Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Small to large avalanches failed on slopes above 6500 feet in the past 48 hours. Shooting cracks, recent avalanches, and audible collapses should point you to lower-angle terrain. Avalanches may be triggered from afar and wrap around terrain features. Give the snowpack time to adjust before riding in steep, consequential terrain. 

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    1 to 3 feet of recent snow rests above soft, weak snow. Natural avalanches and remotely-triggered avalanches were reported above 6500 feet on north-east-southeast facing aspects. Shooting cracks and whumpfing collapses have also occurred recently. This is bullseye information for us to utilize today.

    Whumpfing collapses, shooting cracks, and recent avalanches are all signs of unstable snow. Today, expect to observe these warning signals more commonly on shaded aspects where slabs rest over weak layers. Slabs can be triggered from a distance and propagate surprisingly far distances.

    Keep an eye out for wind-drifted snow in atypical locations. Look for dune-shaped drifts and wind-textured surfaces. Although remote weather stations reported light wind speeds, easterly winds are notorious for drifting snow where they gain momentum as they channel through terrain features.

    (2/12/2024)

    Stomping along a ridgeline produced this and similar shooting cracks in soft slabs of drifted snow on the lee sides. 

    Photo: blase reardon

Avalanche Discussion

We have kept the danger rating elevated in the Swan and Flathead Ranges.  Although we suspect natural avalanche activity to be over, human-triggered avalanches may still be likely. Conditions will be more dangerous near the crests of the Flathead Range and Swan Range where more snow fell. This recent snow landed on weak layers that may be slow to gain strength. 

Recent storm totals vary throughout the forecast region. Below are Snow Water Equivalent (SWE) totals starting February 8th:

Noisy Basin in the Swan Range: 4.8 inches

Stahl in the northern Whitefish Range: 2.5 inches

Whitefish Mountain Resort in the southern Whitefish Range: 1.6 inches

Flattop in Central Glacier National Park: 2 inches *The Flathead Range, especially along the crest in the Middle Fork Corridor, likely received more precipitation.

Southwesterly winds during the storm were generally unimpressive. Blase did find wind-thickened slabs along the crest of the Swan Range on Monday. I’d suspect to find similar conditions along other exposed ridgelines. Winds flipped directions to the east yesterday. Easterly winds can wreak havoc on lower and middle-elevation slopes. Winds commonly channel through valleys, leaving some areas scoured and drifted, with other valleys untouched. Easterly winds are going to ramp up to transportable speeds this evening. If you are out late or planning an evening ride, pay close attention to wind-drifting snow. Slabs will become more sensitive to the weight of a rider.

Recent snow landed on a variety of weak surfaces that vary by aspect. Near-surface facets and surface hoar exist on shaded slopes. We suspect these will be the most sensitive and dangerous slopes at the moment. These are the same slopes that remotely triggered avalanches have failed on.

A crust/facet/crust combination exists on various solar aspects. This structure has been reported in all three ranges. It is more difficult to predict when these aspects will become active. The upper crust allows the weak layer to withstand a larger load before collapsing. This structure can produce very large avalanches IF it receives a substantial loading event.

Keep an eye on the sun and the surface snow IF temperatures become warmer than forecasted. Rollerballs, pinwheels, and point releases out of steep, rocky terrain indicate an impending Wet Loose cycle. Cold air should limit this problem today.

Upcoming event: Flathead Avalanche Friends Fest, February 21-24. We have four days of events on tap for you: Beacons & Brews, Name That Tune/Name That Avalanche, Workshop Night with State of the Snowpack and USGS, Hot Dog Days, and the Ultimate Après with Backcountry Partner Speed Dating and the Big A$$ Raffle. More info at flatheadavalanche.org/event/friendsfest

Regions covered