Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

Dangerous avalanche conditions will develop as new snow and wind stress an already weak snowpack. You could trigger very large avalanches that break widely across terrain. Avoid traveling on or under slopes over 30 degrees at mid and upper elevations.

Problemi valanghivi

  • Persistent Slabs

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

    We expect the forecasted 4-6" of new snow and moderate winds to be enough to overload this weak snowpack structure. Triggering large persistent slab avalanches that break widely 2-4ft deep will be more likely as we put stress on the snowpack from additional snow. The most concerning slopes will be at mid and upper elevations, particularly in leeward terrain where the winds drift the snow deeper. However, you should treat any steep slope as suspect. Over the last week, there have been five close calls and one fatality involving this layer of weak-faceted snow over the Early February Crust. (Specific avalanche details in the discussion) Many of these observations indicate that the slope had already been skied/ridden once or multiple times before the avalanche occurred. While this reactivity is unusual for Washington, it is typical for this avalanche problem. 

    These avalanches are failing 2-4ft deep, propagating widely, and being remotely triggered from low-angle terrain below or adjacent to steep slopes. You might not receive signs of instability before the whole slope fails. It could be the 2nd, 3rd, or 8th person on the slope that triggers it. Avoid traveling on slopes over 30 degrees. This problem requires patience, conservative terrain selection, and maintaining wide margins between you and steep overhead terrain.

    (3/2/2024)

    You can still trigger very large avalanches like this example from last weekend.

    6600 ft on a NE aspect on Darland Mtn. 

    Photo: Katie Warren

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Increasing winds and a few inches of new snow could form fresh wind slabs near ridgelines, steep gullies, and the base of cliffs. We're most concerned about this problem at elevations above around 4000ft, with notably more snow over the Early February Crust. While these avalanches may start small, they may be likely to step down to deeper weak layers, become very large, and break widely.

    Look for actively blowing snow, cornice formations, and textured surfaces to identify likely areas for wind slabs. Avoid steep terrain where you identify stiff wind-transported snow.

    (2/28/2023)

    Look for pillow-like drifts and wind textured snow to help you identify slopes of concern. 

    Photo: Katie Warren

Avalanche Discussion

NWAC is devastated to report the death of one of our Avalanche Forecasters, Matt Primomo. Tragically, Matt passed away in a non-avalanche accident away from work on Thursday, March 7th. Matt has been a key member of the NWAC family since 2017. His life in the mountains touched so many people. We are absolutely heartbroken. Please join us as we mourn this immense loss with Matt’s family, friends, and community.

Discussion:Increasing precipitation and wind will quickly heighten avalanche concerns. We may see some rain at the very lowest elevations, making small wet loose avalanches or rollerballs possible. 

This pattern of persistent slab problems can be challenging for backcountry decision-making. It takes conservative terrain management and diligent patience. You're rolling the dice if you decide to ride in steep avalanche terrain. The structure is especially apparent in the eastern Cascades, where the snowpack is generally more shallow than at the crest. So, if you're venturing into these eastern zones, be prepared to take a step back in your typical terrain selection and understanding of the snowpack.

Summary of Recent Avalanche Incidents: On Thursday, snowbikers remotely triggered two very large avalanches in the Teanaway, and there was a close call with a skier who was caught and carried in an avalanche on the S aspect of Van Epps Peak. Earlier in the week, snowmobilers triggered large avalanches around the Blewett Pass area, and a skier was partially buried with minor injuries in an avalanche on a NW aspect of Jim Hill in the neighboring Stevens Pass zone. Last Saturday, there were two separate incidents near Darland Mountain. One avalanche resulted in a close call, but unfortunately, in the other, a snowmobiler was fully buried and did not survive.

You can add to the avalanche forecast. Submit your observation here.

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