Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Wind slab avalanches 1-2 feet thick are likely above 7000' in wind-exposed terrain. Wind slabs could spell double trouble by triggering an avalanche on persistent weak layers over 2 feet deep. Persistent slab avalanches are possible across multiple aspects and elevations. 

Avalanche problems

  • Wind Slabs

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

    6-10" of recent snowfall along with strong SW winds were forming wind slabs above 7000' yesterday afternoon. The winds look to have decreased overnight, but you can expect to find fresh wind slabs above 7000' in wind-exposed terrain. Before this storm there was snow available for transport so wind slabs could be anywhere from 1-2 feet thick. Watch for signs like shooting cracks from your skis or sled as you climb in elevation. Pay attention to clues that the wind was at work like scoured snow surfaces, drifts, or pillows. Wind slabs will be thickest on east-facing terrain near and below ridgelines. Local terrain features can alter prevailing wind patterns and cause wind loading across multiple aspects. These wind slabs have built upon persistent weak layers in the upper snowpack and may trigger a larger avalanche (see problem #2).

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2

    2-4 feet of new snow last week fell on a variety of buried weak layers. This recent snow formed a slab about 2 feet thick overlying persistent weak layers that were buried in early January. On shaded slopes, a layer of buried surface hoar and near surface facets was very reactive during last week's storm cycle. On solar aspects and lower elevation slopes, facets beneath a melt freeze crust was equally reactive during the storm. Both of these weak layers are about 2 feet down and are slowly strengthening. Unfortunately, this persistent slab problem is widespread across all aspects and elevations. Persistent slabs will be most reactive today where the wind has built fresh wind slabs (see problem #1).

    (1/17/2024) 6990', S aspect, HS 105 cm (3.5ft.). Layer of concern was facets beneath a melt freeze crust. Photo: Kevin Studley

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–2.5

    Triggering an avalanche on deep persistent weak layers from November is unlikely. The poor snowpack structure still raises alarm, especially with the continued weight being added to the snowpack. You are most likely to trigger a large avalanche within old snow near the ground in steep, rocky terrain where the snowpack is shallow. 

Avalanche Discussion

2-4 feet of snow fell last week on a variety of weak layers. Most of this snow settled into about a 2 foot thick slab overlying persistent weak layers. Natural avalanche activity spiked several times during last week's storm cycles. The most recent avalanche activity occurred Friday. Looking ahead, southwest flow aloft will bring warm, moist air into the region with continued precipitation. Although storm totals aren't forecasted to be significant, heavy wet snow can pack a punch and add a lot of weight to the snowpack. Unlike all of us snowlovers, the weight is what's important to a snowpack, not the depth of new snow. Rain/snow levels are forecasted to rise to around 6500' between Friday and Saturday.

Join the Friends of the Payette Avalanche Center (FPAC), this Friday (19th) at Salmon River Brew Pub for a pint night. From 530-730PM, $1 from every beer purchased goes to the FPAC which directly supports the Payette Avalanche Center.

Get your name in the hat to win some gear in our FPAC monthly drawing when you submit an observation. Submitting an observation improves your skills, informs other users, and benefits avalanche forecasts. Simple photos highlighting conditions are very helpful.

Did you know there several avalanche classes this month specifically for motorized users? Check out our classes and events page to learn more.