Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

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

A heavier wave of precipitation and wind should result in more avalanche potential on Thursday. Recent avalanches are the best indication of instability and we're starting to see an uptick in those. Slabs will be larger and possibly more reactive as you ascend in elevation or in wind-loaded terrain. 

Problemi valanghivi

  • Storm Slabs

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

    This next storm wave will be the largest of the week, resulting in a bump in avalanche hazard. Use small test slopes, uptrack tests, or quick hand pits to look for failure points within or at the base of this week's storm snow. Cracking, upside-down snow, or blocks failing easily in your tests indicate that a slab avalanche problem exists and you should avoid slopes over 35 degrees. The depth and reactivity of slabs may vary from slope to slope due to exposure to wind. Large drifts, fresh cornices, or stiffer feeling snow can indicate that the wind has created slabs which may be more unpredictable than nearby storm slabs.

    (3/12/2025)

    A shallow slab triggered on Mount Snoqualmie. Expect slabs to be larger and more reactive as you ascend in elevation or wind-loaded terrain.

Avalanche Discussion

In some respects, conditions are straightforward out there. We're not worried about snow below the easily identifiable atmospheric river (AR) crust. So you have a good snowpack marker to target that will put a cap on potential avalanche size. However, the depth and layering above this crust is variable throughout the landscape. In some locations, weak surface hoar is suspected at the 3/9 interface. This leads to uncertainty, meaning you should approach slopes cautiously and gather plenty of data before committing. This variability could result in surprising avalanches.

Wednesday appeared to be a primer and indication of things to come on Thursday. The storm wasn't overly impressive, but a steady trickle of avalanche activity was reported via the Summit at Snoqualmie Pro Patrol and public observations. Many parties used the word "surprising" when describing the avalanches they encountered. Dry and wet avalanche problems, both loose and slab were observed, with the majority of wet problems occurring as temperatures increased midday. We expect a cooling trend with this next wave, which should limit wet avalanche potential. But if lower elevations remain moist or the sun pops out and destabilizes new snow in the afternoon, be on the lookout for rollerballs, pinwheels, and small fan-shaped avalanches.

The flip side is that more snow and moderate to strong winds will only increase the potential size and reactivity of dry snow problems. Based on the activity reported on Wednesday, slabs could fail easily on convexities, unsupported slopes, or wind-affected terrain, particularly after periods of heavy precipitation or wind. 

Regioni coperte