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ARCHIVED - Forecasts expire after 24 hours.
Issued
Fri, January 31st, 2014 - 7:00AM
Expires
Sat, February 1st, 2014 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger is MODERATE  both above and below treeline:

Above treeline –  On all aspects above 3,000′ in elevation the possibility remains for triggering a deep slab avalanche. This type of avalanche is becoming harder to trigger, yet if one does release it could break full-depth and be unsurvivable. Wind slab avalanches are also possible at this elevation zone and should be shallow and fairly easy to identify. Watch for areas with wind drifted snow.

Below treeline –  In areas below 3,000′ the snowpack is freezing from the surface downward. However, wet and weak snow still remains below the surface crust. Triggering a wet slab avalanche has decreased significantly but until we have a solid refreeze on all aspects it cannot be completely ruled out.  

Even though the cool weather is helping to stabilize the snowpack, don’t forget to use safe backcountry travel protocols. For example, only exposing one person at a time and always have an escape route planned.

Special Announcements
  • The deadline for the Rob Hammel Memorial Scholarship Fund is tomorrow!  Take advantage of this excellent opportunity to start or continue your avalanche education with a scholarship sponsored by  The Friends of the CNFAIC and the Rob Hammel family.  Go to this page for more information  on the scholarship and to learn more about Rob Hammel, friend, colleague and backcountry enthusiast!

  • Coming up on Saturday, February 8th is the Hatcher Pass Avalanche Center 2014 Fundraiser. Tickets are selling fast so get yours today and support avalanche information in the Hatcher Pass area!!
Fri, January 31st, 2014
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. 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

With the sunny skies and increasing daylight hours, travel to the upper elevations in search of dry snow may be on some folk’s mind (if you are willing to brave the crust in order to get there – and back). Snow cover above 3,000′ has greatly improved after the January onslaught and is capped with 4-6″ of soft snow. The exceptions are those areas that avalanched to the ground. The last known deep slab was six days ago on Goat Mtn.

The reason we had such a widespread large avalanche cycle with slides breaking full-depth was because of weak snow near the ground that formed in November and December. We are four days past the end of the cycle yet it is still uncertain how well the weak faceted snow is adjusting to the new load. We know it is buried over 3 feet deep and likely much deeper in areas. This makes triggering a deep slab avalanche hard but it is not out of the question. Thin spots in the slab are the most likely trigger areas and can be commonly found near rocks and scoured terrain features.

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

Though the deep slab problem is by far the most concerning due to the potential consequences, wind slabs will be the most likely avalanche issue encountered above 3,000 feet. We found a few of these yesterday on all aspects yet they were quite small (around 2″ thick and 10′ wide). They were very reactive however and if you are traveling in the upper elevations where dry snow exists, I’d be on the lookout for any fresh wind deposited snow, especially that which is sitting on a slick surface. 

Additional Concern
  • 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

With almost three days now of below freezing temperatures the pack is developing a healthy crust on the surface. These conditions are confined to elevations below 3,000′. Yesterday we dug (or maybe chopped is a better word) into the crust at 2,500′ and found it to be 1 foot thick. Underneath it remains 1-2 feet of wet and weak snow. The area we looked at yesterday was shaded and a place suspected to have a thicker crust than southerly slopes where Kevin dug two days ago. Check out Kevin’s video that shows just how weak the wet snow is.

This ‘hole’ (akin to an ice fishing hole) give a sense of the thick crust over wet snow situation (2,500′, W aspect).

 

Though the crust is getting thicker by the day and triggering a wet slab avalanche below treeline is becoming unlikely, we do have an unusual set up. As the ol’ timers say – unusual things can happen with unusual situations. Wet slabs with a crust on the surface have occurred before.

All that said, the greatest hazard below 3,000′ is slide for life conditions. 

 

Weather
Fri, January 31st, 2014

Yesterday’s weather consisted of blue bird skies, cool temperatures and light Northwest winds. Temperatures at 1,000′ were in the mid 20’s F and the upper teens at 4,000′.

Today is expected to be very similar. Skies have remained clear overnight, excect for some patchy fog in low-lying areas. A slight inversion is setting in and temperatures this morning at sea level and the ridgetops are both in the mid 20’s F. We should see a slight warm up to around 30F below treeline during the day. Winds are expected to remain around 10mph on ridgetops from the Northwest.

As for the extended forecast – it looks like this blocking high pressure will remain over mainland Alaska through the weekend.

Warmest January on record? With two weeks of rainy weather and at least one all time high temperature in the Girdwood Valley, we may just break the record for the warmest January. More on this in the next couple days.

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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.