Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

4-10" of recent snowfall and S/SW winds have created wind slabs 6-12" thick. You're most likely to encounter wind slabs above 7000' around ridgelines. If the sun pops out, expect small, wet loose avalanches on south-facing slopes.

Today's avalanche forecast is sponsored by Mile High Powersports of McCall

Avalanche problems

  • Wind Slabs

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

    The mountains have received anywhere from 4-10" of snowfall within the past 48 hours. Yesterday, S/SW winds were blowing and drifting snow into fresh wind slabs. Wind slabs were found on windward as well as leeward slopes. You may encounter wind slabs 6-12" thick above 7000'. You're most likely to find sensitive wind slabs on N and NE aspects near wind-exposed areas like ridgelines. We've seen some atypical wind directions this past week so be suspect of wind slabs on multiple aspects above 7000'. 

    Local terrain features can significantly alter prevailing wind patterns. Be on the lookout for fresh wind slab development across multiple aspects today, even as you travel down from ridgetops. Gullies, rollovers, and other micro-terrain features can become wind-loaded farther down the slope. Watch for obvious signs of instability like shooting cracks. Pay attention to clues like drifts, pillows, and fresh cornices. If you feel dense snow overlying weaker, softer snow, you've found a wind slab.

  • Loose Wet

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

    The recent storm snow may see strong amounts of solar radiation today. If skies clear and the sun breaks out, expect to see loose avalanches. During the morning and on shaded aspects, these will be more of a dry loose character. Wet loose avalanches will be possible on any south-facing slope. Most folks know the drill: new snow will begin shedding off rocks, trees, and cliffs in steep terrain; as daytime heating increases and more of the upper snow becomes saturated, these wet loose slides could entrain more snow and run farther distances. There remains uncertainty with the weather forecast and there's a chance the mountains could stay cloudy with continued snow showers. If that happens, wet loose avalanches will be unlikely.

    Watch for pinwheels or rollberballs coming down the slope. These are a sign that the snow surface is becoming moist and unstable. Clues such as these are indicators that wet loose avalanches are becoming more likely. Pay attention to the terrain above you if wet loose avalanches begin to increase.

Avalanche Discussion

FEBRUARY CONDITIONS UPDATE

Late January we saw a significant rain event where rain levels rose up over 8000'. On the heels of the rain event, we experienced 4 days of near record warming. All of this warm, wet weather saturated most of the existing snowpack making an already dense slab of snow even denser. As temperatures cooled, the saturated snow formed a very thick crust complex that was buried on 02/01. The first 8 days of February the region experienced cool weather with consistent light snowfall. Stability and snow conditions improved significantly during the first 10 days of February. Five days of dry weather brought us to Valentine's Day. Before last week's storm, we noticed facets forming above and below the 02/01 crust complex. The mountains received 1-2' of snow last Wednesday-Friday. There was a brief natural avalanche cycled that ensued at the tail end of the storm. Three more days of dry weather with one 24-hour period with below average temperatures. Monday-Wednesday this week, the mountains picked up another 5-10" of snow with warmer than average temperatures. 

During the month of February, every avalanche problem listed in the forecast has been new snow related (loose snow, wind slab, storm slab). Up until yesterday, we have not experienced any propagation within snow pit tests during the month of February. Yesterday, we had an ECTP 20 & 23, 73 cm (30") down, just beneath the 02/01 crust complex. This pit was on a W aspect around 7700. Is this an outlier or a trend? We don't know yet, but solar aspects (or aspects on the margins such as E and W) could be harboring weak snow above and below the crust. Fortunately, the weather forecast should help heal this potential problem. If you're out in the mountains over the next few days, let us know what you're seeing by submitting an observation

Every observation submission gets entered into the FPAC monthly raffle. If you submit an observation, you could win some great prizes courtesy of the FPAC. We've only had two submissions from motorized users this season. (The odds are stacked in your favor to win a prize for the motorized raffle). Tell us what you're seeing when you're out riding in the mountains. Observations (such as these recent ones) can greatly improve information for avalanche forecasts.