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Tue, January 22nd, 2013 - 7:00AM
Wed, January 23rd, 2013 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

There is a MODERATE danger today below treeline for wet snow avalanches. This concern is on all aspects below 3,000′. There were several small wet slides triggered both naturally and by people yesterday and will likely be the case again today. Above treeline we have a MODERATE avalanche danger for fresh wind slabs around a foot deep as well as the much larger deep slab avalanche.

Tue, January 22nd, 2013
Above 2,500'
2 - Moderate
Avalanche risk
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
Avalanche Problem 1
  • Wet Loose
    Wet Loose
Wet Loose
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
More info at Avalanche.org

Man, what a warm day yesterday. For any folks that were out and about there was a marked change in temperature – and snow quality – in the afternoon. Temperature at 1,900’ (Center Ridge SNOTEL) went from 36F to 39F between noon and 1pm which turned the soft “cream cheese” powder to sticky and difficult riding. There were several wet loose avalanches over the course of the day on all aspects below 3,000’. These were both natural and human triggered but most in the small category and confined to the upper 4-8” of damp loose snow. A few larger wet point releases were seen on the east face of Pyramid. Additionally, small wet slab avalanches were reported on the northern side of the Pass.

Today the warm and rainy conditons continue. We should see a decline in the natural wet activity but human triggered wet loose and possibly wet slab avalanches can be expected on the steeper slopes. These should be fairly small but do have the potential to become larger and more worrisome in bigger terrain where significant amounts of snow can be entrained.

Wind Slab:
Above 3,000’ in the upper alpine, where snow is falling and the wind is blowing, wind slab avalanches will be the primary concern. The moderate to strong easterly winds began to load slopes yesterday afternoon. Shallow 3-6” wind slabs were building easily but were only moderately touchy. These slabs should be thicker today and fairly stiff and stubborn to trigger. However, this is the case where they can lure you onto them before releasing, taking you for a ride. Watching for loaded slopes, cracking in stiff and hollow feeling snow and collapsing will be ways to avoid these wind slabs.

Avalanche Problem 2
  • Deep Persistent Slabs
    Deep Persistent Slabs
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
More info at Avalanche.org

Once again, we are concerned about the deep slab avalanche problem caused by weak early season snow residing in the bottom of the snowpack. The current warm temperatures are adding to this concern today as they can act to loosen the pack as a whole. What this does in a nutshell is increase the deformation in the 3-8′ thick slab which subsequently adds stress to the weak layer below. The good news is the weak layer is becoming deeper and deeper by the day and our pit results continue to show signs that this type of large, destructive avalanche is getting harder and harder to trigger. But nonetheless, we still have to keep this problem in mind.

Tue, January 22nd, 2013

Warm weather continues over the Eastern Turnagain Arm this morning. Temperatures reached a seasonal high yesterday with 32F up to 3,500′ and 40F at 1,000′ €“ downright balmy. Over the past 24 hours we have only had a few tenths of an inch of rain below 1,500′ and a couple inches of snow at the highest elevations. Winds have been moderate to strong from the east €“ averaging 20mph with gusts to over 50mph.

Today warm and wet conditions remain. Ridgetop temperatures should hover around 32F, or just below, and the upper 30’s at 1,000′. A quarter of an inch of rain is expected below 2,000′ and 2-4 € of wet snow above. Expect winds to be around 25mph with gusts to 50mph.

Slightly colder air begins to move in tomorrow. A weak southeast flow should keep cloudy skies and snow flurries (with little accumulation) over us for the next couple of days.

 Kevin will issue our next advisory tomorrow morning, January 23rd.

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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.