Avalanche forecast

East Cabinet Mountains

Idaho Panhandle Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Avalanche danger on the Kootenai will steadily rise to Considerable on Tuesday as fresh snow and winds create reactive slabs in steep terrain. Triggering a slab in terrain steeper than 35 degrees at tree line and above will become likely by this afternoon with north and east aspects below ridgeline being the most dangerous locations. Today will be a great day to enjoy the fresh powder, you can do it safely by avoiding steep alpine terrain and playing on lower angle slopes sheltered by timber.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5

    The East and West Cabinets are predicted to pick up and additional 10-12" of snow Tuesday that will be accompanied by gusty winds out of the southwest. This will cause slabs to build through the day that will remain reactive through Wednesday. With winds predicted to be sustained in the upper teens to low 20's, we will likely see extensive loading on north and east aspects at upper elevations and directly below ridgelines. The new snow will have the most potential to produce avalanches directly below ridgelines on northerly aspects where it may be resting on buried surface hoar and has been affected by the wind. Pay attention to changes in the surface of the snowpack today as this storm progresses, watch for cracking in the snowpack surface as this will be your clue to increasing avalanche danger today.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3.5

    Two issues exist here that are worth noting. Last week we found surface hoar developing under the clear and cool conditions that has survived on north facing and shaded terrain. This surface hoar was buried on Sunday and may provide a reactive surface today as we add another layer of snow. On Monday we observed that the buried surface hoar was highly variable in both its distribution and reactivity, this makes for a scenario that is hard to predict as one travels through the mountains. The best course of action is to assume it is a problem until you dig into the snow to prove otherwise. The second issue of note is the February 3rd rain crust layer, now found deep in the snowpack. The likelihood of triggering an avalanche on this layer is currently low and has the most potential in the Purcell Range where the snowpack is thinner and more likely to have developed weak and sugary snow above this crust. My biggest concern with this layer is the warm and sunny weather predicted by the weekend. This crust layer may become the reactive bed surface for a large avalanche cycle as we see our first warm and sunny days this weekend.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    It is currently raining outside and predicted to continue doing so up to 4,000' through Tuesday. Anticipate the potential for small wet avalanches to become an issue in steep terrain below tree line as the surface of the snowpack becomes wet and slushy. Paying attention to this issue in areas where a small avalanche can sweep you through trees, over cliffs and into creek beds will be worthy of your attention at elevations below 5,000' today.

Avalanche Discussion

Monday's tour into the East Cabinets revealed a mostly stable snowpack that showed few concerns in stability tests as the snowfall from the first week of March has now settled and bonded well. We did observe instabilities near the snowpack surface on north and east aspects near ridgeline where Sunday's fresh snow was packed into cohesive slabs that were reactive under foot and produced shooting cracks. As one dropped into sheltered terrain away from the ridgelines these instabilities dissipated. 

Moving forward we have some dynamic weather this week that will keep us on our toes. The storm that moved into the area over night is going to change yesterday's stable conditions and create the potential for slab avalanches to occur in steep terrain through Wednesday. The second big change will be our first really warm and sunny spring days of the year predicted to occur later in the week. The first big warm-up of the season always produces avalanches so keep that in the forefront of your mind if you are planning to get out this coming weekend.

Regions covered