Bollettino valanghe

Selkirk Mountains

Idaho Panhandle Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The St. Regis & Silver Valley and Selkirks & Cabinets  forecast zones saw a bunch of new snow and wind over the weekend, which heightened the avalanche danger in high elevation areas, especially lee slopes where wind slabs are present. Yesterday we saw fracture lines from natural avalanches on NW facing slopes, near a NE facing ridgeline. Be sure to evaluate snow and terrain carfully. Human triggered avalanches are possible.

 

Problemi valanghivi

  • Wind Slabs

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

    Of all the places in the backcountry right now, it's safe to say lee (SE-E-NE) slopes above treeline are where you're most likely to trigger an avalanche. Wind slabs may be present on any aspect near and above treeline, mostly because of localized winds and terrain features, but most of the wind loading we witnessed was on SE-N-NE slopes.  In our data pit the wind slab was about 14'' thick. When we tested the snow, we did find low energy, moderate failures on facets that were sitting between the wind slab and the layer of snow below. The wind slab didn't show signs of propagation in tests yesterday, but that could change as the wind slab continues to stiffen.

    CT 12, Q2

    CT 8, Q2

    Wind slab over Hard slab

  • Persistent Slabs

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

    Testing snow columns in our data pit yesterday showed a weakness in the snowpack where the newer snow, which is a slab, interfaces with the old sugar snow (Basal facets) at the bottom. The interface between these layers was about 15'' up from the ground, which means if it did fail it would be a deep avalanche with lots of snow. It's a low frequency, high consequence kind of weak layer. This interface will become less of an issue as the snowpack gets deeper in the coming weeks and months. SNOTEL data shows that Lookout Pass has a settled base of 42'' and Bear mountain, in the Cabinets,  has 52'' of snow on the ground.

Avalanche Discussion

Yesterday Brian Hilland and I took the sleds into the Selkirk Mountains up to Hellroaring Ridge. We encountered about 24 more inches of snow than a week ago. The snow conditions were good getting up to the ridge. It was mostly 8-10’’ of new snow on top of a firm base. There was about 40 inches of snow on the ground in most places. Fun snowmobiling!

From Hellroaring Ridge we skied up the ridge to Flattop Mountain (6200’). We didn’t encounter much wind effect until we got up pretty high, 5200’ or so. We dug a data pit (see attached, in "Media") on a NW face at 6200’, just below the top. We chose this aspect because we felt like it may be the most problematic, so wanted to check it out.

As it turned out, we found enough uncertainty with the snowpack to change our ski decent. Instead of skiing the 38-degree Northeast face to return to the sleds, we popped over the ridge and descended the 27-degree Southeast side. It was a good decision. We found some glorious turns as we headed back to the sleds.

We're happy to see a relatively stronger snowpack to start the season, but snowpack is becoming more complex. As more snow comes, connectivity of slopes increases. Be sure to always know what the slope you’re on is connected to, considering the chance of remote triggers. Happy Holidays! Be safe!

 

 

Regioni coperte