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ARCHIVED - Forecasts expire after 24 hours.
Issued
Wed, January 23rd, 2013 - 7:00AM
Expires
Thu, January 24th, 2013 - 7:00AM
Forecaster
Kevin Wright
Avalanche risk The Bottom Line

Unseasonably warm temperatures, with small amounts of rain and snow, are elevating the danger slightly with a wet concern in lower elevations.   MODERATE avalanche danger can be found above treeline for deep slab problems combined with wind slabs at the ridges.   Below treeline is also MODERATE for wet avalanche concerns associated with the above freezing temperatures.  

Wed, January 23rd, 2013
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
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. Dangerous avalanche conditions. 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

Temperatures have dropped a little since Monday, but remain above freezing to around 2000 feet.  Some minor surface stability issues have been noted with the warming temperatures, but nothing has caused great concern.  Riding conditions changed quickly with the warmup.  If it was soft carvy powder, it probably isn’t anymore until you get above the zone that thawed at the surface…

Wind Slab-

Higher up, above 2000-2500 feet, the effects of the warmup will be less noticeable.  In this zone the recent precipitation came as snow and wind has been blowing.  Watch for wind loading and associated wind slabs.  Continued light snowfall today combined with moderate wind will contribute to this problem. 

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

Our old friend that won’t go away is mostly out of sight, but not yet out of mind.  As time goes on and the snowpack gets deeper this problem will likely remain dormant unless one or two conditions are met.  A person could still cause a deep slab avalanche if he or she finds the unlucky trigger point.  This will be an area where the snow depth is thinner, possibly with exposed rocks nearby.

The other factor that will bring us concern would be a large precipitation event.  Our current weak storm system is probably not enough to bring the deep slab problem back to life.  We will talk about it in stronger terms again during a more powerful storm event.

Weather
Wed, January 23rd, 2013

Above the freezing line we’ve been getting a few inches of snow each day for the past few days.   Below freezing line the snowpack is losing depth.

We can expect more of the same weather today with a rain/snow level near 1000 feet and continued light snow.   1-3 inches of snow is possible today with another 2-5 inches tonight.   Wind up high will be up to 35mph from the east to southeast.   The overall trend through the rest of the week looks colder with continued light snow.  

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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.