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ARCHIVED - Forecasts expire after 24 hours.
Tue, February 4th, 2014 - 7:00AM
Wed, February 5th, 2014 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

The majority of terrain in our forecast zone continues to have a LOW avalanche danger. The exception is the elevation band above 3-3,500′ where dry snow exists. At this uppermost elevation there is a MODERATE danger for triggering a deep slab avalanche, wind slab or potentially a shallower slab sitting on faceted snow 1-2′ deep.

Below the 3-3,500′ elevation band where the danger is LOW a very hard crust is present creating slippery slide-for-life conditions.

Tue, February 4th, 2014
Above 2,500'
2 - Moderate
Avalanche risk
1 - Low
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
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
  • 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

Though the majority of terrain in our forecast zone is below 3,500′ and frozen solid as a rock, there are areas, like Pastoral Peak, that are high enough to have dry snow. At these locations there is an old weak layer of facets (the November snow) buried 3-6+’ deep. Although this layer is buried fairly deep and has had a week or more to adjust to the load placed on it during January, it is still there and therefore a concern. If someone finds just the right thin spot and a deep slab is triggered it could produce a large and destructive avalanche. The likelihood for this is low but the consequences can be high. 

Avalanche Problem 2
  • Wind Slabs
    Wind Slabs
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

Keep an eye out for old and stiff wind slabs at the high elevations and peaks. Though the wind has picked up a bit during the past 24-hours to the 10-15mph range with gusts into the 30’s there is little snow to transport. However, as with any travel in exposed areas with dry snow, finding a wind slab can be possible.

Additional Concern
  • Announcement

Another concern that may be developing at the very upper elevations in the dry snow (above 3,500′) is faceting surrounding one or more crusts. This is in the top 1-2 feet of the snowpack. During the tail end of our wet January weather (Jan 26-28) the rain/snow line fluctuated around 4,000′ and we know there is at least one crust that was formed up to 4,500+’. This is 6-8″ below the surface and was seen on January 30th – more details can be found HERE. With almost a week now of clear and cool weather I wouldn’t be surprised to find facets developing around the crust. If this is the case, triggering a slab avalanche breaking in a weak layer near a crust could be possible. This is something to think about and look for if you are venturing to the uppermost elevations.

If anyone does head up to these areas, we want to know what you are seeing – send us an observation!

Tue, February 4th, 2014

During the past 24-hours we have seen mainly overcast skies and mild temperatures. Ridgetop temperatures have averaged in the low 20’s F and the mid 30’s at sea level. Ridgetop winds have been mainly from the East with averages in the 10-15mph range with gusts to 30mph.

Today we should see cloud cover begin to clear and possibly some sunshine. Temperatures look to drop a hair today with highs around 20F on the ridges and 30F at sea level. Ridgetop winds should remain in the 10-15mph range from the Southeast.

Looking to the latter part of the week we have a chance for a few flurries to a few inches of snow on Thursday night into Friday. This is associated with a small system developing over PWS. Along with the potential snow, winds will be increasing and we will return to our blocking high pressure for the weekend. The NWS has posted a Special Weather Statement – though you may not want to read it…

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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.