Lawinenlagebericht

Bitterroot

West Central Montana Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
4 · Gross
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Kernpunkte

The avalanche warning has been extended through today. Wet snow, rain, and temperatures above freezing have created very dangerous avalanche conditions. The hazard will continue to rise today with ongoing precipitation. Very large and destructive natural and human triggered avalanches are likely today. Traveling in or under avalanche terrain is not recommended. 

Lawinenprobleme

  • Wet Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–4

    Rain on snow, wet new snow, and freezing levels rising well above 7000' have saturated the snowpack. Temperatures were in the mid 40s in many locations yesterday and last night and have been above freezing for the last 72 hours. Significant rain up to 6500 ft is forecasted for today. The likelihood of very large wet slab avalanches at middle and lower elevations will continue to rise until temperatures begin to cool off tonight. Wet avalanches are unpredictable, can release without warning, run long distances, and are very destructive. Travel in avalanche terrain is not recommended. Do not travel through or under avalanche paths. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–4

    Multiple persistent weak layers throughout the snowpack and forecast area have been loaded by new precipitation and weakened by rapidly rising temperatures. Another .75 to 1.25 inches of precipitation today into tomorrow will overload the buried weak layers. Very large natural and human triggered avalanches, up to 5 feet deep and failing at ground, are likely. Avalanches could be triggered remotely from above, below, or the sides. Traveling in or under avalanche terrain is not recommended. 

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    8-15” of new snow and strong southwesterly winds are forecasted for upper elevations through tomorrow. Expect sensitive wind slabs on ridges and exposed terrain, especially on easterly aspects. Wind slabs often appear smooth and rounded. Smaller avalanches could step down and release much larger, full depth avalanches. Avoid slopes steeper than 30 degrees to manage the hazard today. 

Avalanche Discussion

It’s been a wild week of weather, and it’s not stopping today. A significant avalanche cycle is likely. Currently, the totals stand at 2 - 4.5 inches of precipitation in the last week, with another .75 to 1.25 inches forecasted for today into tomorrow. 

Last week, we received up to 3 feet of snow and extremely cold temperatures. Then, over the weekend and into this week, we received significant rain up to 8000 ft and very warm temperatures. It was a tropical 44 degrees at 6400 ft at Twin Lakes in the central Bitterroot at 3 am this morning. Today, an atmospheric river is delivering another strong pulse of rain and snow. The snowpack never responds well to such rapid changes. 

We've been concerned about persistent weak layers deep in the snowpack for weeks. Recent avalanches, whumpfing, cracking, poor structure, and easy failures in stability tests have all indicated that the snowpack is primed to fail. Today’s precipitation is likely to tip the balance. 

Today is not the day to take chances. Wet snow avalanche problems are unpredictable and can not be accurately assessed with standard snowpack tests. Very large, full depth avalanches that run from peak to valley are possible. Travel in avalanche terrain or under or through avalanche paths is not recommended. 

If you see evidence of recent avalanche activity, please let us know by submitting an observation. 

Ski and ride safe. 

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