Lawinenlagebericht

Bitterroot

West Central Montana Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
3 · Erheblich
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Kernpunkte

An avalanche warning has been issued for the West Central Montana forecast area. The avalanche hazard is currently high in the Rattlesnake.  In the Seeley and Bitterroot zones, the hazard will rise to high throughout the day today with continued snowfall and wind. Human-triggered and natural avalanches over 2 feet deep are very likely at middle and upper elevations. Avoid slopes over 30º and leave wide margins underneath avalanche terrain.  Travel in avalanche terrain is not recommended.

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1–2.5

    In the Rattlesnake, the Stuart SNOTEL reports 1.8" of snow water equivalent (SWE) or over 18" of snowfall in the past 24hrs. The  Seeley and Bitterroot zones have received up to 1" SWE and are on track for heavy snowfall today. Another .75-1.5" SWE is expected through Saturday morning. Winds will be moderate to strong out of the west today and switch to northeast tonight. Yesterday, riders triggered slabs over 12" in the Seeley lake zone. Today, slabs will be over two feet thick at middle and upper elevations. Storm slabs will develop at lower elevations today as temperatures drop and snow accumulates. Wind-loaded slopes will harbor touchier and deeper slabs. Human-triggered avalanches are certain, and natural avalanches are likely. Avoid slopes over 30º, and stay away from convexities. Stay off of and well away from the base of avalanche slopes and paths. 

  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1–2.5

    In the Southern Bitterroot, facets can still be found at the base of the snowpack on upper elevation north aspects. This area has a shallower snowpack than the rest of the forecast area, and as a result, the basal facets are not healing as quickly. There have been no recent avalanches on the basal facets, but the structure is too poor to trust. You are unlikely to trigger this layer, but it could happen with just the right shallow trigger spot or a larger impact like a sledder trenching while high marking. The added load of today's storm may be enough to reactivate this layer in isolated areas. Avoid slopes over 30º. 

Avalanche Discussion

We are issuing an additional forecast today due to the development of very dangerous avalanche conditions. A significant storm is bringing heavy snowfall and strong winds to the region. The Rattlesnake and Seeley Lake zones are favored for the highest totals of upwards of 3 inches of SWE by Saturday morning. The central and northern Bitteroots are forecast to receive another 1-2 feet of snow by tomorrow morning. The Southern Bitterroot is forecast to receive the least amount of snow at 1-1.5 feet, but the avalanche hazard will rise there as well.

Human-triggered avalanches large enough to bury you are certain today. Natural avalanches are likely.  Don't fall prey to powder fever. Stick to low angle slopes under 30º, and give the fresh snow time to stabilize.  The storm related instabilities should settle out in a few days. Very cold temperatures after the storm will preserve the powder.  The excellent riding conditions will remain, but the avalanche hazard should decrease. Wait until then to step out to steeper slopes. 

Ski and ride safe. 

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