Avalanche forecast

Hatcher Pass

Hatcher Pass Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

New snow and wind will bring increasing avalanche danger to Hatcher Pass today.

At upper elevations, the avalanche danger will rise to CONSIDERABLE  for  WIND SLAB avalanches. At mid and upper elevations, there is still a chance you could trigger a large PERSISTENT SLAB avalanche on old weak snow near the ground. At low elevations, you may be able to find isolated new snow instabilities in steep gullies and small terrain features. 

Visibility and travel will be obscured by snow and wind today. Lower elevations will hold some protection from the wind and definition in the trees and alders. If you venture into avalanche terrain, watch out for new snow instabilities, which will present on a spectrum from loose sluffs to dense wind slabs. Look out for fresh drifts, cracking and collapsing, and blowing snow. 

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Avalanche problems

  • Wind Slabs

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

    Today's storm arrives with increased southwest winds. This wind will work to transport both new and recent snow into small drifts and larger slabs. As Hatcher Pass accumulates more new snow, starting zones are becoming more connected and capable of producing larger avalanches. 

    Today, expect wind slabs to increase in size, likelihood, and distribution as you climb in elevation. This means at lower elevations and on protected slopes, new and recent snow will present with manageable, dry loose behavior. But as you climb in elevation, wind will work to shape larger, stiffer, and more connected slabs of snow that will be more dangerous and difficult to manage. Look out for cornices, fresh drifts, and round lenses of snow at ridgelines, on cross-loaded gullies, and steep convex rolls. Expect wind slabs to be 1-2' deep and range in density as you gain in elevation and change your aspect to more or less wind exposure.

    New snow is falling on loose dry snow and isolated soft slabs formed earlier this week. Forecasters and public in the field yesterday observed surface hoar on multiple aspects that could provide additional instabilities for this new snow. Approach loaded slopes with caution and remember, most avalanches happen during or within 48 hours of a storm. 

     

    Skier triggered soft slab from yesterday on upper west facing Marmot. 

    Photo: Hatcher Pass Avalanche Center

  • Persistent Slabs

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

    New snow in the last week is testing old buried weak layers at the ground. While we have observed no recent natural or human-triggered avalanches on these layers, the snowpack structure remains poor, and this problem remains possible.

    Additional snow load today will continue to stress these weak layers near the ground. A skier or rider could still trigger an avalanche over 3' deep on weak snow near the ground. This problem is most pronounced on steep, upper elevation slopes where the snowpack remains thin and shallow, as new snow and water weight accumulates, isolated areas at mid elevations could produce the same problem.Small natural or human-triggered avalanches could accumulate weight and step down to these deeper weak layers, increasing the size and consequnce of smaller avalanches. 

    The easiest way to manage this problem is to select terrain with a steepness of less than about 30 degrees. If you do choose to get into avalanche terrain (slopes steeper than 30 degrees), select slopes with a uniformly deep snow pack greater than about 3' deep—although be aware that you could trigger a slide from the edges or the middle of a slope where the snowpack is shallow and variable. 

    Despite a nice February trickle of snow, our snowpack structure remains poor. Even though new snow did not overload this setup (triggering natural avalanches), in areas that harbor shallow structure, you could still trigger an avalanche where old buried interfaces harbor persistent weak layers or deeper in the snowpack in weak, sugary snow above the ground. 

    Photo: Andy Paul

Avalanche Discussion

Hatcher Pass remains in an active pattern with southwest flow bringing us an additional shot of snow today. 

New snow and soft slab reactivity and distribution were overall less than anticipated over the last few days. Still, there are many pieces of untested terrain in the forecast area where mid-storm winds transported snow and slabs were then buried by soft, gentle snow. 

Today, new snow will be falling on this weak dry snow and creating a new round of instabilities. In addition to some previous mid-storm densities, crusts, and wind slabs, forecasters observed areas of surface hoar that could produce sensitivities to new snow today. 

The takeaway is that today’s avalanche problems are mostly centered on new snow and wind. But if you’re committing to steep slopes, don’t rule out the possibility of triggering a larger, more destructive avalanche that fails near the ground.

Lingering persistent slab problems can be frustrating, especially as the season goes on and obvious signs of instability—like cracking and collapsing—become scarce. As we continue to get more snow and the Hatcher Pass snowpack deepens, triggering a slide that fails near the ground will become more difficult. However, we’re not there yet on all slopes. There are still plenty of areas where the snowpack remains thin, variable, and weak.

RECENT AVALANCHES: 

Yesterday, a skier triggered a small avalanche on upper west-facing Marmot. Forecasters in the field over the last two days observed several dry, loose avalanches in steep, craggy terrain and small wind slabs on steep, wind-loaded slopes. These were all small D1s. Friday, a party triggered a D1.5 soft slab avalanche at about 1500 on the W side of Marmot at 4,300' in Tomahawk Alley (between Mid Rib and the Lodge Run. It appeared to have failed where new snow met firm, old wind-affected surfaces in this location and had a crown (see photo below and all recent observations here). 

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