Archived Backcountry Avalanche Forecast
Vail & Summit County
Tue, Jan 7, 2014 at 7:04 AM
Issued by: Spencer Logan
	
Above Treeline - Considerable (3) Dangerous avalanche conditions. Cautious route-finding and 
	conservative decision-making essential.
Near Treeline - Considerable (3) Dangerous avalanche conditions. Cautious route-finding and 
	conservative decision-making essential.
Below Treeline - Moderate (2) Heightened avalanche conditions on specific terrain features. 
	Evaluate snow and terrain carefully.

Summary

Recent avalanches provide ample evidence of the dangerous Persistent Slab problem. Large triggered 
or natural avalanches have occurred many aspects near and above treeline. They are becoming harder 
for a backcountry traveler to trigger, but they are also becoming larger and more dangerous. Likely 
trigger spots are areas of shallow snow near treeline, or along the margins and bottom of the slabs. 
Triggered avalanches can break 3 to 4 feet deep and take out most of the snowpack, and spread across 
multiple terrain features. Give yourself a large buffer to handle the uncertainty of how these 
avalanches will break across the terrain.

Strong westerly winds have built fresh Wind Slabs behind terrain features exposed to the wind, and 
slopes that face northeast to east through south. Avalanches have broke 1 to 3 feet deep on these 
slopes. Softer slabs on the surface may disguise slabs that are harder, and will break wider. A small 
avalanche could step down to deeper weak layers and trigger a much larger avalanche.
 
Avalanche Problem: 

Persistent Slab - At and above treeline, NW - NE - SE, Likelihood is Possible, Large to Very 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.

Avalanche Problem:

Wind Slab - At and above treeline, NE - S, 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.

Forecast Discussion

Unfortunately, the second avalanche fatality in Colorado occurred Tuesday. The avalanche was 
triggered on an easterly aspect near treeline in the East Vail area (backcountry near the Vail ski 
area). We extend our sincere condolences to the family and friends affected. We will update the 
Preliminary Report as facts are available. I was working on this Discussion as the rescue unfolded. 
My thoughts seem trite in light of the tragedy.