Bollettino valanghe

East Slopes North

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

We're transitioning from hot and sunny to more seasonable weather in the East North.  Wet avalanches will be possible until the snow surface has enough time to thoroughly freeze and stabilize. Make travel plans that minimize your exposure to wet surfaces and overhead cornices.

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Wet avalanche activity should be trending downward. It may not be eliminated, however. Watch for rollerballs and moist snow as signs that you could soon see wet avalanches. You can avoid triggering avalanches by moving to more shaded or lower-angle slopes. Time your travel to be off slopes before they become wet and weak. Put a terrain buffer between your group and large start zones or complex avalanche paths above 6,500ft. Use extra caution when you find less than 5 feet of snow. Facets buried throughout February exist over a crust 2-4 feet below the surface.

    Avalanches could vary in size and consequence. Loose wet avalanches may be small. Wet slab avalanches could occur in the recent snow in the top foot of the snowpack, or they could break widely across large terrain features on weak layers buried as much as 3 feet below the surface. The chances for large avalanches could increase by midday and afternoon if the surface crust breaks down.

    (3/15/2024)

    Recent widely propogating avalanches on a ridge between Tower Mountain and the Needles. E aspect at 7000'

    Photo: Willie Webster

  • Cornices

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    Be mindful of the potential for cornices to sag and fail on slopes overhead. When traveling on ridges, keep plenty of distance from the edge and ensure you're not traveling on overhung snow.

    Cornice falls are difficult to predict. They're a hazard in their own right, but they can also trigger avalanches on slopes below. Avoid lingering underneath these behemoths; they're erratic and can fail at any time of the day, sometimes long after the height of warming. 

    (4/4/2023)

    An example of cornices near Blue Lake and Stiletto Peak from a previous season.

    Photo: Willie Webster

Avalanche Discussion

Temperatures are expected to continue to fall as wind and the chance for precipitation increase. This should help the likelihood of avalanches decrease as the snow surface begins to freeze and stabilize from the top down. We're not exactly throwing the snowpack in the freezer, however. The potential for wet and shedding-style avalanches will continue until a stout surface crust has developed.

Since the 14th, observers reported natural wet avalanches on steep, sunny slopes up to size D2. The most recent large slab avalanche was reported on Sunday in Willow Creek, WNW, 7,200ft. This occurred on an unsupported slope, possibly due to snow shedding from overhead cliffs, and it likely ran on either a weak interface from March 9th or layers buried in February.

On the 16th, an NWAC observer got an aerial overview of recent avalanche activity and cataloged numerous large to very large slab and wet avalanches. We suspect many of these slab avalanches ran on the March 9th interface, while the deeper slides were likely on facets above the Jan 31st crust. Several small wind slab avalanches and numerous large to very large persistent slab avalanches were also noted in the second half of last week (see photos below).  From 3/9-12, the Harts Pass Snotel has picked up about 1.8" of water, all falling as snow at mid and upper elevations. On March 5th, forecasters visited the site of a remotely triggered (D3) avalanche on Kangaroo Ridge, which ran on a layer of facets buried in mid-February, just above the Jan 31st crust. 

Snowpack information is limited outside of the Highway 20 corridor and Harts Pass. Let us know what you find if you get out into the backcountry!

Regioni coperte