Avalanche forecast

Hatcher Pass

Hatcher Pass Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

The avalanche danger is CONSIDERABLE for WIND SLABS above 3500 ft. The avalanche danger is MODERATE for PERSISTENT SLAB above 2500 ft. 

Since Sunday, Hatcher Pass has seen over a foot of new storm snow and strong gusting extreme winds. 

Human triggered avalanches will be likely at upper elevations and possible at mid elevations. Natural avalanches are unlikely today.

SPECIAL ANNOUNCEMENTS: 

Areas throughout the state have received multiple feet of snow and many regions have considerable or high danger. Many areas do not have public avalanche forecasts. Check out avalanche.org to find your local avalanche center. Be sure to assess the snowpack before entering avalanche terrain. 

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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    The 1/12-1/13 storm event blew almost as hard as the 1/6-1/7 storm event.  Sustained SE winds in the 40s-50s with gusts 70-89mph were recorded at Marmot and Hatch.

    Expect new wind slabs 1-2' thick likely to human trigger on southwest through north facing slopes above 3500 ft generally 35° and steeper. It will be possible to find shallower wind slabs at mid-elevations. There is a good chance that wind slabs triggered today could step down into old buried weak layers of the snowpack, increasing the size, complexity, and danger of this problem.

    While you are most likely to encounter wind slabs on leeward aspects today, do not be surprised to find touchy wind slabs on cross loaded easterly aspects. You could encounter these at mid to upper elevations. Most south/southeasterly aspects appear stripped of snow. 

    Watch for stiff or hard drifts and use caution when approaching smooth rounded features.  Wind drifts may sound hollow or crack out from your ski tip as you travel across them.  Shooting cracks are signs of instability and indicators of this avalanche problem. 

    Confidence - This has been a long-duration system of storms and as such we have reduced observations from the field. With uncertainty around the distribution and reactivity of wind slabs that were building yesterday, we reccomend a conservative mindset and cautious approach when entering the field. While new storm snow will be settling with cooler temperatures and calm winds, it may still be possible to find lingering storm slabs over weak, loose snow at mid and even lower elevations today. Be mindful of terrain traps such as gullies and drainages. 

    Wind slabs and storm slabs were easy to find and trigger at mid elevations yesterday. 

    Photo: Andy Paul

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    The bottom of our snowpack is composed of relatively widespread basal facets and above that, various layers of facets above and below crusts and old wind slabs. This poor structure has been put to the test by 1.5" of water and 9-11" of new storm snow in this last storm event (1/12-1/13). Because of wind and new snow load, persistent slabs are more widely distributed than previously and are not only on leeward aspects. It may be possible to find deeper, more consequential persistent slab avalanches in areas where buried hard slabs are below heavier, wind drifted snow. 

    A more consequential persistent slab avalanche 1-3' deep will be possible to trigger above 2,500' on slopes 30 degrees and steeper at mid and upper elevations. 

    The distribution of this problem at this time is potentially widespread. We have been tracking hard, buried slabs built by the 1/6-1/7 storm event that brought a mere 3-5" of snow to Hatcher Pass but blew 90+mph. These slabs are now buried under new storm snow, and new wind slabs formed by 80+mph winds from the more recent storm. This is all stressing weak, sugary snow in the middle and bottom of the snowpack. 

    Observations have been limited since the conclusion of yesterday's storm, but we do know that this problem is in play and will continue to linger. Propagation in test pits has been easy to find and new snow soft slabs have failed easily on midpack facets. Remember, it is possible to remotely trigger persistent slabs and  that the majority of avalanche fatalities are associated with this problem. We are also most likely to see feedback on it as the winds calm and skies clear this week. 

    Utilize scoured terrain on ridges for uptracking, mind your exposure by traveling one at a time. Hard slabs over persistent snow grains (like facets and basal facets/depth hoar) have higher consequences, despite our relatively low snow season. 

    Stiff, and thick (up to 3'/1 meter) pencil hard slabs formed by 1.6/1.7 winds are easy to find in previously wind loaded features at mid and upper elevations. These slabs are now buried by the last storm and are sitting on various faceted layers and weak, basal facets. 

    Hard slabs over persistent grains (like facets and basal facets/depth hoar) have higher consequences, despite our relatively low snow season. 

    Photo: Andy Paul/Alaska Avalanche School

Avalanche Discussion

RECENT AVALANCHES: 

Yesterday, we were able to trigger wind slab avalanches on small test slopes in crossloaded, mid-elevation terrain. Read the observation here. 

A party triggered a soft slab avalanche yesterday on President's Ridge that broke 1-2' deep and ran about 400'. This consequential slide is a great example of the intersection of our problems, being a wind slab problem that behaved with persistent slab qualities found on a cross loaded gully feature in otherwise windward terrain. Check out the rider's observation here.

Two days ago, a party and their dogs were caught and carried in a wind slab avalanche in April Bowl on the back side of Hatch Peak. See obs HERE. 

Regions covered