Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
Open full map
Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

There's still a chance that you could trigger large and dangerous avalanches where you find hard over soft layering 1.5-2 feet below the surface.  A more likely scenario will be triggering small loose avalanches in the surface snow. A weak storm will bring another 3-6" of low density snow with cold temperatures.

Lawinenprobleme

  • Loose Dry

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1

    Watch for triggering loose avalanches on steep, especially on slopes 40 degrees and steeper or above unsupported features like rocks and cliffs. You can use small, inconsequetial test slopes to see how easily the snow slides. If you're in terrain that overlaps with Persistent Slab distribution, you need to manage the risk of that, more dangerous, problem. On those slopes, you won't be able to simply avoid surface instabilities.

    (2/6/2025)

    Small natural and skier triggered loose dry avalanches. Moonlight, ESE, 4,600ft

    Photo: Joe Dellaporta

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1–2

    Whumping collapses are a bullseye sign of unstable snow, and the best clue that you should stick to terrain under 35 degrees. The most problematic areas could be where the westerly wind formed stiffer slabs on leeward slopes last weekend at middle and upper elevations. The safest option for this problem is avoiding it altogether by staying on low-angle terrain or less problematic aspects. 

    The problematic snowpack structure is where you find the recent snow at 4 Finger hardness or greater with an underlying weaker layer of sugar-like facets (or surface hoar). This January Drought Layer (JDL) will be about 2 feet under the snow surface. To find the older drifted slabs from west and southwesterly wind, you'll need to probe or dig to feel for them. These stiffer slabs will likely be under softer, more recent snow. Many slopes don't have much of a cohesive slab over these persistent weak layers.

    (1/19/2023)

    An example of a persistent slab in gladed terrain, like you might be able to trigger.

    Photo: Ryan Minton

Avalanche Discussion

Light new snow accumulations won't do too much to change avalanche danger. On Thursday, observers reported small natural and triggered loose dry avalanches on steep, sunny slopes. By afternoon, these aspects formed a thin crust.

While we don't have many observations of Persistent Slab avalanches in the Stevens Zone, there have been many in other zones to the north and south. Locally, observers have reported a "scary" snowpack structure. It's now waiting for the right load to become more active.

From the 31st-2nd, about 2ft of snow fell on widely varying surfaces. Through the 6th, light snow has gradually accumulated to total another 9". Sun on the 6-7th brought down small loose avalances and formed thin crusts on sunny slopes. While many tests and observations show a lack of slab cohesion, we remain concerned with lingering instabilities on the January Drought Layer (JDL) on northerly aspects. Observers have reported many whumpfing collapses, as recent as the 5th. Both the sun and time since the storm of January 31st are allowing slabs to slowly gain cohesion, setting the seen for more consistent slab-weak layer structure. Theses peristent slabs could become more problematic with the next significant snowfall. The main takeaway from the current snowpack is that it is weak, and it's difficult to determine where you are more or less likely to trigger persistent slab avalanches. Avoid a "stepping out" mindset, until we have better confidence with these tricky conditions.

An NWAC Forecaster was in the Henry Creek Area on Sunday. They experienced numerous localized collapses and found two layers of concern in snow profiles. The deepest layer is buried 20-23in down and consists of 1-2mm faceted grains over the 1/10 crust. Above that, buried 15-20", is the surface of the January Drought Layer, which is 1cm buried surface hoar over another layer of 1-2mm faceted grains. There was also a deep but narrow crown on a steep southern aspect at 5700ft, likely a wind slab that occured during strong winds on Saturday. 

You can help us build the forecast by submitting an observation HERE or via the Avy App. 

Abgedeckte Regionen