Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
Open full map
Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Light snow showers and increasing winds may add weight and form surface slabs above buried weak layers. Collapsing or whumpfing sounds indicate instability, directing you to lower-angle terrain or a different aspect. South and southwest-facing slopes lack these weak layers and are a safer choice. The hazard may rise overnight as the snowfall increases. 

Lawinenprobleme

  • Persistent Slabs

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

    Increasing southwest winds and today's light snowfall will add weight and may form slabs above a layer of surface hoar buried 8-16 inches deep. This layer is most prevalent on shaded aspects at upper and mid-elevations above last weekend's rain line. Rain from the 12/7-12/8 storm destroyed this layer in some locations.

    Hand pits or a quick shovel session will identify if the slope you are on harbors this layer. If in doubt, choose a south or southwest aspect where the sun destroyed this layer on many of these slopes. 

    Shooting cracks or a whumpf indicates you have located this problem and should move to a different slope or lower-angle terrain free of overhead hazards. It remains possible to trigger an avalanche from above, below, or to the side of a steep slope. 

     

    (12/12/2024)

    A snowpit at 7400' on Mt Brown shows 8" of soft snow above the surface hoar layer formed during the strong ridge of high pressure 12/2-12/6. This location lacks a surface slab for a Persistent Slab avalanche to occur.

    Photo: Mark Dundas

Avalanche Discussion

Warm Pacific moisture arrives today and increases overnight. The timing and quantity of precipitation will dictate when the avalanche danger rises. We expect the hazard to creep up by this afternoon, especially in the Whitefish Range, where up to 6 inches may fall by sunset. Most snowfall may only occur during the overnight hours, and our confidence is higher that the danger will increase by Sunday morning, especially in the favored Swan Range. 

Snowfall will add weight to the Whitefish Range, Flathead Range, and Glacier Park buried surface hoar. Avalanches on this layer occurred in the central and northern Whitefish Range during the heavy snow event of 12/7-12/8, but other locations received much less loading. This weekend's storm contains much less water than that event, and we don't anticipate widespread natural avalanche activity. However, the chance for a human-triggered slide may increase as many slopes lack a slab above the weak layer. This storm and warm weather may form the missing ingredient. 

We have bumped the danger up and added a Wind Slab problem at upper elevations to the Swan Range. Southwest winds are increasing and impressively robust at the Aeneas Ridge wind station, which averages 30 mph with gusts of 55. More snow is needed for transport due to the lack of recent snowfall. If this problem develops it will be towards the end of the day. We expect slabs of wind-drifted snow to be more of an issue overnight and tomorrow at mid and upper elevations. 

Did you hear about the app? You can now access our region's forecasts, observations, and weather data directly from the Avy App (IOS; Android). Many features are accessible offline, so you can win debates about the avalanche problems right in the backcountry or submit an obs while driving home. 

Are you looking for avalanche education opportunities? Check out our calendar for upcoming events. Next week, there is an Avalanche Awareness Class at Bias Brewing on Monday, December 16th.

Abgedeckte Regionen