Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Light rain and snow with a weak overnight freeze should maintain some danger for wet loose avalanches on Thursday. Once the surface crust has thawed out and you can sink in up to your knee in deep, mushy snow,  it's time to move away from steep slopes. Later in the day, an incoming front should bring stormy weather and form small wind slabs at higher elevations. 

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    With a weak overnight freeze and light rain and wet snow, wet loose avalanches should continue to be the main problem on Thursday. First thing in the morning, check to see how well snow surfaces have frozen. If theres no surface crust, or you sink up to your knee easily in wet snow, than you probably trigger wet loose avalanches on steep slopes. Look for rollerballs, tree bombs, and feel for heavy wet snow as indicators that you can trigger slides. Use small test slopes to see if the wet snow entrains into larger slides. Cornices, water ice, glide avalanches, and other chunks of snow could continue to shed from ridges and rocky areas as they have been reported the past handful of days.

    Be aware of the terrain size you are going into, and consider large complex terrain could fully anything that comes down into the gullies.  get hit by a falling hazard or wet loose slide in large, complex terrain.

    (3/21/2023)

    Wet loose avalanches were easily triggered at lower elevations on Tuesday. E aspect at 4,600ft.

    Photo: Matt Primomo

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    Once a few inches of new snow has fallen and the wind blows, small wind slabs may become possible at uppermost elevations. Earlier in the day, they probably won't exist. Look for these to begin forming more quickly towards the late afternoon as a front pushes through. Look for wind blowing snow as a sign that slabs are forming. 

    If you find deep drifts or observe shooting cracks then steer away from steeper slopes. You can also use timing to your advantage on Thursday, by planning for increased danger later in the day.

    (3/4/2023)

    Wind slab avalanche on the west side of Herman Saddle at 500'.

    Photo: NWAC Public Obs

Avalanche Discussion

An incoming front will begin to add snow to our snowpack. Many surfaces will have a crust, those that don't probably face NW-NE and are near or above treeline. The new snow may bond fairly well initially to old surfaces, but as more and more snow adds up into Friday this could change. For Thursday, expect the lowest danger first thing in the morning. As the daytime warms up wet loose slides may become possible, and later in the day wind slabs may form at the highest elevations. Use timing to your advantage while planning your day. As the new snow begins to pile up, we expect dangerous conditions to develop for at least at the upper elevations on Friday.

For the past week, we've seen a pronounced warming trend, and ongoing rounds of wet avalanches. Tuesday and Wednesday we've seen glide activity really ramp up. See photo below of a large glide west of Stevens Pass taken on Wednesday. On Tuesday, observers in the Skyline and Rock Mountain areas were able to trigger wet avalanches up to size D2. There were some natural wet avalanches near and above treeline. Observers reported, reported natural wet avalanches to size D2 that ran over the weekend on steep, south aspects. Wet avalanches have mostly been on E-S-W aspects, though a few have occurred on steep northerly aspects where snow has fallen off of cliffs or trees. 

A handful of very large D3 avalanches occurred on the 10th and 11th in steep, rocky, and mostly wind-loaded terrain above treeline. These were suspected to have run on the Valentine's Day Crust but we haven't been able to confirm this. Between 2/28-3/6 we received reports of triggered avalanches, up to size D2, that likely ran on the Valentine's Day crust.

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