Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

A developing storm will increase the danger and the chance you could trigger an avalanche in new or wind-drifted snow. You will be most at risk where the snow has piled up deepest - near ridgelines, beneath saddles, and in gullies. Choose terrain sheltered from the wind or a lower-angle slope if you find eight or more inches of new snow.

Lawinenprobleme

  • Wind Slabs

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

    Continuous snowfall and gusty southwest winds will form fresh slabs of wind-drifted snow throughout the day. These will become easier to trigger as the day progresses and the snow piles up. New slabs will be the thickest and most dangerous on the downwind sides of ridgelines, beneath saddles, on the sidewalls of gullies, and around prominent terrain features. 

    Look for blowing snow as you gain elevation to identify locations of wind-drifted features. A rippled surface and dune-shaped mounds indicate that the wind has been at work. Cracking beneath your feet or machine is a sign of instability. A shooting crack is a red flag directing you to sheltered terrain or a lower-angle slope.

     

    (2/16/2023)

    Southwest winds load the slopes beneath the north ridge of Mt Penrose.

    Photo: MD

  • Storm Slabs

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

    Today's developing storm may create widespread slabs of new snow by this afternoon. These will become thicker and more dangerous as you gain elevation and as the day progresses. We anticipate that the western and central Flathead Range will receive the most snow in this zone.

    Pay attention to the depth of the new snow as you travel. Areas accumulating eight or more inches of dense snow can produce a dangerous avalanche large enough to bury or injure someone. Like a wind slab, cracking beneath you indicates instability directing you to move elsewhere or choose a lower-angle slope. Avoid dawdling in the runouts of avalanche paths for the next few days as the storm intensifies. 

    Loose Dry: In areas where the surface snow remains loose, expect a Loose Dry avalanche problem to develop on slopes steeper than 35 degrees. Fresh snow is falling on various surfaces, including crusts which may inhibit bonding. Manage your sluff and limit time spent above terrain traps or in long-running gullies.

     

    (12/23/2022)

    Storm slabs were touchy and failed on a layer of extremely low-density snow.

    Photo: Mark Dundas

  • Persistent Slabs

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

    A weak layer of snow exists 1-2 feet beneath the surface in the Flathead Range and southern Glacier Park. Triggering this layer is becoming more difficult but remains possible. A slide in today's fresh snow has the potential to step down to a buried weak layer. The suspect layers are found on all aspects but are most developed and troublesome on shady aspects at mid and upper elevations.

    Dealing with a Persistent Slab problem is tricky. The only way to identify that a slope harbors this problem is to dig down to see if this weak layer exists. The easiest way to manage this issue is through terrain selection. Choose lower-angle planar slopes free of convexities. Steer around areas harboring a thin snowpack, such as wind-scoured or having a rocky peppered appearance, where the weak layer is closer to the surface and more susceptible to the weight of you or your machine. 

    (2/15/2023)

    the new 2/10 crust.

    Photo: Guy

Avalanche Discussion

Copious moisture returns to the Flathead following a prolonged absence. The first of several waves of precipitation entered the area early this morning. The National Weather Service calls for 1.0 - 2.0 inches of SWE and 1-2 feet of snow by Sunday morning. If the storm materializes as forecast, the avalanche danger will rise through the day and overnight. Today, you may find various avalanche problems on all aspects at mid and upper elevations.

After nearly seven weeks of relatively bland and benign avalanche conditions, today is the first of several days of elevated danger lasting into mid-week. Dust off the cobwebs and refresh your avalanche skills if you plan on enjoying the new snow. 

Today, the avalanche danger is similar to what we've experienced recently, with wind slabs at the forefront of our problems. The danger is at MODERATE this morning but may rise to CONSIDERABLE by this afternoon in the Swan and Flathead Range. The Whitefish Range appears to miss the brunt of today's storm, and the danger is forecast to be MODERATE at mid and upper elevations. If today's storm produces heavy snowfall, a widespread storm slab problem will become our primary concern later today. This problem has the potential to affect all aspects and limit the number of safe terrain choices available. 

A substantial storm is forecast to hit our area Sunday night through mid-week. Numerous impacts can be expected from this windy, moisture-laden beast. Stay tuned for details but expect the danger to stay elevated and possibly reach AVALANCHE WARNING status if this weather plays out as advertised. 

Weather trivia: 

  • Yesterday, Missoula recorded the 100th straight day of snow on the ground. This is only the fifth time Missoula has reached this milestone and the earliest date ever. The record is 122 days set during the 1996-97 season. 
  • Kalispell has recorded 87 consecutive days with snow on the ground at KGPI. This streak spans from Nov 23, 2022, to Feb 17, 2023. That makes this the 31st longest streak.

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