Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The avalanche danger will rise to MODERATEas sustained sunshine melts snow surfaces throughout the day. Small loose snow avalanches will become easier to trigger throughout the day on steep slopes facing the sun where the snow surface feels moist. These can start small but gain speed and size as they move downhill. An early start and early exit is today's best strategy. Triggering large avalanches that fail on deeper weak layers is most likely in very steep, rocky, alpine terrain.

Avalanche problems

  • Loose Wet

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

    Unimpeded, sustained sunshine has been soaked our mountains all day yesterday for the first time since recent storms, and will continue today. This morning starts out warmer than yesterday, with a weaker freeze in most locations last night. The fresh snow from the past week will moisten as the sun rises higher in the sky. This newer snow sits on top of crusts from over a week ago. As surface snow melts and water percolates down to these crusts, it will become increasingly easy to trigger loose avalanches in this wet snow. These are most likely on steep slopes that face the sun, will start out small, and can gain speed and size as they run downhill.

    Luckily this problem is easy to identify and manage through timing. Starting early and planning for an earlier exit will allow you to be off of steep slopes before this problem is at its worst. If you're encountering wet snow on a steep slope and your skis are sinking farther into it than earlier, it's likely time to get off the slope. These will run naturally during the heat of the day. 

    ADDITIONAL DISCUSSION - CORNICES: As the day warms us, be aware of old large cornices lingering both overhead and on ridgelines you may be traveling on. The chances of one of these failing will increase throughout the day 

    (3/30/2024) Wet loose slides 

Avalanche Discussion

Walking out into the mountains there are three considerations you should have today in the Banner Summit zone. 

WARM & WET: The mountains saw their first dose of sunshine since recent storms yesterday. Solar input and even warmer temperatures continue into the day today with a weaker freeze overnight and warmer temperatures this morning. This will melt the snow surface throughout the day, increasing the likelihood of wet loose avalanches as the day goes on. These will be most likely on steep slopes that receive direct sunshine, and below rocky outcroppings and cliffs. While these will likely be small, expect the wet snow to carry enough force to knock you off your feet in consequential terrain. Timing and situational awareness will be key to managing this problem. Pick a turn around time and stick to it. 

WINDED: Although not registered on our mid-elevation weather stations, a moderate to strong wind event took place in the Boulders two nights ago into the morning yesterday. This built new wind slabs in the alpine that proved to be reactive to human triggering— one of which caught, carried, and partially buried a snowboarder.  Although the Banner Summit zone has seen less wind in recent days, old wind features and cornices linger in the Banner zone. Keep this type of issue in mind as you head out today. While these slabs will be relatively small, considering them in your travel plans will be essential to a safe day in the mountains. You are most likely to run into this problem near ridgelines, in mid-slope features like gullies, and on the aprons of large alpine bowls. Visual clues like wind scouring on windward slopes, texturing on leeward slopes, and dune-like features will be your best bet to identifying where this problem lives. 

WEIRD: While the chance of triggering an avalanche on deeper persistent weak layers is unlikely, it is not impossible. Triggering one of these is most likely in very steep (>45 degree), rocky, alpine terrain. Know that while the chances of triggering one of these slides is low, that your chance of surviving one of these beasts is equally low.  

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