Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
3 · Erheblich
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Kernpunkte

Large and surprising avalanches occurred in the Baker backcountry on Monday, plus we're getting more snow overnight and through Tuesday. Natural activity will continue, and dangerous human-triggered avalanches are very likely. Other areas in the zone may not be quite as reactive. Avoid all avalanche terrain, which includes steep spots where avalanches start, plus lower angle and flat terrain beneath steep slopes. 

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1.5–2.5

    You are more likely to trigger an avalanche on wind-loaded slopes, but consider all steep slopes suspect. You can expect 2-4+ feet of snow from the storm that began last Thursday, and the brunt of the storm is Monday night. Avalanches may break beneath the old snow layer on a persistent weak layer (see Avalanche Problem 2), or they may break within the new snow layer.  Given all the uncertainty and the large amount of snow that we're getting, avoid all steep slopes and the terrain beneath them as well.  Avalanche danger is expected to increase as you gain elevation. Avoid all steep slopes and the terrain beneath steep slopes where avalanches run and then stop. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    2–2.5

    On Monday, backcountry users and the Mt Baker Ski Patrol were surprised by natural, human-triggered, and explosive-triggered avalanches. The snowpack was touchy and avalanches broke in surprising ways and in unusual places. Most, if not all, of these avalanches likely failed on a layer of surface hoar buried beneath the storm snow which began falling on Friday, 3/8.  Many crowns were estimated at 3 feet deep, and most avalanches were large, D2. One backcountry user reported, "Today was one of those days where the vibe was 'nope' on anything out of bounds."  You can read an observation from the day HERE. 

    With another 1-2ft of snow added by Tuesday, avalanches will become larger and more destructive. Natural avalanche activity is expected to continue, and human-triggered avalanches are very likely. Triggering or getting caught in one of these avalanches will most likely kill you. Several remotely triggered avalanches were reported, so even if you aren't in avalanche terrain, a whumph beneath you could communicate through the snowpack to a distant steep slope, which may then avalanche.

    Avoid all avalanche terrain on Tuesday. This means all steep areas, lower angle terrain, and even flats beneath steep start zones. Avalanches could slide on 30° or even shallower slopes. I once traversed across a small 25° slope, and two others followed in my exact tracks, and the 4th, heavier person in the same tracks triggered an avalanche that failed on surface hoar on that tiny slope. We were lucky it was completely inconsequential. 

    We know this layer exists in the Baker backcountry, but it may not be as prevalent in other areas throughout the zone. In general, we mostly suspect it exists on mid-elevation shaded slopes where the surface hoar wasn't destroyed by the sun and where the wind didn't blow it away. This doesn't mean you can assume it doesn't exist elsewhere, either in the zone or on other slopes - it may be in smaller pockets and less widespread, or possibly a bit more broken down, requiring a bigger trigger (like a human) for the avalanche to occur. 

    (3/11/2024) Large and unusual natural avalanche activity in the Baker backcountry on Monday. You can expect larger ones to occur naturally on Tuesday. 

Avalanche Discussion

NWAC will be closed on Tuesday, March 12th, as we gather and grieve following the death of one of our forecasters, Matt Primomo. We will not issue regular avalanche or mountain weather forecasts on Tuesday. We will return to normal operations on Wednesday, March 13th. We appreciate the community's understanding and support during this time.

Outlook for Wednesday:  Avalanche danger is expected to slowly improve on Wednesday as the storm winds down. Less natural avalanche activity is expected, but human-triggered avalanches will still be likely. Persistent slab avalanche problems don't usually go away overnight, so large, scary avalanches are still expected. The sun may pop out and moisten southerly surfaces, and small amounts of wet loose avalanche activity could result. 

Forecast discussion:

Forecasts are showing over an inch of water overnight, which could equate to over a foot of snow. Over half an inch of water, around 6 inches of snow, is expected to fall during the day. Near the bottom of the lower elevation band, we'll probably be getting rain and snow will be moist. Small wet loose avalanches may occur. The other avalanche problems noted will be less likely in these areas. 

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