations. You can trigger avalanches from a distance or below, even from flat terrain. So be aware of steeper overhead terrain and give these slopes a wide buffer. Slopes less than about 30 degrees with no steep terrain overhead offer the safest riding. Avalanche Problems (1) Problem: Persistent Slab Aspect/Elevation SW and S above treeline All other aspects - all elevations Likelihood: Likely Size: Large to Very 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 Issuedon:Fri, Feb 9, 2024 at 4:30 PM Lat: 38.815, Long: -107.133 Central Mountains Regional Discussion Weak layers are ubiquitous across the Central Mountains. The variety spans from a problematic surface hoar layer on colder, shadier, protected slopes, to buried near-surface facets, to crust-facet combinations on sunnier slopes. The stiff slab needed for dangerous avalanches is not as widespread, and seems to be confined to wind-drifted areas. But the recent strong winds means you can still find stiffer slabs on many wind-affected slopes. Slab formation is possible at all elevations depending on how exposed the terrain is to the wind so don’t let your guard down. Wind-sheltered slopes are still a concern in areas that got more than around 20 inches of recent snow, because of the sheer volume of snow that has fallen. These slides in sheltered terrain will be relatively smaller, but could still bury or injure you especially if you get carried through trees and other obstacles. A pair of backcountry skiers both got caught, one partially buried and one fully buried near treeline on Hayden Peak on February 7th. Then on February 8th, a snowmobiler on the Grand Mesa was fully buried when a small but steep slope released under her machine. Luckily these incidents had a good outcome with both parties being ok, but it is a stark reminder that we need to be making conservative terrain choices. We appreciate the parties' willingness to share their experiences. The Sawatch Range received the least amount of snow, but enough that westerly winds will move it around and create problems. Easterly facing, wind-loaded slopes above treeline are the most dangerous since that is where the loading is, but don’t discount terrain near treeline as I previously mentioned. Slopes where you find less than about ten inches of recent snow can offer safer travel options as the weak layers seem to be supportive of that load. These areas can be found below treeline in many places and intermixed throughout the range where snow totals were less. The avalanche conditions are dangerous right now, it is not the time to be taking chances in big terrain. There are plenty of lower-angle terrain options out there for us to enjoy while the snowpack adjusts to the recent snow. Consider your travel routes carefully.