Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Loose wet avalanches will become likely this afternoon on slopes that face the sun. Dry loose snow (sluff) is possible on north-facing terrain steeper than 35 degrees. Cornice failures have occurred in recent days and will continue throughout the mountains over the next two days. These massive blocks of snow are excellent triggers for avalanches.

Avalanche problems

  • Loose Wet

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

    Today will be the third consecutive day of clear skies and strong solar radiation in the mountains. New snow from earlier this week has been shedding for the past two days, especially in steep terrain that faces the sun. Expect more of the same today as temperatures are forecasted to be slightly warmer than yesterday. Wet loose slides will likely be within the upper 6-12" of the snowpack. The slides may not be large enough to bury a person, but will certainly be destructive, especially in steep, consequential terrain. Expect wet loose slides to start on east-facing terrain in the late morning to mid-day and wrap around the compass to the west in the afternoon. 

    Solar aspects will likely have a melt-freeze crust from the past two days. Watch for signs of the crust breaking down and becoming moist. If you notice signs of surface snow weakening and becoming damp, it's time to move to a shadier aspect. Pay attention to the terrain above you, especially if you're crossing underneath steep slopes later in the day.

    ADDITIONAL DISCUSSION: The other flavor of loose avalanches will be on tap for the northern part of the compass: dry loose (or sluffs). The upper 35 cm (15") of the snowpack is weakening with cold, clear nights. Expect to encounter small, dry loose avalanches in north-facing terrain steeper than 35 degrees. Be prepared to manage loose snow moving and avoid terrain traps.

    (3/17/2023)

    Loose wet avalanches in steep, sun-exposed terrain.

    Photo: Public-Peters

  • Cornices

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

    With the warming temperatures, you can expect to see cornices failing over the next day two days. Within the past 7 days, the forecast zone has seen two significant storms with heavy snow and strong winds. Cornices have grown to monstrous proportions along ridgelines. Cornices are the largest overhanging steep, N, NE, and E-facing terrain. However, there are plenty of large cornices along ridgelines that face other directions. As temperatures warm throughout the day, give yourself plenty of space around cornices. That means above and below. Cornices have a tendency to break back much farther than anticipated, so don't plan on walking up to the edge for photos. Pay attention to the terrain above you. If you're traveling underneath steep, overhanging cornices later in the day, give yourself plenty of space if these things let go. Imagine a refrigerator or small car tumbling down the slope at you at 60 MPH!

    Not only are cornices themselves a hazard, but they are an excellent trigger for avalanches. Two avalanches were observed yesterday as a result of cornice failure on steep, north-facing terrain around 7400' (pictured at right). If there are any pockets of lingering instability from the recent storm, these monsters would find them.

    (3/17/2023)

    These two avalanches were reported Friday (03/17), on steep, north-facing terrain around 7400'. Cornice failures triggered these two avalanches either Thursday or Friday.

    Photo: Public-Whitesell

Avalanche Discussion

Today's avalanche forecast is sponsored by Mile High Powersports of McCall. Thanks for supporting the Payette Avalanche Center.

Avalanche activity peaked earlier this week, sometime around Tuesday evening. Evidence of natural avalanches is widespread on multiple aspects above 7000'. Instabilities within the storm snow have settled and are stabilizing. SNOTEL sites have recorded  6-10" of settlement in the past three days! There could be some lingering pockets of instability, especially in wind-exposed terrain facing N, NE, or E above 7000'. 

We've received some excellent observations in recent days. Especially this one from the Warm Lake zone. This observation highlights the variability just outside of the advisory area. This avalanche was remotely-triggered and propagated into heavily wind-loaded terrain where the crown depth reached upwards of 8-10 feet. Remote triggering is a red flag that persistent weak layers are present. Do not assume this forecast applies to regions beyond this advisory area. Different mountain ranges experience different weather patterns and therefore develop different snowpacks. Luckily, this group of experienced skiers was practicing safe travel protocols and was aware of the possibility of a weaker snowpack. Stay attuned to differences throughout the region and make decisions with your group accordingly.