Bollettino valanghe

Island Park

Gallatin NF Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 8 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Despite recent warm weather, weak faceted snow near the ground remains a concern and keeps alive the persistent slab avalanche problem. Snowfall and strong winds today will make that problem more sensitive. Today’s snow and wind will also form fresh wind slabs that will be easy to trigger. Seek out slopes at lower elevations sheltered from the wind. 

Problemi valanghivi

  • Persistent Slabs

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

    Wind loading will make this problem more likely today.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    Winds should be drifting snow at all elevations today.

Avalanche Discussion

In all areas today, strong winds will drift the new snow and form wind slabs that will easily avalanche. Areas with more snow will have larger wind slabs. With such strong winds, these wind slabs will be all over the place and not just at ridgetops.

Also in all areas today, persistent slab avalanches remain the most dangerous problem. The extra weight of wind blown snow will increase the  likelihood of triggering one of these large avalanches breaking on old, faceted snow from this fall. 

How has recent very warm weather affected things? 

  • At mid and upper elevations, weak, faceted snow causing the persistent slab problem was insulated from warm temps and remains weak. See Dave's ob from Beehive and Alex's ob from Mt. Blackmore. 
  • Low elevations have lost a lot of snow and generally didn’t have the old, faceted snow from this fall (except near Cooke City where elevations area generally higher)
  • On many sunny slopes, the surface snow became wet and now has an ice crust.
  • On many shady slopes, or ones receiving partial sunshine, the surface snow actually became loose and faceted because of the flip flopping warm days, and clear nights.

What to do and where to travel? Today, adopt a mindset of stepping back as the danger will be rising. Be prepared to enter the mountains on high alert in the coming week or two with heavy snowfall and strong winds possible through the rest of December.

Low elevation slopes sheltered from the wind and lacking old faceted snow from this fall will be an option, but finding slopes sheltered from the wind will be a challenge. Slopes less than 30 degrees in steepness (and NOT underneath steeper slopes) are another great option because they’re not steep enough to slide. 

With strong winds and snow falling today, the danger will be rising to CONSIDERABLE with wind slabs easy to trigger and the likelihood of triggering larger persistent slab avalanches increasing on wind loaded slopes.

Regioni coperte