Turnagain Pass Avalanche Forecast

Why you should still be concerned about PERSISTENT SLAB AVALANCHES (In our current case: Hard WIND SLABS SITTING ON WEAK SNOW): Variable snowpack depth, hard slabs, persistent weak layers, and slopes that haven’t slid. The likelihood of triggering an avalanche is decreasing but depending on the specific slope the consequences could still be high. Things to remember today…

1) Its been 5 days since a big wind event loaded Northern aspects and cross loaded many Eastern aspects. This wind event as well as the Christmas snow storm caused widespread avalanching in the area. Avalanches were 1-3′ deep and large enough to kill or injure a person. Slopes that did not slide in either event should be approached with caution. Always consider how large a slope is and what other terrain it is connected to. Triggering a slab from below is still possible, especially on a snowmachine.

2) Several persistent weak layers are buried within the snowpack (facets and buried surface hoar), but strong supportable snow over top is making it stubborn to trigger.  The snowpack depths across the advisory region are variable. In the areas where a thinner snowpack exists several observers have experienced collapsing/whumpfing in recent days. Including an observer who felt/heard a loud collapse followed by a fast moving shooting crack on their second ascent up Max’s Mountain on Sunday. It may be easier to find unstable snow in these areas. The tricky part is that obvious signs like cracking and ‘whumpfing’ are becoming less common in the Turnagain Pass area and may not be an early warning sign that a slope is still dangerous. 

3) Look for hard snow over soft snow – slabs can be strong enough to support the weight of a snowmachine or skier, allowing you onto them before they release. It could also be the 1st or 5th or 12th person or machine on the slope that tips the balance. Slabs on unsupported slopes in steep rocky terrain are prime suspects. Thin spots in the slab are likely trigger points. Always practice safe travel techniques in avalanche terrain.

• Expose one person at a time
• Watch your partners
• Have an escape route planned
• Watch for other groups
• Consider, what will happen if the slope slides? 

Wind slab that propagated in a snow pit yesterday on Eddies on a Northerly wind loaded aspect. 

Avalanche on Magnum from the 12.30.16 wind event. Example of slide with high consequences and adjacent slopes that may still harbor a dangerous snowpack. 

The warm, above freezing temperatures at the ridge tops for over 36 hours is unusual. The snowpack has been settling steadily due to the temperatures and the Tincan Snow Profile Monitoring is showing that the snow near the surface is gradually warming. However, radiation is minimal at this time of year, no melting has been observed and clear nights with low humidity have allowed for radiant cooling. What does this mean for you traveling today? Probably not much but there is a chance that the settlement and warming have affected the slab character and could make triggering a little easier.