Avalanche forecast

Mount Shasta

Mount Shasta Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Heightened avalanche conditions will continue today in above treeline terrain, due to continued warming. Instability will reach its peak in the late afternoon, with wet loose avalanches and cornice collapse possible on W-S-E aspects. Reduce exposure to these problems by getting off solar slopes before significant warming occurs.

Avalanche problems

  • Loose Wet

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

    Calm winds, sunny skies, and warm temperatures will continue today. Last night provided a poor refreeze of the upper mountain, with some areas not freezing at all. Upper mountain terrain will start the day off warm, quickly destabilizing as the warm temperatures penetrate deeper into the snowpack. Wet loose avalanches are possible on W-S-E aspects at all elevations, with particular emphasis on terrain near and above treeline. These slides have potential to become large, capable of burying you, or carrying you over consequential terrain. Look for early signs of rising instability such as roller balls, pinwheels, sticky snow, failing test slopes, and deep boot penetration.

    (12/30/2023)

    D1 wet loose avalanche. An obvious sign of rising instability.

    Photo: Samuel Clairmont

  • Cornices

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

    Throughout the course of the winter, large cornices have developed across the forecast area. As temperatures continue to climb, with poor refreezes overnight, these cornices will begin to weaken. If they fail, these cornices also have the potential to trigger a subsequent wet loose avalanche below. Some of these cornices are the size of small cars, certainly capable of hurting or killing someone if they fail. Best bet is to stay off of them over the next 24 hours. Give these cornices a wide berth, as they notoriously pull back further than expected.

    (3/25/2023)

    An older photo of large cornices at Cliff Lake. March 2023.

    Photo: Samuel Clairmont

Avalanche Discussion

Today, high pressure and its subsequent warming temperatures will reach their peak for the week. This morning, Gray Butte is recording 39 degrees F at 5am, which is a few degrees warmer than yesterday morning. It's taken a few days for upper elevation terrain to soften significantly from the warming conditions, but today will likely be enough to finally loosen things up, and elevate the instability. Northerly, shaded aspects continue to be cold and firm, seeing very little effect from the warm weather. If you're planning to get out into the backcountry, plan to get off solar aspects before the slopes warm to an unstable level, which won't take long. If you time it right, there is some good early season corn skiing to be had. Lower elevation slopes will become softer much quicker than above treeline terrain.

Yesterday, forecasters traveled up to Helen Lake where the warming conditions showed little for instability. No obvious signs of a weakening snowpack or avalanche activity were observed. Most cliff bands are still holding onto its rime ice, meaning ice fall will continue to happen today. By midafternoon, boot penetration was around 3–4 inches, softening very slowly for the amount of warming that's happening. Many surfaces are still very wind effected up high, with variable texture and consistency. While at Lake Helen, two climbers slipped and fell below The Heart, sliding ~800 feet down slope before stopping in flatter terrain. Both climbers were uninjured, but this is a good reminder that upper mountain slopes are still very firm and could be difficult to self arrest.

Lower elevation terrain has seen warm conditions for the last five days, and has experienced a moderate freeze-thaw cycle. Boot penetration in this terrain has reached around 12 inches depth. Runnels have formed on solar aspects below treeline, indicating free flowing water within the snowpack.

Tomorrow, high pressure will begin to break down, with temperatures beginning to drop. Tomorrow is looking to be similar to Sunday's weather, with building clouds later in the afternoon. Later in the week, precipitation will return.

The road to Castle Lake is closed. Siskiyou County is working to get it open as soon as possible.

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