Boletín de aludes

Flathead Range & Glacier NP

Flathead Avalanche Center
Ver en el mapa

Peligro de aludes

Mon
Alta montaña
1 · Débil
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
Desactualizado: este boletín caducó last year. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

A strong overnight refreeze will delay the onset of today's wet snow problems. As the near-surface crust thaws, you could trigger a wet snow avalanche in areas where you sink into mushy snow. Sustained sunshine may initiate falling cornices or glide avalanches. Limit your time spent on sun-baked slopes, especially this afternoon, and move to a shadier aspect if you find an unsupportable surface. 

Problemas de aludes

  • Wet Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    1.5–3

    Last week's rain and warm temperatures allowed meltwater to move through the snowpack to buried weak layers, resulting in large wet slab avalanches. Recent cooling temperatures and dry conditions have slowed the movement of this free water.  This morning's surface crust will limit production of new meltwater from today's strong sunshine. However, there remains plenty of wet snow beneath the newly formed crust, and the potential for a large avalanche remains.

    Although unlikely, riders can trigger a large wet snow avalanche after the surface crust breaks down or in locations where it does not exist.  If you find yourself sinking into a mushy surface, move to a shadier aspect or a lower-angle slope to minimize your chances of initiating a slide. Natural avalanches are not expected, but you can limit your exposure by reducing the time spent on or under steep, open slopes later in the day. This is especially true of those harboring large cornices, where a falling block could trigger an avalanche deeper in the pack.

    Saturday's short-lived sunshine initiated rollerballs in recent storm snow. With more sustained solar expected today, anticipate this problem moving up in elevation. Associated wet loose slides should be harmless unless they knock you off your feet and push you into an area where you shouldn't be, such as tree stands, cliffs, or gullies.

     

    (3/28/2025)

    Wet snow on Red Meadow Peak failed as sluffs and slabs.  Triggering slabs of wet snow is possible where you do not find a supportable surface crust. 

    Photo: Flathead Avalanche Center

  • Glide Cracks

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    2–3

    Area SNOTEL stations report modest SWE loss over the past few days, indicating water is moving through the snowpack. Where the water reaches the snow and ground interface, weakening occurs. If a glide crack is present, a large destructive avalanche involving the seasonal snow cover could occur. Two glide avalanches occurred in the Swan Front on Saturday, the first of this type of avalanche in many weeks.  

    Today's sun and warming temperatures keep this as a potential problem. The surface crust at mid-elevations is thin and weak and will break down quickly, possibly allowing meltwater to continue migrating toward the ground. 

    Predicting whether and when these unusual avalanches will occur is difficult at best. The best way to mitigate this problem is to avoid traveling beneath slopes that harbor glide cracks. Although found on all aspects and elevations, these cracks appear to be concentrated on sunny slopes at mid-elevations.  

    (3/29/2025) Brown's Bowl, Northern Swan. Two glide avalanches likely ran 3/29 (red) though this terrain was obscured on 3/28. An older glide avalanche (yellow) ran 3/26. Photo: Chris Gotschalk

Avalanche Discussion

Temperatures dropped below freezing at all elevations overnight for the first time since last Sunday. As of this morning, upper elevations have now been below freezing for roughly 48-60 hours. More importantly, these temperatures dropped from just below freezing to 20-25°F, forming a much stronger surface crust. Mid-elevations dropped below freezing after sunset, and the surface crust will be thinner and softer at that elevation. Recent snowfall is insulating the surface and slowing the crust formation. 

Cooler temperatures, along with the crust, will limit the onset of today's wet snow hazards. However, the late-March sun is intense, and the surface can rapidly heat up, undergoing significant changes. Develop a plan that allows you to avoid steep, sunny slopes on your afternoon exit.

With another day of sunshine and warm temperatures, we will keep glide avalanches on the problem list. Two glide avalanches failed on the Swan Front on Saturday. Interestingly, these are the first glide failures observed in many weeks.  The recent intense rain from earlier in the week did not cause failure but likely added substantial meltwater to the snowpack.

Several inches of dense, moist snow fell on Friday. At upper elevations, you may encounter thin slabs of wind-blown snow or of fallen snow. These should be harmless and easy to avoid. 

Eastern Oregon University is conducting a survey to better understand avalanche safety preparedness among motorized backcountry users. The survey will help us learn more about who is purchasing and practicing with avalanche rescue gear (beacon, probe, shovel) and participating in avalanche education—and why some riders are not. The survey is confidential and anonymous. Your feedback is invaluable in improving avalanche education and awareness. Please take a moment to share your experience and help us make a difference:

https://eoustmhs.qualtrics.com/jfe/form/SV_3L8QKAuZzcxJBLo

 

Regiones cubiertas