Lawinenlagebericht

Lawinenlagebericht

Payette Avalanche Center
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Lawinengefahr

Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
Veraltet — dieser Lagebericht ist 6 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

The Avalanche danger is Considerable today above 7,000 feet.  Natural avalanches are possible on Steep Solar aspects, and Human triggered avalanches are possible, especially in wind loaded terrain where wind slabs may be sensitive and have formed over persistent weak layers. Watch for cracks shooting out from your skis or sled on or near ridgelines.  Shallow, dry snow avalanches running on the crust will be likely on slopes over 30 degrees.  Avoid steep terrain taking on direct Sun, and take the time to dig into the snowpack before you commit to any consequential terrain.

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Our latest snow has seen some sun, but the clouds on Friday filtered it's effect on the surface, heating up some solar aspects, and producing wet loose natural avalanches. Today, under full effect, solar aspects from East in the Morning through the South and West into the afternoon should be shedding some snow in the form of wet-loose natural avalanches. You have the potential to get some snow moving on steep slopes in the sun. Avoid Solar aspects that are getting a lot of heat, especially in the afternoon.

    SE aspects near Squaw Point on Friday 1/23/2021 picking up Heat from the Sun and producing wet-loose natural avalanches in Thursday's new snow

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–3

    Multiple weak layers exist within the upper 2-3 feet of the snowpack.  These layers are reactive in our pit tests and relatively widespread on wind-protected slopes.  The deeper of the two most obvious layers is is the layer that produced a widespread avalanche cycle last week.  While the snow surface seems firm and unlikely to produce additional avalanches in many places, human triggered avalanches should be expected on slopes that did not experience natural avalanches during the storm cycle.   Wind loading over the last week has allowed weak layers to become buried much deeper in some areas and created hard, old, wind slabs resting on weak layers below. Variability from slope to slope is common right now as well. In some areas, the layer of near-surface facets and surface hoar has been preserved very well while on similar slopes nearby, environmental factors left less of these crystal types intact.  Safe travel and terrain selection is cheap insurance right now.

    1/21/21-Extended column test- Full block propagation 25cm down(ECTPH24SC). Deeper layers were also active in compression tests. These are all of the high-pressure snow surfaces we have had over the last 3 weeks.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Wind has been a common theme throughout the last few weeks.  Even the most protected high elevation slopes have been buffeted.  Wind slabs are fairly widespread as a result and may vary from relatively soft to very firm and supportable to the weight of a skier.  Older, hard wind slabs may be buried deeper in the snowpack and resting on buried weak layers consisting of buried surface hoar and near-surface facets.  These weak layers will allow even shallow avalanches to propagate over large slopes and across multiple terrain features and could have the ability to step down into deeper buried weak layers.  We have seen this repeatedly over the last few weeks.  Many of last week's avalanches occurred in deposition zones that were well below ridgelines where the weak layers are still preserved.  High winds will load slopes in unusual ways.  Your best bet is to watch for visual clues of wind effect and pay attention to the density of the snow surface as you travel.  

     

    Wind Effect on the snow surface...looking at a SE Slope on Squaw Point on Frday

Avalanche Discussion

The snowpack is a mixed bag right now.  There are multiple overlapping problems within the snowpack that are blurring the size and boundaries between problem layers. Big lines are starting to fill in and ski conditions are improving. Now is definitely not the time to get lured into big terrain.  Local guides and forecasters are giving the snowpack a low confidence rating and avoiding steeper terrain.  With a few inches of new snow falling over the next few days, new weak layers will start to get buried.  Choose your terrain wisely and take the time to dig in and see what's going on in the snowpack before you cross the line into more committing terrain.

Deep In our snowpack, Low Probability High Consequence: Almost all aspects have the common factor of very weak, loose, faceted snow in the lower snowpack that was buried around December 14th.  These deep layers are getting hard to trigger in most areas but seem to be more easily triggered in the mountains to the south of McCall.   Avalanches triggered in these deep layers would likely be unsurvivable based on the size and density of the slab above them, continue to practice safe travel protocols in and around terrain steeper than 30 degrees.

Our observations page is growing, but we are still working out some bugs.  If you are submitting an observation and are having trouble, please send us a description of the problem.  You can email your observations to us as well.  These help the forecast team form a clearer picture across the forecast area. We will be continuing to improve the observation form to make your submissions even easier over the next few weeks. Photos of recent avalanches are also very helpful to the forecasters with a short description of aspect, elevation, and relative location.

Also, Please be mindful of other users, and where you are at. There are closures for motorized travel in and around the local ski areas, Granite Mtn, and other areas throughout our region.

***Check out the Winter Travel Map to find out where you can shred on your sled.