Bollettino valanghe

Northern Wallowas

Wallowa Avalanche Center
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Pericolo valanghe

Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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In sintesi

A significant storm has impacted our area mountains. Upper elevations in the Southern Wallowas received 12-18" of storm snow in the last 24 hours with up to 6" more expected today. Expect to find unstable storm slabs a foot deep or more on any slope > 30 degrees. Winter recreationists are encouraged to avoid avalanche terrain and stay off and out from under slopes greater than 30 degrees.

Today's forecast is sponsored by onX Backcountry

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Problemi valanghivi

  • Storm Slabs

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

    The 12-18" of new snow that has fallen in the last 24 hours will not bond well to the underlying snow surface. We have a density inversion in the upper snowpack with the denser new snow falling on lighter density snow from earlier in the week.  This is creating unstable conditions. Storm slabs of 12-18" in thickness will be easily triggered by the weight of a rider. Winter recreationists should avoid avalanche terrain today. Stay off and out from underneath any slope > 30 degrees.

  • Wind Slabs

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

    Overnight the wind at 7500' blew out of the SE at 15-25mph with gusts in the 30's. The 12-18" of new snow will be easily transported by the wind. Expect to find reactive 1-3' wind slabs on steep (>35 degree) on W-N-E aspects near ridgeline and on cross-loaded terrain features mid-slope. Look for smooth rounded pillows below ridgeline and on the leeward side of ribs and gully features mid-slope. It is best for the next few days to avoid steep alpine terrain where reactive wind slabs may lurk. Triggering an avalanche will be catastrophic to life and limb.

    Check out the WAC forecaster report from the Northern Elkhorns yesterday.

    (3/9/2023)

    This natural wind slab avalanche likely released early Thursday morning. The 2" of new snow, along with light density snow from storms earlier in the week, was being easily transported by moderate southerly winds onto north-facing terrain.

    Photo: M. Hatch

Avalanche Discussion

Protected and Sheltered Slopes Below Treeline

The snow quality on more protected and sheltered terrain is incredible right now.  Unstable conditions warrant staying out of avalanche terrain and sticking to slopes >30 degrees. Below treeline is the place to find the best snow quality and stay out from underneath steep slopes. There really isn't a good reason to go above treeline - you'll be punished by the wind and greatly increase your exposure to unstable conditions.

Storm Slab

The Southern Wallowas received 12" of new snow and 1" water. I expect upper elevations received up to 18" of new snow in the last 24 hours. Snow does not respond well to rapid change. Getting feet of new snow in such a short period of time will create unstable conditions. Recreationists are encouraged to avoid and stay out from underneath slopes >30 degrees where snow totals surpass 12" or more in a 24-hour period.  Expect the avalanche danger to remain elevated through the weekend. Conservative route selection and travel protocols are a must.

Cornice Fall

In my travels into the alpine in the Elkhorns yesterday, I found significant build-up of cornices at and near ridgeline. As this week marks the seven year anniversary of the death of our dear friend Kip Rand from a cornice fall on Chief Joseph Mountain, it is important to remember to give overhanging cornices wide berth. Make sure you are on terra firma - look for trees and exposed rocks along with staying on the windward side of ridges.

 

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