Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The danger hasn't changed and neither should your terrain selection. Continue to tip-toe around terrain connected to steep wind-loaded slopes including those with large overhanging cornices.  If you experience whumpfs or collapses in lower angle terrain, make sure to avoid nearby steep slopes at any elevation. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    The potential for surprising and dangerous persistent slab avalanches should continue to shape your travel decisions.  You may trigger these avalanches on steep slopes as well as unusual places far away from typical start zones.  Deeper and more consequential slabs are more likely to be found on lee slopes near the Cascade crest and near and above treeline where westerly winds have drifted snow over the last week.  Minimize your exposure to large avalanche paths and look for safe locations to stop or regroup.  Choose simpler and less wind-loaded terrain until conditions change. 

    "Red flag" signs of the danger include whumpfing collapses, cracks shooting through the snow, and tests that propagate or fail suddenly.  You can dig down and find the culprit, the late-January weak layer, 1.5-2 feet below the surface.  In many areas, this layer is a combination of weak sugar-like facets between two crusts.  Below 5,600ft you may find buried surface hoar at this interface. We have good information about the problem near Washington Pass, Rainy Pass and Hart's Pass. Further east in the zone, a similar weak upper snowpack structure exists but the slabs resting above the persistent weak layer are likely thinner.  See or hear something?  Let us know.  

    (2/4/2022)

    A party remotely triggered avalanche (R4-D1.5) from 600 feet away in the Hart's Pass area. This avalanche sympathetically triggered another small slide nearby. East, 6,800ft.

    Photo: Josh Cole

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Following a mild overnight with above freezing temperatures forecast at all elevations, be on the lookout for small loose wet avalanches Thursday.  A cooling trend expected in the afternoon will lower the wet loose potential, especially on shady slopes.  Moderate to strong winds may also lower the likelihood of loose wet avalanches on wind-exposed slopes.  Small loose wet avalanches are most likely on steep sunny aspects and in areas sheltered from stronger winds. 

    If you see pinwheels or rollerballs, the snow feels wet and heavy,  or evidence of new loose we avalanches, change aspects or move to lower angle terrain.  Be mindful of overhead hazards and terrain traps that can increase the consequences of being caught in even a small avalanche.

    Limit time below slopes with large overhanging cornices (see photo below) and give them a wide berth if traveling along ridgelines.  While falling blocks of hard snow are a hazard in their own right,  they may also trigger large avalanches on the slopes below. 

    (1/21/2022)

    Loose wet avalanches (likely from Jan 20th) on steep sun-exposed slopes near the top of Washington Pass.

    Photo: Drew Lovell

Avalanche Discussion

Snow surfaces were moistened on all aspects Wednesday as temperatures rose above freezing at all elevations and clouds increased.  While snow surfaces have changed over the last week, snowpack test results continue to show sudden results on northerly aspects on the late January crust/persistent weak layer throughout the Highway 20 corridor including in the Hairpin Valley and on Kangaroo Ridge.  Widespread whumpfing and one large rolling collapse were noted by professionals in lower angle terrain near Washington Pass Tuesday.  NWAC forecasters on Monday found a touchy snowpack in the Silverstar area at low, mid, and upper elevations.  On Sunday, guides near Hart's Pass reported numerous natural persistent slab avalanches on leeward sides of ridges, large collapses, (traveling up to 600ft). 

Notable avalanche observations in the last week:  On Saturday 2/5, a party of backcountry travelers triggered a 3-foot deep slab avalanche near Maple Pass on an east aspect at 6,600ft. Three of the four riders were involved with the avalanche and one was carried 400 vertical feet, but unharmed. See the photo below.  Natural and human-triggered wind slabs were reported last weekend.  On Friday 2/4, observers remotely triggered a slab avalanche (size R4-D1.5) from approximately 600ft away on an east aspect near 6,800ft in the Hart's Pass areas. This slide triggered another (sympathetic) small slab avalanche. 

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