Avalanche forecast

Swan Range

Flathead Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

As an Arctic air mass moves west, expect shifting winds to form slabs in unusual locations.  Pay attention to the wind direction and look for blowing snow to clue you into today's problem. Slabs formed over the past few days may still be trouble makers. Today's cold conditions require a simple plan to ensure a safe return.

Avalanche problems

  • Wind Slabs

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

    Pay attention to the wind direction, as shifting winds will determine where you find fresh slabs. Winds from the west have formed slabs on the eastern side of the compass for the past few days. Today, an Arctic air mass slowly moves into the Whitefish Range and the Swan Range. Winds look to shift to the north through east and begin forming slabs on atypical aspects. For simplicity's sake, expect to find slabs on all aspects today. Their location may be confusing, but the song remains the same - stay alert for dense, stiff snow resting on softer snow. Cracking is a clue, as is a hollow drum-like sound or feel.  Seek out soft snow in terrain not affected by the wind.

    (12/24/2021)

    A shooting crack is a red flag and signifies that you have encountered instability in the surface snow. These skiers were on a wind-loaded aspect when one deliberately walked above the skin track to determine reactivity in the slab.

    Photo: Jeff Metsky

Avalanche Discussion

An Arctic air mass moved into our area on Christmas Eve but has remained stalled out in the eastern portion of our area, roughly between Essex and Marias Pass. The air temperature in John F. Stevens Canyon has remained below zero in the valley floor and at ridgeline elevations for over 30 hours as of 0500 Sunday.  There are signs that this cold air is slowly moving west and will affect the remainder of the Flathead Range and work its way down the Whitefish Range from north to south as the day progresses. We are unsure if the Swan Range banana belt will see this cold air and north or east winds. 

Arctic events generally produce blustery north through east winds. Not only do the winds compound the bitter cold, but they also transport snow onto atypical aspects. Open slopes, which we usually enjoy riding, can be stripped of snow. Generally, safer windward or westerly aspects near the treeline may develop fresh slabs and become areas of concern. FAC does not have a great handle on where these events are most troublesome.  We know that narrow drainages in the Middle Fork can be sheltered from these winds while the face of Big Mountain and the Swan Range may be ravaged. If you get out today, please let us know what you find to track affected or not from these events.

WIND CHILL WARNING IN EFFECT UNTIL 5 AM MST MONDAY between West Glacier and Marias Pass. Expect dangerously cold wind chills as low as 46 below zero between West Glacier and Marias Pass.  Frostbite may occur on exposed skin in as little as 10 minutes.

Check out the conditions blog for our weekly summary. Each Friday throughout the season, we will post a text and video summarizing the week's snow, weather, and avalanche conditions.

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