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Tue, March 5th, 2013 - 7:00AM
Wed, March 6th, 2013 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

The majority of terrain has a generally LOW avalanche danger this morning. As the sun heats up the southerly aspects through the course of the day the danger will increase to MODERATE for cornice falls and wet loose avalanches. Additionally, there could be an old stubborn wind slab or two in steep rocky areas at the upper elevations which will be good to watch out for.

Special Announcements

Our deepest thoughts and condolences go out to the family and friends of Christian Cabanilla who died Sunday in an accident near Haines. There are a few details HERE but they are limited at this time.

There are still 17 spots available at CNFAIC forecaster John Fitzgerald’s free talk on avalanche awareness. This will include the art and science of public avalanche forecasting and will be held at REI in Anchorage tonight, March 5 at 6pm.   Visit REI.com for more information.

Tue, March 5th, 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
  • Cornice
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
More info at Avalanche.org

It looks to be one of those dazzling sunny days in the backcountry. Spring is arriving. Temperatures should be warm and the winds calm. The return of the sun is not only catching some of us searching for our sunglasses and sun screen but impacting our southerly aspects as well. There already exists a variable sun crust that is mainly confined to slopes 35 degrees and steeper (steep enough to catch more of the sun’s rays). However, much of our snow, especially in the Turnagain Pass and Summit areas, has yet to see significant solar effects. If the clouds hold back, today could be the day.

With the expected warm up cornice falls will be our primary concern. These have the potential to be very large and break either on their own or with the added weight of a person. There were many of these monsters overhanging yesterday. It cannot be stressed enough to steer well clear of these both on ridgelines as well as underneath them. I was able to get a closer look at the Magnum cornice fall from Saturday, some photos and details HERE.

Avalanche Problem 2
  • Dry Loose
    Dry Loose
Dry Loose
Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
More info at Avalanche.org

Wet loose avalanches will be a concern today as the sun heats up the surface snow. Watching for roller balls, either triggered by you, your sled or occurring naturally under rocks or trees, will be a sign to move to a more shaded aspect. It is that time of year where aspect is key. East slopes will warm first, then south, then west. Planning your route with this in mind and watching what is going on above you will be good practices as we enter into March and April.

Currently, surface conditions exist of mostly soft settled powder with a bit of wind effect and crusts at the upper elevations. A sun crust from Saturday sits just under the surface on southerly aspects but should become softened today.


Additional Concerns:

Wind Slab:
Upper elevations that have seen a bit of wind in the past couple days should be suspect for lingering slabs. These are likely to be hard to trigger and around a foot deep. Having a good exit route planned if one does pop out will be a good idea.

Persistent Slab:
Magnum’s large cornice fall two days ago shed some light on how our buried weak layers and crusts are behaving in the central Turnagain zone. The fact that the cornice was not able to induce a larger slide was very encouraging. However, as we have been mentioning, regions outside Turnagain are more suspect. These include Girdwood Valley, Placer Valley and Grandview (below 3,000’) where a facet/crust combo exists. Additionally, the Summit Lake area harbors weak snow near the ground as well as mid-pack facet/crust combinations. These are outlier issues but good to keep in mind. Safe travel practices, including limiting exposure time in avalanche paths and runnout zones, is a good way maximize a safe day in the backcountry.

Tue, March 5th, 2013

Yesterday greeted any folks getting out with partly blue skies, calm wind and a very mild spring-like feel. Temperatures reached near 30F on the ridgetops and 40F at sea level. High clouds moved in late in the afternoon but have dissipated overnight.

Today, sunnier skies and warmer temperatures is expected over the mountains and will add to our spring-like weather. Temperatures should be in the mid 40’s at sea level and around 30F on the ridgetops. Winds that have been light from the east have shifted around to the NW this morning and are expected to be variable around 5mph. High clouds are expected to move in late in the day as a large low pressure in the Bering pushes a band of clouds and precip our way for tomorrow.

It looks as though we may get another round of snow and wind beginning late Wednesday through Friday.

Kevin will issue the next advisory tomorrow morning, March 6th.

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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.