Bollettino valanghe

Continental

Valdez Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Backcountry users will find considerable avalanche hazard above 3000 feet today. Moderate to strong winds over the last 24 hours have redistributed recent storm snow into easily triggered wind slabs up to 2 feet deep in specific areas.   In lower elevations a moderate hazard exists due to the possibility of encountering wet loose avalanches or small pockets of windslab. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    Over the last 48 hours moderate to strong winds in upper elevations have produced sensitive windslabs throughout our forecast area. Numerous recent human-triggered windslab avalanches have been reported in the last 24-48 hours. Recent southerly winds from 20 to 30 mph with higher gusts have been actively creating sensitive soft slabs on specific leeward features. Winds shifting to the NNE in areas overnight have spread this hazard to additional slopes.  Yesterday reactive wind slabs were found on the leeward convex slopes, ridgetops, and in protected gullies throughout Thompson Pass. There is a high certainty that this activity will continue today. Expect to be able to trigger a small to large avalanche if you encounter windslab on slopes over 32 degrees today. 

    Windslab distribution will be variable today so you may find areas with more stable snow. Areas unaffected by wind will have a lower hazard. If you find good stability today be sure to reevaluate as you move to new terrain. 

    Additional snowfall and gusty Southeast winds are likely to contribute to the windslab hazard today. Watch for snow being transported by the wind on ridgetops and along unprotected shoulders through Thompson pass. Avoiding steep terrain on the leeward side of mountain features is recommended today.  

     

     

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Wet loose avalanches will be possible in lower elevations today. The Additional snow we are receiving may create a wet loose hazard at lower elevations if we see significant accumulations and warm temperatures. Small slides involving new snow may entrain old wet snow creating larger slides in areas. Expect solar warming to have little effect today. 

    Wet loose conditions are easy to identify.  Once more than a few inches of snow becomes moist-wet (you can easily form a snowball) then wet loose avalanches will become possible both human-triggered and natural on steep terrain.   Roller balls and snow snails are a good visual indicator that wet loose is currently an issue.  Plan your route to avoid exposure to steep low elevation slopes when the surface is not frozen.

    Avoid traveling on or below steep terrain where more than a few inches of moist snow exists.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–2

    Our ongoing persistent slab problem has been mostly unreactive but we are still keeping it on our list due to the high consequences of triggering this layer. Buried surface hoar 2-3 deep exists in certain areas above 3000 feet in our forecast zone. Over the last couple of weeks few large human-triggered avalanches have shown that this layer can be triggered in isolated areas. Areas where this hazard could be triggered include heavily loaded convex slopes, thin areas that propagate into a deeper slab or areas where a windslab avalanche might step down into deeper layers. 

    Persistent slab avalanches will be unlikely today but if triggered could have large consequences. A healthy curiosity regarding this layer is recommended especially if you are headed into new or infrequently traveled terrain. Use safe travel protocols to minimize exposure to this problem today. 

    Propagation Saw Test (PST) in the Tsaina valley 4200' that was reactive on 3/29 BSH. PST END 30/100 down 95 cm.  

    Photo: Gareth Brown

Avalanche Discussion

RECENT AVALANCHE ACTIVITY:  

Many human-triggered avalanches have been reported in the last 72 hours involving the most recent storm snow above 5000'.  These have been in the D1-2 range and have been 8-18" in depth.  Wider propagations have been reported in instances where the storm slab was stiffened by wind.

Last human triggered activity at 3/29 layer was reported on 3/2

DISCUSSION:

The most likely hazard today will be triggering a windslab avalanche up to 2 feet deep.  This hazard is likely to increase and expand its distribution to additional slopes with new snow and shifts in wind direction. 

Continued monitoring of the 3/29 BSH layer is prudent due to the high consequences of triggering a deep avalanche. We expect bonding to be gradually improving at this interface but additional snow loads could contribute to increased sensitivity.  There is a high amount of uncertainty about how this layer will be affected in the short term. Stay tuned and stay curious about what's going on under your feet.

Additional Concerns:

This is the time of year when cornices begin to fail.  You can significantly reduce your overall exposure in the mountains this time of year by avoiding traveling on top of or under cornices.

Glide cracks- Glide cracks are on the move at a snails pace and could release at any time. Avoid travel under these features. One small glide crack release was witnessed last week on a lower elevation solar aspect near port Valdez.

 

 

 

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